*
* The value represented by a NumericVar is determined by the sign, weight,
* ndigits, and digits[] array.
+ *
* Note: the first digit of a NumericVar's value is assumed to be multiplied
* by NBASE ** weight. Another way to say it is that there are weight+1
* digits before the decimal point. It is possible to have weight < 0.
* Note that rscale is not stored in variables --- it's figured on-the-fly
* from the dscales of the inputs.
*
+ * While we consistently use "weight" to refer to the base-NBASE weight of
+ * a numeric value, it is convenient in some scale-related calculations to
+ * make use of the base-10 weight (ie, the approximate log10 of the value).
+ * To avoid confusion, such a decimal-units weight is called a "dweight".
+ *
* NB: All the variable-level functions are written in a style that makes it
* possible to give one and the same variable as argument and destination.
* This is feasible because the digit buffer is separate from the variable.
static NumericVar const_zero_point_nine =
{1, -1, NUMERIC_POS, 1, NULL, const_zero_point_nine_data};
-#if DEC_DIGITS == 4
-static NumericDigit const_zero_point_01_data[1] = {100};
-static NumericVar const_zero_point_01 =
-{1, -1, NUMERIC_POS, 2, NULL, const_zero_point_01_data};
-#elif DEC_DIGITS == 2
-static NumericDigit const_zero_point_01_data[1] = {1};
-static NumericVar const_zero_point_01 =
-{1, -1, NUMERIC_POS, 2, NULL, const_zero_point_01_data};
-#elif DEC_DIGITS == 1
-static NumericDigit const_zero_point_01_data[1] = {1};
-static NumericVar const_zero_point_01 =
-{1, -2, NUMERIC_POS, 2, NULL, const_zero_point_01_data};
-#endif
-
#if DEC_DIGITS == 4
static NumericDigit const_one_point_one_data[2] = {1, 1000};
#elif DEC_DIGITS == 2
static void sqrt_var(NumericVar *arg, NumericVar *result, int rscale);
static void exp_var(NumericVar *arg, NumericVar *result, int rscale);
-static void exp_var_internal(NumericVar *arg, NumericVar *result, int rscale);
+static int estimate_ln_dweight(NumericVar *var);
static void ln_var(NumericVar *arg, NumericVar *result, int rscale);
static void log_var(NumericVar *base, NumericVar *num, NumericVar *result);
static void power_var(NumericVar *base, NumericVar *exp, NumericVar *result);
Numeric res;
NumericVar arg;
NumericVar result;
- int dec_digits;
+ int ln_dweight;
int rscale;
/*
init_var_from_num(num, &arg);
init_var(&result);
- /* Approx decimal digits before decimal point */
- dec_digits = (arg.weight + 1) * DEC_DIGITS;
-
- if (dec_digits > 1)
- rscale = NUMERIC_MIN_SIG_DIGITS - (int) log10(dec_digits - 1);
- else if (dec_digits < 1)
- rscale = NUMERIC_MIN_SIG_DIGITS - (int) log10(1 - dec_digits);
- else
- rscale = NUMERIC_MIN_SIG_DIGITS;
+ /* Estimated dweight of logarithm */
+ ln_dweight = estimate_ln_dweight(&arg);
+ rscale = NUMERIC_MIN_SIG_DIGITS - ln_dweight;
rscale = Max(rscale, arg.dscale);
rscale = Max(rscale, NUMERIC_MIN_DISPLAY_SCALE);
rscale = Min(rscale, NUMERIC_MAX_DISPLAY_SCALE);
int carry;
int maxdig;
int newdig;
+ int var1ndigits;
+ int var2ndigits;
+ NumericDigit *var1digits;
+ NumericDigit *var2digits;
NumericDigit *res_digits;
int i,
- ri,
i1,
i2;
+ /*
+ * Arrange for var1 to be the shorter of the two numbers. This improves
+ * performance because the inner multiplication loop is much simpler than
+ * the outer loop, so it's better to have a smaller number of iterations
+ * of the outer loop. This also reduces the number of times that the
+ * accumulator array needs to be normalized.
+ */
+ if (var1->ndigits > var2->ndigits)
+ {
+ NumericVar *tmp = var1;
+
+ var1 = var2;
+ var2 = tmp;
+ }
+
/* copy these values into local vars for speed in inner loop */
- int var1ndigits = var1->ndigits;
- int var2ndigits = var2->ndigits;
- NumericDigit *var1digits = var1->digits;
- NumericDigit *var2digits = var2->digits;
+ var1ndigits = var1->ndigits;
+ var2ndigits = var2->ndigits;
+ var1digits = var1->digits;
+ var2digits = var2->digits;
if (var1ndigits == 0 || var2ndigits == 0)
{
res_weight = var1->weight + var2->weight + 2;
/*
- * Determine number of result digits to compute. If the exact result
+ * Determine the number of result digits to compute. If the exact result
* would have more than rscale fractional digits, truncate the computation
- * with MUL_GUARD_DIGITS guard digits. We do that by pretending that one
- * or both inputs have fewer digits than they really do.
+ * with MUL_GUARD_DIGITS guard digits, i.e., ignore input digits that
+ * would only contribute to the right of that. (This will give the exact
+ * rounded-to-rscale answer unless carries out of the ignored positions
+ * would have propagated through more than MUL_GUARD_DIGITS digits.)
+ *
+ * Note: an exact computation could not produce more than var1ndigits +
+ * var2ndigits digits, but we allocate one extra output digit in case
+ * rscale-driven rounding produces a carry out of the highest exact digit.
*/
res_ndigits = var1ndigits + var2ndigits + 1;
- maxdigits = res_weight + 1 + (rscale * DEC_DIGITS) + MUL_GUARD_DIGITS;
- if (res_ndigits > maxdigits)
+ maxdigits = res_weight + 1 + (rscale + DEC_DIGITS - 1) / DEC_DIGITS +
+ MUL_GUARD_DIGITS;
+ res_ndigits = Min(res_ndigits, maxdigits);
+
+ if (res_ndigits < 3)
{
- if (maxdigits < 3)
- {
- /* no useful precision at all in the result... */
- zero_var(result);
- result->dscale = rscale;
- return;
- }
- /* force maxdigits odd so that input ndigits can be equal */
- if ((maxdigits & 1) == 0)
- maxdigits++;
- if (var1ndigits > var2ndigits)
- {
- var1ndigits -= res_ndigits - maxdigits;
- if (var1ndigits < var2ndigits)
- var1ndigits = var2ndigits = (var1ndigits + var2ndigits) / 2;
- }
- else
- {
- var2ndigits -= res_ndigits - maxdigits;
- if (var2ndigits < var1ndigits)
- var1ndigits = var2ndigits = (var1ndigits + var2ndigits) / 2;
- }
- res_ndigits = maxdigits;
- Assert(res_ndigits == var1ndigits + var2ndigits + 1);
+ /* All input digits will be ignored; so result is zero */
+ zero_var(result);
+ result->dscale = rscale;
+ return;
}
/*
dig = (int *) palloc0(res_ndigits * sizeof(int));
maxdig = 0;
- ri = res_ndigits - 1;
- for (i1 = var1ndigits - 1; i1 >= 0; ri--, i1--)
+ /*
+ * The least significant digits of var1 should be ignored if they don't
+ * contribute directly to the first res_ndigits digits of the result that
+ * we are computing.
+ *
+ * Digit i1 of var1 and digit i2 of var2 are multiplied and added to digit
+ * i1+i2+2 of the accumulator array, so we need only consider digits of
+ * var1 for which i1 <= res_ndigits - 3.
+ */
+ for (i1 = Min(var1ndigits - 1, res_ndigits - 3); i1 >= 0; i1--)
{
int var1digit = var1digits[i1];
maxdig = 1 + var1digit;
}
- /* Add appropriate multiple of var2 into the accumulator */
- i = ri;
- for (i2 = var2ndigits - 1; i2 >= 0; i2--)
+ /*
+ * Add the appropriate multiple of var2 into the accumulator.
+ *
+ * As above, digits of var2 can be ignored if they don't contribute,
+ * so we only include digits for which i1+i2+2 <= res_ndigits - 1.
+ */
+ for (i2 = Min(var2ndigits - 1, res_ndigits - i1 - 3), i = i1 + i2 + 2;
+ i2 >= 0; i2--)
dig[i--] += var1digit * var2digits[i2];
}
/*
* exp_var() -
*
- * Raise e to the power of x
+ * Raise e to the power of x, computed to rscale fractional digits
*/
static void
exp_var(NumericVar *arg, NumericVar *result, int rscale)
{
NumericVar x;
- int xintval;
- bool xneg = FALSE;
+ NumericVar elem;
+ NumericVar ni;
+ double val;
+ int dweight;
+ int ndiv2;
+ int sig_digits;
int local_rscale;
- /*----------
- * We separate the integral and fraction parts of x, then compute
- * e^x = e^xint * e^xfrac
- * where e = exp(1) and e^xfrac = exp(xfrac) are computed by
- * exp_var_internal; the limited range of inputs allows that routine
- * to do a good job with a simple Taylor series. Raising e^xint is
- * done by repeated multiplications in power_var_int.
- *----------
- */
init_var(&x);
+ init_var(&elem);
+ init_var(&ni);
set_var_from_var(arg, &x);
- if (x.sign == NUMERIC_NEG)
- {
- xneg = TRUE;
- x.sign = NUMERIC_POS;
- }
-
- /* Extract the integer part, remove it from x */
- xintval = 0;
- while (x.weight >= 0)
- {
- xintval *= NBASE;
- if (x.ndigits > 0)
- {
- xintval += x.digits[0];
- x.digits++;
- x.ndigits--;
- }
- x.weight--;
- /* Guard against overflow */
- if (xintval >= NUMERIC_MAX_RESULT_SCALE * 3)
- ereport(ERROR,
- (errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
- errmsg("argument for function \"exp\" too big")));
- }
+ /*
+ * Estimate the dweight of the result using floating point arithmetic, so
+ * that we can choose an appropriate local rscale for the calculation.
+ */
+ val = numericvar_to_double_no_overflow(&x);
- /* Select an appropriate scale for internal calculation */
- local_rscale = rscale + MUL_GUARD_DIGITS * 2;
+ /* Guard against overflow */
+ if (Abs(val) >= NUMERIC_MAX_RESULT_SCALE * 3)
+ ereport(ERROR,
+ (errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
+ errmsg("value overflows numeric format")));
- /* Compute e^xfrac */
- exp_var_internal(&x, result, local_rscale);
+ /* decimal weight = log10(e^x) = x * log10(e) */
+ dweight = (int) (val * 0.434294481903252);
- /* If there's an integer part, multiply by e^xint */
- if (xintval > 0)
+ /*
+ * Reduce x to the range -0.01 <= x <= 0.01 (approximately) by dividing by
+ * 2^n, to improve the convergence rate of the Taylor series.
+ */
+ if (Abs(val) > 0.01)
{
- NumericVar e;
+ NumericVar tmp;
- init_var(&e);
- exp_var_internal(&const_one, &e, local_rscale);
- power_var_int(&e, xintval, &e, local_rscale);
- mul_var(&e, result, result, local_rscale);
- free_var(&e);
- }
+ init_var(&tmp);
+ set_var_from_var(&const_two, &tmp);
- /* Compensate for input sign, and round to requested rscale */
- if (xneg)
- div_var_fast(&const_one, result, result, rscale, true);
- else
- round_var(result, rscale);
-
- free_var(&x);
-}
-
-
-/*
- * exp_var_internal() -
- *
- * Raise e to the power of x, where 0 <= x <= 1
- *
- * NB: the result should be good to at least rscale digits, but it has
- * *not* been rounded off; the caller must do that if wanted.
- */
-static void
-exp_var_internal(NumericVar *arg, NumericVar *result, int rscale)
-{
- NumericVar x;
- NumericVar xpow;
- NumericVar ifac;
- NumericVar elem;
- NumericVar ni;
- int ndiv2 = 0;
- int local_rscale;
+ ndiv2 = 1;
+ val /= 2;
- init_var(&x);
- init_var(&xpow);
- init_var(&ifac);
- init_var(&elem);
- init_var(&ni);
+ while (Abs(val) > 0.01)
+ {
+ ndiv2++;
+ val /= 2;
+ add_var(&tmp, &tmp, &tmp);
+ }
- set_var_from_var(arg, &x);
+ local_rscale = x.dscale + ndiv2;
+ div_var_fast(&x, &tmp, &x, local_rscale, true);
- Assert(x.sign == NUMERIC_POS);
+ free_var(&tmp);
+ }
+ else
+ ndiv2 = 0;
- local_rscale = rscale + 8;
+ /*
+ * Set the scale for the Taylor series expansion. The final result has
+ * (dweight + rscale + 1) significant digits. In addition, we have to
+ * raise the Taylor series result to the power 2^ndiv2, which introduces
+ * an error of up to around log10(2^ndiv2) digits, so work with this many
+ * extra digits of precision (plus a few more for good measure).
+ */
+ sig_digits = 1 + dweight + rscale + (int) (ndiv2 * 0.301029995663981);
+ sig_digits = Max(sig_digits, 0) + 8;
- /* Reduce input into range 0 <= x <= 0.01 */
- while (cmp_var(&x, &const_zero_point_01) > 0)
- {
- ndiv2++;
- local_rscale++;
- mul_var(&x, &const_zero_point_five, &x, x.dscale + 1);
- }
+ local_rscale = sig_digits - 1;
/*
* Use the Taylor series
* We run the series until the terms fall below the local_rscale limit.
*/
add_var(&const_one, &x, result);
- set_var_from_var(&x, &xpow);
- set_var_from_var(&const_one, &ifac);
- set_var_from_var(&const_one, &ni);
- for (;;)
- {
- add_var(&ni, &const_one, &ni);
- mul_var(&xpow, &x, &xpow, local_rscale);
- mul_var(&ifac, &ni, &ifac, 0);
- div_var_fast(&xpow, &ifac, &elem, local_rscale, true);
-
- if (elem.ndigits == 0)
- break;
+ mul_var(&x, &x, &elem, local_rscale);
+ set_var_from_var(&const_two, &ni);
+ div_var_fast(&elem, &ni, &elem, local_rscale, true);
+ while (elem.ndigits != 0)
+ {
add_var(result, &elem, result);
+
+ mul_var(&elem, &x, &elem, local_rscale);
+ add_var(&ni, &const_one, &ni);
+ div_var_fast(&elem, &ni, &elem, local_rscale, true);
}
- /* Compensate for argument range reduction */
+ /*
+ * Compensate for the argument range reduction. Since the weight of the
+ * result doubles with each multiplication, we can reduce the local rscale
+ * as we proceed.
+ */
while (ndiv2-- > 0)
+ {
+ local_rscale = sig_digits - result->weight * 2 * DEC_DIGITS;
+ local_rscale = Max(local_rscale, NUMERIC_MIN_DISPLAY_SCALE);
mul_var(result, result, result, local_rscale);
+ }
+
+ /* Round to requested rscale */
+ round_var(result, rscale);
free_var(&x);
- free_var(&xpow);
- free_var(&ifac);
free_var(&elem);
free_var(&ni);
}
+/*
+ * Estimate the dweight of the most significant decimal digit of the natural
+ * logarithm of a number.
+ *
+ * Essentially, we're approximating log10(abs(ln(var))). This is used to
+ * determine the appropriate rscale when computing natural logarithms.
+ */
+static int
+estimate_ln_dweight(NumericVar *var)
+{
+ int ln_dweight;
+
+ if (cmp_var(var, &const_zero_point_nine) >= 0 &&
+ cmp_var(var, &const_one_point_one) <= 0)
+ {
+ /*
+ * 0.9 <= var <= 1.1
+ *
+ * ln(var) has a negative weight (possibly very large). To get a
+ * reasonably accurate result, estimate it using ln(1+x) ~= x.
+ */
+ NumericVar x;
+
+ init_var(&x);
+ sub_var(var, &const_one, &x);
+
+ if (x.ndigits > 0)
+ {
+ /* Use weight of most significant decimal digit of x */
+ ln_dweight = x.weight * DEC_DIGITS + (int) log10(x.digits[0]);
+ }
+ else
+ {
+ /* x = 0. Since ln(1) = 0 exactly, we don't need extra digits */
+ ln_dweight = 0;
+ }
+
+ free_var(&x);
+ }
+ else
+ {
+ /*
+ * Estimate the logarithm using the first couple of digits from the
+ * input number. This will give an accurate result whenever the input
+ * is not too close to 1.
+ */
+ if (var->ndigits > 0)
+ {
+ int digits;
+ int dweight;
+ double ln_var;
+
+ digits = var->digits[0];
+ dweight = var->weight * DEC_DIGITS;
+
+ if (var->ndigits > 1)
+ {
+ digits = digits * NBASE + var->digits[1];
+ dweight -= DEC_DIGITS;
+ }
+
+ /*----------
+ * We have var ~= digits * 10^dweight
+ * so ln(var) ~= ln(digits) + dweight * ln(10)
+ *----------
+ */
+ ln_var = log((double) digits) + dweight * 2.302585092994046;
+ ln_dweight = (int) log10(Abs(ln_var));
+ }
+ else
+ {
+ /* Caller should fail on ln(0), but for the moment return zero */
+ ln_dweight = 0;
+ }
+ }
+
+ return ln_dweight;
+}
+
+
/*
* ln_var() -
*
(errcode(ERRCODE_INVALID_ARGUMENT_FOR_LOG),
errmsg("cannot take logarithm of a negative number")));
- local_rscale = rscale + 8;
-
init_var(&x);
init_var(&xx);
init_var(&ni);
set_var_from_var(arg, &x);
set_var_from_var(&const_two, &fact);
- /* Reduce input into range 0.9 < x < 1.1 */
+ /*
+ * Reduce input into range 0.9 < x < 1.1 with repeated sqrt() operations.
+ *
+ * The final logarithm will have up to around rscale+6 significant digits.
+ * Each sqrt() will roughly halve the weight of x, so adjust the local
+ * rscale as we work so that we keep this many significant digits at each
+ * step (plus a few more for good measure).
+ */
while (cmp_var(&x, &const_zero_point_nine) <= 0)
{
- local_rscale++;
+ local_rscale = rscale - x.weight * DEC_DIGITS / 2 + 8;
+ local_rscale = Max(local_rscale, NUMERIC_MIN_DISPLAY_SCALE);
sqrt_var(&x, &x, local_rscale);
mul_var(&fact, &const_two, &fact, 0);
}
while (cmp_var(&x, &const_one_point_one) >= 0)
{
- local_rscale++;
+ local_rscale = rscale - x.weight * DEC_DIGITS / 2 + 8;
+ local_rscale = Max(local_rscale, NUMERIC_MIN_DISPLAY_SCALE);
sqrt_var(&x, &x, local_rscale);
mul_var(&fact, &const_two, &fact, 0);
}
* The convergence of this is not as fast as one would like, but is
* tolerable given that z is small.
*/
+ local_rscale = rscale + 8;
+
sub_var(&x, &const_one, result);
add_var(&x, &const_one, &elem);
div_var_fast(result, &elem, result, local_rscale, true);
{
NumericVar ln_base;
NumericVar ln_num;
- int dec_digits;
+ int ln_base_dweight;
+ int ln_num_dweight;
+ int result_dweight;
int rscale;
- int local_rscale;
+ int ln_base_rscale;
+ int ln_num_rscale;
init_var(&ln_base);
init_var(&ln_num);
- /* Set scale for ln() calculations --- compare numeric_ln() */
-
- /* Approx decimal digits before decimal point */
- dec_digits = (num->weight + 1) * DEC_DIGITS;
-
- if (dec_digits > 1)
- rscale = NUMERIC_MIN_SIG_DIGITS - (int) log10(dec_digits - 1);
- else if (dec_digits < 1)
- rscale = NUMERIC_MIN_SIG_DIGITS - (int) log10(1 - dec_digits);
- else
- rscale = NUMERIC_MIN_SIG_DIGITS;
+ /* Estimated dweights of ln(base), ln(num) and the final result */
+ ln_base_dweight = estimate_ln_dweight(base);
+ ln_num_dweight = estimate_ln_dweight(num);
+ result_dweight = ln_num_dweight - ln_base_dweight;
+ /*
+ * Select the scale of the result so that it will have at least
+ * NUMERIC_MIN_SIG_DIGITS significant digits and is not less than either
+ * input's display scale.
+ */
+ rscale = NUMERIC_MIN_SIG_DIGITS - result_dweight;
rscale = Max(rscale, base->dscale);
rscale = Max(rscale, num->dscale);
rscale = Max(rscale, NUMERIC_MIN_DISPLAY_SCALE);
rscale = Min(rscale, NUMERIC_MAX_DISPLAY_SCALE);
- local_rscale = rscale + 8;
-
- /* Form natural logarithms */
- ln_var(base, &ln_base, local_rscale);
- ln_var(num, &ln_num, local_rscale);
+ /*
+ * Set the scales for ln(base) and ln(num) so that they each have more
+ * significant digits than the final result.
+ */
+ ln_base_rscale = rscale + result_dweight - ln_base_dweight + 8;
+ ln_base_rscale = Max(ln_base_rscale, NUMERIC_MIN_DISPLAY_SCALE);
- ln_base.dscale = rscale;
- ln_num.dscale = rscale;
+ ln_num_rscale = rscale + result_dweight - ln_num_dweight + 8;
+ ln_num_rscale = Max(ln_num_rscale, NUMERIC_MIN_DISPLAY_SCALE);
- /* Select scale for division result */
- rscale = select_div_scale(&ln_num, &ln_base);
+ /* Form natural logarithms */
+ ln_var(base, &ln_base, ln_base_rscale);
+ ln_var(num, &ln_num, ln_num_rscale);
+ /* Divide and round to the required scale */
div_var_fast(&ln_num, &ln_base, result, rscale, true);
free_var(&ln_num);
{
NumericVar ln_base;
NumericVar ln_num;
- int dec_digits;
+ int ln_dweight;
int rscale;
int local_rscale;
double val;
}
/*
- * This avoids log(0) for cases of 0 raised to a non-integer. 0 ^ 0
+ * This avoids log(0) for cases of 0 raised to a non-integer. 0 ^ 0 is
* handled by power_var_int().
*/
if (cmp_var(base, &const_zero) == 0)
init_var(&ln_base);
init_var(&ln_num);
- /* Set scale for ln() calculation --- need extra accuracy here */
-
- /* Approx decimal digits before decimal point */
- dec_digits = (base->weight + 1) * DEC_DIGITS;
-
- if (dec_digits > 1)
- rscale = NUMERIC_MIN_SIG_DIGITS * 2 - (int) log10(dec_digits - 1);
- else if (dec_digits < 1)
- rscale = NUMERIC_MIN_SIG_DIGITS * 2 - (int) log10(1 - dec_digits);
- else
- rscale = NUMERIC_MIN_SIG_DIGITS * 2;
-
- rscale = Max(rscale, base->dscale * 2);
- rscale = Max(rscale, exp->dscale * 2);
- rscale = Max(rscale, NUMERIC_MIN_DISPLAY_SCALE * 2);
- rscale = Min(rscale, NUMERIC_MAX_DISPLAY_SCALE * 2);
+ /*----------
+ * Decide on the scale for the ln() calculation. For this we need an
+ * estimate of the weight of the result, which we obtain by doing an
+ * initial low-precision calculation of exp * ln(base).
+ *
+ * We want result = e ^ (exp * ln(base))
+ * so result dweight = log10(result) = exp * ln(base) * log10(e)
+ *----------
+ */
+ ln_dweight = estimate_ln_dweight(base);
- local_rscale = rscale + 8;
+ local_rscale = 8 - ln_dweight;
+ local_rscale = Max(local_rscale, NUMERIC_MIN_DISPLAY_SCALE);
+ local_rscale = Min(local_rscale, NUMERIC_MAX_DISPLAY_SCALE);
ln_var(base, &ln_base, local_rscale);
mul_var(&ln_base, exp, &ln_num, local_rscale);
- /* Set scale for exp() -- compare numeric_exp() */
-
- /* convert input to float8, ignoring overflow */
val = numericvar_to_double_no_overflow(&ln_num);
- /*
- * log10(result) = num * log10(e), so this is approximately the weight:
- */
- val *= 0.434294481903252;
+ val *= 0.434294481903252; /* approximate decimal result weight */
/* limit to something that won't cause integer overflow */
val = Max(val, -NUMERIC_MAX_RESULT_SCALE);
val = Min(val, NUMERIC_MAX_RESULT_SCALE);
+ /* choose the result scale */
rscale = NUMERIC_MIN_SIG_DIGITS - (int) val;
rscale = Max(rscale, base->dscale);
rscale = Max(rscale, exp->dscale);
rscale = Max(rscale, NUMERIC_MIN_DISPLAY_SCALE);
rscale = Min(rscale, NUMERIC_MAX_DISPLAY_SCALE);
+ /* set the scale for the real exp * ln(base) calculation */
+ local_rscale = rscale + (int) val - ln_dweight + 8;
+ local_rscale = Max(local_rscale, NUMERIC_MIN_DISPLAY_SCALE);
+
+ /* and do the real calculation */
+
+ ln_var(base, &ln_base, local_rscale);
+
+ mul_var(&ln_base, exp, &ln_num, local_rscale);
+
exp_var(&ln_num, result, rscale);
free_var(&ln_num);
static void
power_var_int(NumericVar *base, int exp, NumericVar *result, int rscale)
{
+ double f;
+ int p;
+ int i;
+ int sig_digits;
unsigned int mask;
bool neg;
NumericVar base_prod;
break;
}
+ /* Handle the special case where the base is zero */
+ if (base->ndigits == 0)
+ {
+ if (exp < 0)
+ ereport(ERROR,
+ (errcode(ERRCODE_DIVISION_BY_ZERO),
+ errmsg("division by zero")));
+ zero_var(result);
+ result->dscale = rscale;
+ return;
+ }
+
/*
* The general case repeatedly multiplies base according to the bit
- * pattern of exp. We do the multiplications with some extra precision.
+ * pattern of exp.
+ *
+ * First we need to estimate the weight of the result so that we know how
+ * many significant digits are needed.
+ */
+ f = base->digits[0];
+ p = base->weight * DEC_DIGITS;
+
+ for (i = 1; i < base->ndigits && i * DEC_DIGITS < 16; i++)
+ {
+ f = f * NBASE + base->digits[i];
+ p -= DEC_DIGITS;
+ }
+
+ /*----------
+ * We have base ~= f * 10^p
+ * so log10(result) = log10(base^exp) ~= exp * (log10(f) + p)
+ *----------
+ */
+ f = exp * (log10(f) + p);
+
+ /*
+ * Apply crude overflow/underflow tests so we can exit early if the result
+ * certainly will overflow/underflow.
+ */
+ if (f > 3 * SHRT_MAX * DEC_DIGITS)
+ ereport(ERROR,
+ (errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
+ errmsg("value overflows numeric format")));
+ if (f + 1 < -rscale || f + 1 < -NUMERIC_MAX_DISPLAY_SCALE)
+ {
+ zero_var(result);
+ result->dscale = rscale;
+ return;
+ }
+
+ /*
+ * Approximate number of significant digits in the result. Note that the
+ * underflow test above means that this is necessarily >= 0.
+ */
+ sig_digits = 1 + rscale + (int) f;
+
+ /*
+ * The multiplications to produce the result may introduce an error of up
+ * to around log10(abs(exp)) digits, so work with this many extra digits
+ * of precision (plus a few more for good measure).
+ */
+ sig_digits += (int) log(Abs(exp)) + 8;
+
+ /*
+ * Now we can proceed with the multiplications.
*/
neg = (exp < 0);
mask = Abs(exp);
- local_rscale = rscale + MUL_GUARD_DIGITS * 2;
-
init_var(&base_prod);
set_var_from_var(base, &base_prod);
while ((mask >>= 1) > 0)
{
+ /*
+ * Do the multiplications using rscales large enough to hold the
+ * results to the required number of significant digits, but don't
+ * waste time by exceeding the scales of the numbers themselves.
+ */
+ local_rscale = sig_digits - 2 * base_prod.weight * DEC_DIGITS;
+ local_rscale = Min(local_rscale, 2 * base_prod.dscale);
+ local_rscale = Max(local_rscale, NUMERIC_MIN_DISPLAY_SCALE);
+
mul_var(&base_prod, &base_prod, &base_prod, local_rscale);
+
if (mask & 1)
+ {
+ local_rscale = sig_digits -
+ (base_prod.weight + result->weight) * DEC_DIGITS;
+ local_rscale = Min(local_rscale,
+ base_prod.dscale + result->dscale);
+ local_rscale = Max(local_rscale, NUMERIC_MIN_DISPLAY_SCALE);
+
mul_var(&base_prod, result, result, local_rscale);
+ }
/*
* When abs(base) > 1, the number of digits to the left of the decimal
-----+--------+----------
(0 rows)
+--
+-- Test code path for raising to integer powers
+--
+-- base less than 1
+--
+-- bc(1) results computed with a scale of 500 and truncated using the script
+-- below, and then rounded by hand to match the precision of POW():
+--
+-- for p in {-20..20}
+-- do
+-- b="0.084738"
+-- r=$(bc -ql <<< "scale=500 ; $b^$p" | head -n 1)
+-- echo "($b, $p, $r),"
+-- done
+WITH t(b, p, bc_result) AS (VALUES
+(0.084738, -20, 2744326694304960114888.7859130502035257),
+(0.084738, -19, 232548755422013710215.4459407000481464),
+(0.084738, -18, 19705716436950597776.2364581230406798),
+(0.084738, -17, 1669822999434319754.3627249884302211),
+(0.084738, -16, 141497461326065387.3451885900696001),
+(0.084738, -15, 11990211877848128.7928565907453178),
+(0.084738, -14, 1016026574105094.7376490817865767),
+(0.084738, -13, 86096059836517.5178789078924309),
+(0.084738, -12, 7295607918426.8214300228969888),
+(0.084738, -11, 618215223791.6519943372802450),
+(0.084738, -10, 52386321633.6570066961524534),
+(0.084738, -9, 4439112122.5928274334185666),
+(0.084738, -8, 376161483.0442710110530225),
+(0.084738, -7, 31875171.7502054369346110),
+(0.084738, -6, 2701038.3037689083149651),
+(0.084738, -5, 228880.5837847697527935),
+(0.084738, -4, 19394.8829087538193122),
+(0.084738, -3, 1643.4835879219811409),
+(0.084738, -2, 139.2655122733328379),
+(0.084738, -1, 11.8010809790176780),
+(0.084738, 0, 1),
+(0.084738, 1, .084738),
+(0.084738, 2, .007180528644),
+(0.084738, 3, .0006084636362353),
+(0.084738, 4, .0000515599916073),
+(0.084738, 5, .0000043690905688),
+(0.084738, 6, .0000003702279966),
+(0.084738, 7, .0000000313723800),
+(0.084738, 8, .0000000026584327),
+(0.084738, 9, .0000000002252703),
+(0.084738, 10, .0000000000190890),
+(0.084738, 11, .0000000000016176),
+(0.084738, 12, .0000000000001371),
+(0.084738, 13, .0000000000000116),
+(0.084738, 14, .0000000000000010),
+(0.084738, 15, .0000000000000001),
+(0.084738, 16, .0000000000000000),
+(0.084738, 17, .0000000000000000),
+(0.084738, 18, .0000000000000000),
+(0.084738, 19, .0000000000000000),
+(0.084738, 20, .0000000000000000))
+SELECT b, p, bc_result, b^p AS power, b^p - bc_result AS diff FROM t;
+ b | p | bc_result | power | diff
+----------+-----+-----------------------------------------+-----------------------------------------+--------------------
+ 0.084738 | -20 | 2744326694304960114888.7859130502035257 | 2744326694304960114888.7859130502035257 | 0.0000000000000000
+ 0.084738 | -19 | 232548755422013710215.4459407000481464 | 232548755422013710215.4459407000481464 | 0.0000000000000000
+ 0.084738 | -18 | 19705716436950597776.2364581230406798 | 19705716436950597776.2364581230406798 | 0.0000000000000000
+ 0.084738 | -17 | 1669822999434319754.3627249884302211 | 1669822999434319754.3627249884302211 | 0.0000000000000000
+ 0.084738 | -16 | 141497461326065387.3451885900696001 | 141497461326065387.3451885900696001 | 0.0000000000000000
+ 0.084738 | -15 | 11990211877848128.7928565907453178 | 11990211877848128.7928565907453178 | 0.0000000000000000
+ 0.084738 | -14 | 1016026574105094.7376490817865767 | 1016026574105094.7376490817865767 | 0.0000000000000000
+ 0.084738 | -13 | 86096059836517.5178789078924309 | 86096059836517.5178789078924309 | 0.0000000000000000
+ 0.084738 | -12 | 7295607918426.8214300228969888 | 7295607918426.8214300228969888 | 0.0000000000000000
+ 0.084738 | -11 | 618215223791.6519943372802450 | 618215223791.6519943372802450 | 0.0000000000000000
+ 0.084738 | -10 | 52386321633.6570066961524534 | 52386321633.6570066961524534 | 0.0000000000000000
+ 0.084738 | -9 | 4439112122.5928274334185666 | 4439112122.5928274334185666 | 0.0000000000000000
+ 0.084738 | -8 | 376161483.0442710110530225 | 376161483.0442710110530225 | 0.0000000000000000
+ 0.084738 | -7 | 31875171.7502054369346110 | 31875171.7502054369346110 | 0.0000000000000000
+ 0.084738 | -6 | 2701038.3037689083149651 | 2701038.3037689083149651 | 0.0000000000000000
+ 0.084738 | -5 | 228880.5837847697527935 | 228880.5837847697527935 | 0.0000000000000000
+ 0.084738 | -4 | 19394.8829087538193122 | 19394.8829087538193122 | 0.0000000000000000
+ 0.084738 | -3 | 1643.4835879219811409 | 1643.4835879219811409 | 0.0000000000000000
+ 0.084738 | -2 | 139.2655122733328379 | 139.2655122733328379 | 0.0000000000000000
+ 0.084738 | -1 | 11.8010809790176780 | 11.8010809790176780 | 0.0000000000000000
+ 0.084738 | 0 | 1 | 1.0000000000000000 | 0.0000000000000000
+ 0.084738 | 1 | 0.084738 | 0.0847380000000000 | 0.0000000000000000
+ 0.084738 | 2 | 0.007180528644 | 0.0071805286440000 | 0.0000000000000000
+ 0.084738 | 3 | 0.0006084636362353 | 0.0006084636362353 | 0.0000000000000000
+ 0.084738 | 4 | 0.0000515599916073 | 0.0000515599916073 | 0.0000000000000000
+ 0.084738 | 5 | 0.0000043690905688 | 0.0000043690905688 | 0.0000000000000000
+ 0.084738 | 6 | 0.0000003702279966 | 0.0000003702279966 | 0.0000000000000000
+ 0.084738 | 7 | 0.0000000313723800 | 0.0000000313723800 | 0.0000000000000000
+ 0.084738 | 8 | 0.0000000026584327 | 0.0000000026584327 | 0.0000000000000000
+ 0.084738 | 9 | 0.0000000002252703 | 0.0000000002252703 | 0.0000000000000000
+ 0.084738 | 10 | 0.0000000000190890 | 0.0000000000190890 | 0.0000000000000000
+ 0.084738 | 11 | 0.0000000000016176 | 0.0000000000016176 | 0.0000000000000000
+ 0.084738 | 12 | 0.0000000000001371 | 0.0000000000001371 | 0.0000000000000000
+ 0.084738 | 13 | 0.0000000000000116 | 0.0000000000000116 | 0.0000000000000000
+ 0.084738 | 14 | 0.0000000000000010 | 0.0000000000000010 | 0.0000000000000000
+ 0.084738 | 15 | 0.0000000000000001 | 0.0000000000000001 | 0.0000000000000000
+ 0.084738 | 16 | 0.0000000000000000 | 0.0000000000000000 | 0.0000000000000000
+ 0.084738 | 17 | 0.0000000000000000 | 0.0000000000000000 | 0.0000000000000000
+ 0.084738 | 18 | 0.0000000000000000 | 0.0000000000000000 | 0.0000000000000000
+ 0.084738 | 19 | 0.0000000000000000 | 0.0000000000000000 | 0.0000000000000000
+ 0.084738 | 20 | 0.0000000000000000 | 0.0000000000000000 | 0.0000000000000000
+(41 rows)
+
+-- base greater than 1
+--
+-- bc(1) results computed with a scale of 500 and truncated using the script
+-- below, and then rounded by hand to match the precision of POW():
+--
+-- for p in {-20..20}
+-- do
+-- b="37.821637"
+-- r=$(bc -ql <<< "scale=500 ; $b^$p" | head -n 1)
+-- echo "($b, $p, $r),"
+-- done
+WITH t(b, p, bc_result) AS (VALUES
+(37.821637, -20, .0000000000000000),
+(37.821637, -19, .0000000000000000),
+(37.821637, -18, .0000000000000000),
+(37.821637, -17, .0000000000000000),
+(37.821637, -16, .0000000000000000),
+(37.821637, -15, .0000000000000000),
+(37.821637, -14, .0000000000000000),
+(37.821637, -13, .0000000000000000),
+(37.821637, -12, .0000000000000000),
+(37.821637, -11, .0000000000000000),
+(37.821637, -10, .0000000000000002),
+(37.821637, -9, .0000000000000063),
+(37.821637, -8, .0000000000002388),
+(37.821637, -7, .0000000000090327),
+(37.821637, -6, .0000000003416316),
+(37.821637, -5, .0000000129210673),
+(37.821637, -4, .0000004886959182),
+(37.821637, -3, .0000184832796213),
+(37.821637, -2, .0006990678924066),
+(37.821637, -1, .0264398920649574),
+(37.821637, 0, 1),
+(37.821637, 1, 37.821637),
+(37.821637, 2, 1430.476225359769),
+(37.821637, 3, 54102.9525326873775219),
+(37.821637, 4, 2046262.2313195326271135),
+(37.821637, 5, 77392987.3197773940323425),
+(37.821637, 6, 2927129472.7542235178972258),
+(37.821637, 7, 110708828370.5116321107718772),
+(37.821637, 8, 4187189119324.7924539711577286),
+(37.821637, 9, 158366346921451.9852944363360812),
+(37.821637, 10, 5989674486279224.5007355092228730),
+(37.821637, 11, 226539294168214309.7083246628376531),
+(37.821637, 12, 8568086950266418559.9938312759931069),
+(37.821637, 13, 324059074417413536066.1494087598581043),
+(37.821637, 14, 12256444679171401239980.3109258799733927),
+(37.821637, 15, 463558801566202198479885.2069857662592280),
+(37.821637, 16, 17532552720991931019508170.1002855156233684),
+(37.821637, 17, 663109844696719094948877928.0672523682648687),
+(37.821637, 18, 25079899837245684700124994552.6717306599041850),
+(37.821637, 19, 948562867640665366544581398598.1275771806665398),
+(37.821637, 20, 35876200451584291931921101974730.6901038166532866))
+SELECT b, p, bc_result, b^p AS power, b^p - bc_result AS diff FROM t;
+ b | p | bc_result | power | diff
+-----------+-----+---------------------------------------------------+---------------------------------------------------+--------------------
+ 37.821637 | -20 | 0.0000000000000000 | 0.0000000000000000 | 0.0000000000000000
+ 37.821637 | -19 | 0.0000000000000000 | 0.0000000000000000 | 0.0000000000000000
+ 37.821637 | -18 | 0.0000000000000000 | 0.0000000000000000 | 0.0000000000000000
+ 37.821637 | -17 | 0.0000000000000000 | 0.0000000000000000 | 0.0000000000000000
+ 37.821637 | -16 | 0.0000000000000000 | 0.0000000000000000 | 0.0000000000000000
+ 37.821637 | -15 | 0.0000000000000000 | 0.0000000000000000 | 0.0000000000000000
+ 37.821637 | -14 | 0.0000000000000000 | 0.0000000000000000 | 0.0000000000000000
+ 37.821637 | -13 | 0.0000000000000000 | 0.0000000000000000 | 0.0000000000000000
+ 37.821637 | -12 | 0.0000000000000000 | 0.0000000000000000 | 0.0000000000000000
+ 37.821637 | -11 | 0.0000000000000000 | 0.0000000000000000 | 0.0000000000000000
+ 37.821637 | -10 | 0.0000000000000002 | 0.0000000000000002 | 0.0000000000000000
+ 37.821637 | -9 | 0.0000000000000063 | 0.0000000000000063 | 0.0000000000000000
+ 37.821637 | -8 | 0.0000000000002388 | 0.0000000000002388 | 0.0000000000000000
+ 37.821637 | -7 | 0.0000000000090327 | 0.0000000000090327 | 0.0000000000000000
+ 37.821637 | -6 | 0.0000000003416316 | 0.0000000003416316 | 0.0000000000000000
+ 37.821637 | -5 | 0.0000000129210673 | 0.0000000129210673 | 0.0000000000000000
+ 37.821637 | -4 | 0.0000004886959182 | 0.0000004886959182 | 0.0000000000000000
+ 37.821637 | -3 | 0.0000184832796213 | 0.0000184832796213 | 0.0000000000000000
+ 37.821637 | -2 | 0.0006990678924066 | 0.0006990678924066 | 0.0000000000000000
+ 37.821637 | -1 | 0.0264398920649574 | 0.0264398920649574 | 0.0000000000000000
+ 37.821637 | 0 | 1 | 1.0000000000000000 | 0.0000000000000000
+ 37.821637 | 1 | 37.821637 | 37.8216370000000000 | 0.0000000000000000
+ 37.821637 | 2 | 1430.476225359769 | 1430.4762253597690000 | 0.0000000000000000
+ 37.821637 | 3 | 54102.9525326873775219 | 54102.9525326873775219 | 0.0000000000000000
+ 37.821637 | 4 | 2046262.2313195326271135 | 2046262.2313195326271135 | 0.0000000000000000
+ 37.821637 | 5 | 77392987.3197773940323425 | 77392987.3197773940323425 | 0.0000000000000000
+ 37.821637 | 6 | 2927129472.7542235178972258 | 2927129472.7542235178972258 | 0.0000000000000000
+ 37.821637 | 7 | 110708828370.5116321107718772 | 110708828370.5116321107718772 | 0.0000000000000000
+ 37.821637 | 8 | 4187189119324.7924539711577286 | 4187189119324.7924539711577286 | 0.0000000000000000
+ 37.821637 | 9 | 158366346921451.9852944363360812 | 158366346921451.9852944363360812 | 0.0000000000000000
+ 37.821637 | 10 | 5989674486279224.5007355092228730 | 5989674486279224.5007355092228730 | 0.0000000000000000
+ 37.821637 | 11 | 226539294168214309.7083246628376531 | 226539294168214309.7083246628376531 | 0.0000000000000000
+ 37.821637 | 12 | 8568086950266418559.9938312759931069 | 8568086950266418559.9938312759931069 | 0.0000000000000000
+ 37.821637 | 13 | 324059074417413536066.1494087598581043 | 324059074417413536066.1494087598581043 | 0.0000000000000000
+ 37.821637 | 14 | 12256444679171401239980.3109258799733927 | 12256444679171401239980.3109258799733927 | 0.0000000000000000
+ 37.821637 | 15 | 463558801566202198479885.2069857662592280 | 463558801566202198479885.2069857662592280 | 0.0000000000000000
+ 37.821637 | 16 | 17532552720991931019508170.1002855156233684 | 17532552720991931019508170.1002855156233684 | 0.0000000000000000
+ 37.821637 | 17 | 663109844696719094948877928.0672523682648687 | 663109844696719094948877928.0672523682648687 | 0.0000000000000000
+ 37.821637 | 18 | 25079899837245684700124994552.6717306599041850 | 25079899837245684700124994552.6717306599041850 | 0.0000000000000000
+ 37.821637 | 19 | 948562867640665366544581398598.1275771806665398 | 948562867640665366544581398598.1275771806665398 | 0.0000000000000000
+ 37.821637 | 20 | 35876200451584291931921101974730.6901038166532866 | 35876200451584291931921101974730.6901038166532866 | 0.0000000000000000
+(41 rows)
+
+--
+-- Tests for raising to non-integer powers
+--
+-- base less than 1
+--
+-- bc(1) results computed with a scale of 500 and truncated using the script
+-- below, and then rounded by hand to match the precision of POW():
+--
+-- for n in {-20..20}
+-- do
+-- b="0.06933247"
+-- p="$n.342987"
+-- r=$(bc -ql <<< "scale=500 ; e($p*l($b))" | head -n 1)
+-- echo "($b, $p, $r),"
+-- done
+WITH t(b, p, bc_result) AS (VALUES
+(0.06933247, -20.342987, 379149253615977128356318.39406340),
+(0.06933247, -19.342987, 26287354251852125772450.59436685),
+(0.06933247, -18.342987, 1822567200045909954554.65766042),
+(0.06933247, -17.342987, 126363085720167050546.86216560),
+(0.06933247, -16.342987, 8761064849800910427.02880469),
+(0.06933247, -15.342987, 607426265866876128.15466179),
+(0.06933247, -14.342987, 42114363355427213.14899924),
+(0.06933247, -13.342987, 2919892833909256.59283660),
+(0.06933247, -12.342987, 202443382310228.51544515),
+(0.06933247, -11.342987, 14035899730722.44924025),
+(0.06933247, -10.342987, 973143597003.32229028),
+(0.06933247, -9.342987, 67470449244.92493259),
+(0.06933247, -8.342987, 4677892898.16028054),
+(0.06933247, -7.342987, 324329869.02491071),
+(0.06933247, -6.342987, 22486590.914273551),
+(0.06933247, -5.342987, 1559050.8899661435),
+(0.06933247, -4.342987, 108092.84905705095),
+(0.06933247, -3.342987, 7494.3442144625131),
+(0.06933247, -2.342987, 519.60139541889576),
+(0.06933247, -1.342987, 36.025248159838727),
+(0.06933247, 0.342987, .40036522320023350),
+(0.06933247, 1.342987, .02775830982657349),
+(0.06933247, 2.342987, .001924552183301612),
+(0.06933247, 3.342987, .0001334339565121935),
+(0.06933247, 4.342987, .000009251305786862961),
+(0.06933247, 5.342987, .0000006414158809285026),
+(0.06933247, 6.342987, .00000004447094732199898),
+(0.06933247, 7.342987, .000000003083280621074075),
+(0.06933247, 8.342987, .0000000002137714611621997),
+(0.06933247, 9.342987, .00000000001482130341788437),
+(0.06933247, 10.342987, .000000000001027597574581366),
+(0.06933247, 11.342987, .00000000000007124587801173530),
+(0.06933247, 12.342987, .000000000000004939652699872298),
+(0.06933247, 13.342987, .0000000000000003424783226243151),
+(0.06933247, 14.342987, .00000000000000002374486802900065),
+(0.06933247, 15.342987, .000000000000000001646290350274646),
+(0.06933247, 16.342987, .0000000000000000001141413763217064),
+(0.06933247, 17.342987, .000000000000000000007913703549583420),
+(0.06933247, 18.342987, .0000000000000000000005486766139403860),
+(0.06933247, 19.342987, .00000000000000000000003804110487572339),
+(0.06933247, 20.342987, .000000000000000000000002637483762562946))
+SELECT b, p, bc_result, b^p AS power, b^p - bc_result AS diff FROM t;
+ b | p | bc_result | power | diff
+------------+------------+-------------------------------------------+-------------------------------------------+-------------------------------------------
+ 0.06933247 | -20.342987 | 379149253615977128356318.39406340 | 379149253615977128356318.39406340 | 0.00000000
+ 0.06933247 | -19.342987 | 26287354251852125772450.59436685 | 26287354251852125772450.59436685 | 0.00000000
+ 0.06933247 | -18.342987 | 1822567200045909954554.65766042 | 1822567200045909954554.65766042 | 0.00000000
+ 0.06933247 | -17.342987 | 126363085720167050546.86216560 | 126363085720167050546.86216560 | 0.00000000
+ 0.06933247 | -16.342987 | 8761064849800910427.02880469 | 8761064849800910427.02880469 | 0.00000000
+ 0.06933247 | -15.342987 | 607426265866876128.15466179 | 607426265866876128.15466179 | 0.00000000
+ 0.06933247 | -14.342987 | 42114363355427213.14899924 | 42114363355427213.14899924 | 0.00000000
+ 0.06933247 | -13.342987 | 2919892833909256.59283660 | 2919892833909256.59283660 | 0.00000000
+ 0.06933247 | -12.342987 | 202443382310228.51544515 | 202443382310228.51544515 | 0.00000000
+ 0.06933247 | -11.342987 | 14035899730722.44924025 | 14035899730722.44924025 | 0.00000000
+ 0.06933247 | -10.342987 | 973143597003.32229028 | 973143597003.32229028 | 0.00000000
+ 0.06933247 | -9.342987 | 67470449244.92493259 | 67470449244.92493259 | 0.00000000
+ 0.06933247 | -8.342987 | 4677892898.16028054 | 4677892898.16028054 | 0.00000000
+ 0.06933247 | -7.342987 | 324329869.02491071 | 324329869.02491071 | 0.00000000
+ 0.06933247 | -6.342987 | 22486590.914273551 | 22486590.914273551 | 0.000000000
+ 0.06933247 | -5.342987 | 1559050.8899661435 | 1559050.8899661435 | 0.0000000000
+ 0.06933247 | -4.342987 | 108092.84905705095 | 108092.84905705095 | 0.00000000000
+ 0.06933247 | -3.342987 | 7494.3442144625131 | 7494.3442144625131 | 0.0000000000000
+ 0.06933247 | -2.342987 | 519.60139541889576 | 519.60139541889576 | 0.00000000000000
+ 0.06933247 | -1.342987 | 36.025248159838727 | 36.025248159838727 | 0.000000000000000
+ 0.06933247 | 0.342987 | 0.40036522320023350 | 0.4003652232002335 | 0.00000000000000000
+ 0.06933247 | 1.342987 | 0.02775830982657349 | 0.02775830982657349 | 0.00000000000000000
+ 0.06933247 | 2.342987 | 0.001924552183301612 | 0.001924552183301612 | 0.000000000000000000
+ 0.06933247 | 3.342987 | 0.0001334339565121935 | 0.0001334339565121935 | 0.0000000000000000000
+ 0.06933247 | 4.342987 | 0.000009251305786862961 | 0.000009251305786862961 | 0.000000000000000000000
+ 0.06933247 | 5.342987 | 0.0000006414158809285026 | 0.0000006414158809285026 | 0.0000000000000000000000
+ 0.06933247 | 6.342987 | 0.00000004447094732199898 | 0.00000004447094732199898 | 0.00000000000000000000000
+ 0.06933247 | 7.342987 | 0.000000003083280621074075 | 0.000000003083280621074075 | 0.000000000000000000000000
+ 0.06933247 | 8.342987 | 0.0000000002137714611621997 | 0.0000000002137714611621997 | 0.0000000000000000000000000
+ 0.06933247 | 9.342987 | 0.00000000001482130341788437 | 0.00000000001482130341788437 | 0.00000000000000000000000000
+ 0.06933247 | 10.342987 | 0.000000000001027597574581366 | 0.000000000001027597574581366 | 0.000000000000000000000000000
+ 0.06933247 | 11.342987 | 0.00000000000007124587801173530 | 0.00000000000007124587801173530 | 0.00000000000000000000000000000
+ 0.06933247 | 12.342987 | 0.000000000000004939652699872298 | 0.000000000000004939652699872298 | 0.000000000000000000000000000000
+ 0.06933247 | 13.342987 | 0.0000000000000003424783226243151 | 0.0000000000000003424783226243151 | 0.0000000000000000000000000000000
+ 0.06933247 | 14.342987 | 0.00000000000000002374486802900065 | 0.00000000000000002374486802900065 | 0.00000000000000000000000000000000
+ 0.06933247 | 15.342987 | 0.000000000000000001646290350274646 | 0.000000000000000001646290350274646 | 0.000000000000000000000000000000000
+ 0.06933247 | 16.342987 | 0.0000000000000000001141413763217064 | 0.0000000000000000001141413763217064 | 0.0000000000000000000000000000000000
+ 0.06933247 | 17.342987 | 0.000000000000000000007913703549583420 | 0.000000000000000000007913703549583420 | 0.000000000000000000000000000000000000
+ 0.06933247 | 18.342987 | 0.0000000000000000000005486766139403860 | 0.0000000000000000000005486766139403860 | 0.0000000000000000000000000000000000000
+ 0.06933247 | 19.342987 | 0.00000000000000000000003804110487572339 | 0.00000000000000000000003804110487572339 | 0.00000000000000000000000000000000000000
+ 0.06933247 | 20.342987 | 0.000000000000000000000002637483762562946 | 0.000000000000000000000002637483762562946 | 0.000000000000000000000000000000000000000
+(41 rows)
+
+-- base greater than 1
+--
+-- bc(1) results computed with a scale of 500 and truncated using the script
+-- below, and then rounded by hand to match the precision of POW():
+--
+-- for n in {-20..20}
+-- do
+-- b="27.234987"
+-- p="$n.230957"
+-- r=$(bc -ql <<< "scale=500 ; e($p*l($b))" | head -n 1)
+-- echo "($b, $p, $r),"
+-- done
+WITH t(b, p, bc_result) AS (VALUES
+(27.234987, -20.230957, .000000000000000000000000000009247064512095633),
+(27.234987, -19.230957, .0000000000000000000000000002518436817750859),
+(27.234987, -18.230957, .000000000000000000000000006858959399176602),
+(27.234987, -17.230957, .0000000000000000000000001868036700701026),
+(27.234987, -16.230957, .000000000000000000000005087595525911532),
+(27.234987, -15.230957, .0000000000000000000001385605980094587),
+(27.234987, -14.230957, .000000000000000000003773696085499835),
+(27.234987, -13.230957, .0000000000000000001027765638305389),
+(27.234987, -12.230957, .000000000000000002799118379829397),
+(27.234987, -11.230957, .00000000000000007623395268611469),
+(27.234987, -10.230957, .000000000000002076230710364949),
+(27.234987, -9.230957, .00000000000005654611640579014),
+(27.234987, -8.230957, .000000000001540032745212181),
+(27.234987, -7.230957, .00000000004194277179542807),
+(27.234987, -6.230957, .000000001142310844592450),
+(27.234987, -5.230957, .00000003111082100243440),
+(27.234987, -4.230957, .0000008473028055606278),
+(27.234987, -3.230957, .00002307628089450723),
+(27.234987, -2.230957, .0006284822101702527),
+(27.234987, -1.230957, .01711670482371810),
+(27.234987, 0.230957, 2.1451253063142300),
+(27.234987, 1.230957, 58.422459830839071),
+(27.234987, 2.230957, 1591.1349340009243),
+(27.234987, 3.230957, 43334.539242761031),
+(27.234987, 4.230957, 1180215.6129275865),
+(27.234987, 5.230957, 32143156.875279851),
+(27.234987, 6.230957, 875418459.63720737),
+(27.234987, 7.230957, 23842010367.779367),
+(27.234987, 8.230957, 649336842420.336290),
+(27.234987, 9.230957, 17684680461938.907402),
+(27.234987, 10.230957, 481642042480060.137900),
+(27.234987, 11.230957, 13117514765597885.614921),
+(27.234987, 12.230957, 357255344113366461.949871),
+(27.234987, 13.230957, 9729844652608062117.440722),
+(27.234987, 14.230957, 264992192625800087863.690528),
+(27.234987, 15.230957, 7217058921265161257566.469315),
+(27.234987, 16.230957, 196556505898890690402726.443417),
+(27.234987, 17.230957, 5353213882921711267539279.451015),
+(27.234987, 18.230957, 145794710509592328389185797.837767),
+(27.234987, 19.230957, 3970717045397510438979206144.696206),
+(27.234987, 20.230957, 108142427112079606637962972621.121293))
+SELECT b, p, bc_result, b^p AS power, b^p - bc_result AS diff FROM t;
+ b | p | bc_result | power | diff
+-----------+------------+-------------------------------------------------+-------------------------------------------------+-------------------------------------------------
+ 27.234987 | -20.230957 | 0.000000000000000000000000000009247064512095633 | 0.000000000000000000000000000009247064512095633 | 0.000000000000000000000000000000000000000000000
+ 27.234987 | -19.230957 | 0.0000000000000000000000000002518436817750859 | 0.0000000000000000000000000002518436817750859 | 0.0000000000000000000000000000000000000000000
+ 27.234987 | -18.230957 | 0.000000000000000000000000006858959399176602 | 0.000000000000000000000000006858959399176602 | 0.000000000000000000000000000000000000000000
+ 27.234987 | -17.230957 | 0.0000000000000000000000001868036700701026 | 0.0000000000000000000000001868036700701026 | 0.0000000000000000000000000000000000000000
+ 27.234987 | -16.230957 | 0.000000000000000000000005087595525911532 | 0.000000000000000000000005087595525911532 | 0.000000000000000000000000000000000000000
+ 27.234987 | -15.230957 | 0.0000000000000000000001385605980094587 | 0.0000000000000000000001385605980094587 | 0.0000000000000000000000000000000000000
+ 27.234987 | -14.230957 | 0.000000000000000000003773696085499835 | 0.000000000000000000003773696085499835 | 0.000000000000000000000000000000000000
+ 27.234987 | -13.230957 | 0.0000000000000000001027765638305389 | 0.0000000000000000001027765638305389 | 0.0000000000000000000000000000000000
+ 27.234987 | -12.230957 | 0.000000000000000002799118379829397 | 0.000000000000000002799118379829397 | 0.000000000000000000000000000000000
+ 27.234987 | -11.230957 | 0.00000000000000007623395268611469 | 0.00000000000000007623395268611469 | 0.00000000000000000000000000000000
+ 27.234987 | -10.230957 | 0.000000000000002076230710364949 | 0.000000000000002076230710364949 | 0.000000000000000000000000000000
+ 27.234987 | -9.230957 | 0.00000000000005654611640579014 | 0.00000000000005654611640579014 | 0.00000000000000000000000000000
+ 27.234987 | -8.230957 | 0.000000000001540032745212181 | 0.000000000001540032745212181 | 0.000000000000000000000000000
+ 27.234987 | -7.230957 | 0.00000000004194277179542807 | 0.00000000004194277179542807 | 0.00000000000000000000000000
+ 27.234987 | -6.230957 | 0.000000001142310844592450 | 0.000000001142310844592450 | 0.000000000000000000000000
+ 27.234987 | -5.230957 | 0.00000003111082100243440 | 0.00000003111082100243440 | 0.00000000000000000000000
+ 27.234987 | -4.230957 | 0.0000008473028055606278 | 0.0000008473028055606278 | 0.0000000000000000000000
+ 27.234987 | -3.230957 | 0.00002307628089450723 | 0.00002307628089450723 | 0.00000000000000000000
+ 27.234987 | -2.230957 | 0.0006284822101702527 | 0.0006284822101702527 | 0.0000000000000000000
+ 27.234987 | -1.230957 | 0.01711670482371810 | 0.01711670482371810 | 0.00000000000000000
+ 27.234987 | 0.230957 | 2.1451253063142300 | 2.1451253063142300 | 0.0000000000000000
+ 27.234987 | 1.230957 | 58.422459830839071 | 58.422459830839071 | 0.000000000000000
+ 27.234987 | 2.230957 | 1591.1349340009243 | 1591.1349340009243 | 0.0000000000000
+ 27.234987 | 3.230957 | 43334.539242761031 | 43334.539242761031 | 0.000000000000
+ 27.234987 | 4.230957 | 1180215.6129275865 | 1180215.6129275865 | 0.0000000000
+ 27.234987 | 5.230957 | 32143156.875279851 | 32143156.875279851 | 0.000000000
+ 27.234987 | 6.230957 | 875418459.63720737 | 875418459.63720737 | 0.00000000
+ 27.234987 | 7.230957 | 23842010367.779367 | 23842010367.779367 | 0.000000
+ 27.234987 | 8.230957 | 649336842420.336290 | 649336842420.336290 | 0.000000
+ 27.234987 | 9.230957 | 17684680461938.907402 | 17684680461938.907402 | 0.000000
+ 27.234987 | 10.230957 | 481642042480060.137900 | 481642042480060.137900 | 0.000000
+ 27.234987 | 11.230957 | 13117514765597885.614921 | 13117514765597885.614921 | 0.000000
+ 27.234987 | 12.230957 | 357255344113366461.949871 | 357255344113366461.949871 | 0.000000
+ 27.234987 | 13.230957 | 9729844652608062117.440722 | 9729844652608062117.440722 | 0.000000
+ 27.234987 | 14.230957 | 264992192625800087863.690528 | 264992192625800087863.690528 | 0.000000
+ 27.234987 | 15.230957 | 7217058921265161257566.469315 | 7217058921265161257566.469315 | 0.000000
+ 27.234987 | 16.230957 | 196556505898890690402726.443417 | 196556505898890690402726.443417 | 0.000000
+ 27.234987 | 17.230957 | 5353213882921711267539279.451015 | 5353213882921711267539279.451015 | 0.000000
+ 27.234987 | 18.230957 | 145794710509592328389185797.837767 | 145794710509592328389185797.837767 | 0.000000
+ 27.234987 | 19.230957 | 3970717045397510438979206144.696206 | 3970717045397510438979206144.696206 | 0.000000
+ 27.234987 | 20.230957 | 108142427112079606637962972621.121293 | 108142427112079606637962972621.121293 | 0.000000
+(41 rows)
+
+--
+-- Tests for EXP()
+--
+-- bc(1) results computed with a scale of 500 and truncated using the script
+-- below, and then rounded by hand to match the precision of EXP():
+--
+-- for n in {-20..20}
+-- do
+-- x="$n.29837"
+-- r=$(bc -ql <<< "scale=500 ; e($x)" | head -n 1)
+-- echo "($x, $r),"
+-- done
+WITH t(x, bc_result) AS (VALUES
+(-20.29837, .000000001529431101152222),
+(-19.29837, .000000004157424770142192),
+(-18.29837, .00000001130105220586304),
+(-17.29837, .00000003071944485366452),
+(-16.29837, .00000008350410872606600),
+(-15.29837, .0000002269877013517336),
+(-14.29837, .0000006170165438681061),
+(-13.29837, .000001677224859055276),
+(-12.29837, .000004559169856609741),
+(-11.29837, .00001239310857408049),
+(-10.29837, .00003368796183504298),
+(-9.29837, .00009157337449401917),
+(-8.29837, .0002489222398577673),
+(-7.29837, .0006766408013046928),
+(-6.29837, .001839300394580514),
+(-5.29837, .004999736839665763),
+(-4.29837, .01359069379834070),
+(-3.29837, .03694333598818056),
+(-2.29837, .1004223988993283),
+(-1.29837, .2729763820983097),
+(0.29837, 1.3476603299656679),
+(1.29837, 3.6633205858807959),
+(2.29837, 9.9579377804197108),
+(3.29837, 27.068481317440698),
+(4.29837, 73.579760889182206),
+(5.29837, 200.01052696742555),
+(6.29837, 543.68498095607070),
+(7.29837, 1477.8890041389891),
+(8.29837, 4017.3188244304487),
+(9.29837, 10920.204759575742),
+(10.29837, 29684.194161006717),
+(11.29837, 80690.005580314652),
+(12.29837, 219338.17590722828),
+(13.29837, 596222.97785597218),
+(14.29837, 1620702.0864156289),
+(15.29837, 4405525.0308492653),
+(16.29837, 11975458.636179032),
+(17.29837, 32552671.598188404),
+(18.29837, 88487335.673150406),
+(19.29837, 240533516.60908059),
+(20.29837, 653837887.33381570))
+SELECT x, bc_result, exp(x), exp(x)-bc_result AS diff FROM t;
+ x | bc_result | exp | diff
+-----------+----------------------------+----------------------------+----------------------------
+ -20.29837 | 0.000000001529431101152222 | 0.000000001529431101152222 | 0.000000000000000000000000
+ -19.29837 | 0.000000004157424770142192 | 0.000000004157424770142192 | 0.000000000000000000000000
+ -18.29837 | 0.00000001130105220586304 | 0.00000001130105220586304 | 0.00000000000000000000000
+ -17.29837 | 0.00000003071944485366452 | 0.00000003071944485366452 | 0.00000000000000000000000
+ -16.29837 | 0.00000008350410872606600 | 0.00000008350410872606600 | 0.00000000000000000000000
+ -15.29837 | 0.0000002269877013517336 | 0.0000002269877013517336 | 0.0000000000000000000000
+ -14.29837 | 0.0000006170165438681061 | 0.0000006170165438681061 | 0.0000000000000000000000
+ -13.29837 | 0.000001677224859055276 | 0.000001677224859055276 | 0.000000000000000000000
+ -12.29837 | 0.000004559169856609741 | 0.000004559169856609741 | 0.000000000000000000000
+ -11.29837 | 0.00001239310857408049 | 0.00001239310857408049 | 0.00000000000000000000
+ -10.29837 | 0.00003368796183504298 | 0.00003368796183504298 | 0.00000000000000000000
+ -9.29837 | 0.00009157337449401917 | 0.00009157337449401917 | 0.00000000000000000000
+ -8.29837 | 0.0002489222398577673 | 0.0002489222398577673 | 0.0000000000000000000
+ -7.29837 | 0.0006766408013046928 | 0.0006766408013046928 | 0.0000000000000000000
+ -6.29837 | 0.001839300394580514 | 0.001839300394580514 | 0.000000000000000000
+ -5.29837 | 0.004999736839665763 | 0.004999736839665763 | 0.000000000000000000
+ -4.29837 | 0.01359069379834070 | 0.01359069379834070 | 0.00000000000000000
+ -3.29837 | 0.03694333598818056 | 0.03694333598818056 | 0.00000000000000000
+ -2.29837 | 0.1004223988993283 | 0.1004223988993283 | 0.0000000000000000
+ -1.29837 | 0.2729763820983097 | 0.2729763820983097 | 0.0000000000000000
+ 0.29837 | 1.3476603299656679 | 1.3476603299656679 | 0.0000000000000000
+ 1.29837 | 3.6633205858807959 | 3.6633205858807959 | 0.0000000000000000
+ 2.29837 | 9.9579377804197108 | 9.9579377804197108 | 0.0000000000000000
+ 3.29837 | 27.068481317440698 | 27.068481317440698 | 0.000000000000000
+ 4.29837 | 73.579760889182206 | 73.579760889182206 | 0.000000000000000
+ 5.29837 | 200.01052696742555 | 200.01052696742555 | 0.00000000000000
+ 6.29837 | 543.68498095607070 | 543.68498095607070 | 0.00000000000000
+ 7.29837 | 1477.8890041389891 | 1477.8890041389891 | 0.0000000000000
+ 8.29837 | 4017.3188244304487 | 4017.3188244304487 | 0.0000000000000
+ 9.29837 | 10920.204759575742 | 10920.204759575742 | 0.000000000000
+ 10.29837 | 29684.194161006717 | 29684.194161006717 | 0.000000000000
+ 11.29837 | 80690.005580314652 | 80690.005580314652 | 0.000000000000
+ 12.29837 | 219338.17590722828 | 219338.17590722828 | 0.00000000000
+ 13.29837 | 596222.97785597218 | 596222.97785597218 | 0.00000000000
+ 14.29837 | 1620702.0864156289 | 1620702.0864156289 | 0.0000000000
+ 15.29837 | 4405525.0308492653 | 4405525.0308492653 | 0.0000000000
+ 16.29837 | 11975458.636179032 | 11975458.636179032 | 0.000000000
+ 17.29837 | 32552671.598188404 | 32552671.598188404 | 0.000000000
+ 18.29837 | 88487335.673150406 | 88487335.673150406 | 0.000000000
+ 19.29837 | 240533516.60908059 | 240533516.60908059 | 0.00000000
+ 20.29837 | 653837887.33381570 | 653837887.33381570 | 0.00000000
+(41 rows)
+
+--
+-- Tests for LN()
+--
+-- input very small
+--
+-- bc(1) results computed with a scale of 500 and truncated using the script
+-- below, and then rounded by hand to match the precision of LN():
+--
+-- for p in {1..40}
+-- do
+-- l=$(bc -ql <<< "scale=500 ; l(10^-$p)" | head -n 1)
+-- echo "('1.0e-$p', $l),"
+-- done
+WITH t(x, bc_result) AS (VALUES
+('1.0e-1', -2.3025850929940457),
+('1.0e-2', -4.6051701859880914),
+('1.0e-3', -6.9077552789821371),
+('1.0e-4', -9.2103403719761827),
+('1.0e-5', -11.512925464970228),
+('1.0e-6', -13.815510557964274),
+('1.0e-7', -16.118095650958320),
+('1.0e-8', -18.420680743952365),
+('1.0e-9', -20.723265836946411),
+('1.0e-10', -23.025850929940457),
+('1.0e-11', -25.328436022934503),
+('1.0e-12', -27.631021115928548),
+('1.0e-13', -29.933606208922594),
+('1.0e-14', -32.236191301916640),
+('1.0e-15', -34.5387763949106853),
+('1.0e-16', -36.84136148790473094),
+('1.0e-17', -39.143946580898776628),
+('1.0e-18', -41.4465316738928223123),
+('1.0e-19', -43.74911676688686799634),
+('1.0e-20', -46.051701859880913680360),
+('1.0e-21', -48.3542869528749593643778),
+('1.0e-22', -50.65687204586900504839581),
+('1.0e-23', -52.959457138863050732413803),
+('1.0e-24', -55.2620422318570964164317949),
+('1.0e-25', -57.56462732485114210044978637),
+('1.0e-26', -59.867212417845187784467777822),
+('1.0e-27', -62.1697975108392334684857692765),
+('1.0e-28', -64.47238260383327915250376073116),
+('1.0e-29', -66.774967696827324836521752185847),
+('1.0e-30', -69.0775527898213705205397436405309),
+('1.0e-31', -71.38013788281541620455773509521529),
+('1.0e-32', -73.682722975809461888575726549899655),
+('1.0e-33', -75.9853080688035075725937180045840189),
+('1.0e-34', -78.28789316179755325661170945926838306),
+('1.0e-35', -80.590478254791598940629700913952747266),
+('1.0e-36', -82.8930633477856446246476923686371114736),
+('1.0e-37', -85.19564844077969030866568382332147568124),
+('1.0e-38', -87.498233533773735992683675278005839888842),
+('1.0e-39', -89.8008186267677816767016667326902040964430),
+('1.0e-40', -92.10340371976182736071965818737456830404406))
+SELECT x, bc_result, ln(x::numeric), ln(x::numeric)-bc_result AS diff FROM t;
+ x | bc_result | ln | diff
+---------+-----------------------------------------------+-----------------------------------------------+---------------------------------------------
+ 1.0e-1 | -2.3025850929940457 | -2.3025850929940457 | 0.0000000000000000
+ 1.0e-2 | -4.6051701859880914 | -4.6051701859880914 | 0.0000000000000000
+ 1.0e-3 | -6.9077552789821371 | -6.9077552789821371 | 0.0000000000000000
+ 1.0e-4 | -9.2103403719761827 | -9.2103403719761827 | 0.0000000000000000
+ 1.0e-5 | -11.512925464970228 | -11.512925464970228 | 0.000000000000000
+ 1.0e-6 | -13.815510557964274 | -13.815510557964274 | 0.000000000000000
+ 1.0e-7 | -16.118095650958320 | -16.118095650958320 | 0.000000000000000
+ 1.0e-8 | -18.420680743952365 | -18.420680743952365 | 0.000000000000000
+ 1.0e-9 | -20.723265836946411 | -20.723265836946411 | 0.000000000000000
+ 1.0e-10 | -23.025850929940457 | -23.025850929940457 | 0.000000000000000
+ 1.0e-11 | -25.328436022934503 | -25.328436022934503 | 0.000000000000000
+ 1.0e-12 | -27.631021115928548 | -27.631021115928548 | 0.000000000000000
+ 1.0e-13 | -29.933606208922594 | -29.933606208922594 | 0.000000000000000
+ 1.0e-14 | -32.236191301916640 | -32.236191301916640 | 0.000000000000000
+ 1.0e-15 | -34.5387763949106853 | -34.5387763949106853 | 0.0000000000000000
+ 1.0e-16 | -36.84136148790473094 | -36.84136148790473094 | 0.00000000000000000
+ 1.0e-17 | -39.143946580898776628 | -39.143946580898776628 | 0.000000000000000000
+ 1.0e-18 | -41.4465316738928223123 | -41.4465316738928223123 | 0.0000000000000000000
+ 1.0e-19 | -43.74911676688686799634 | -43.74911676688686799634 | 0.00000000000000000000
+ 1.0e-20 | -46.051701859880913680360 | -46.051701859880913680360 | 0.000000000000000000000
+ 1.0e-21 | -48.3542869528749593643778 | -48.3542869528749593643778 | 0.0000000000000000000000
+ 1.0e-22 | -50.65687204586900504839581 | -50.65687204586900504839581 | 0.00000000000000000000000
+ 1.0e-23 | -52.959457138863050732413803 | -52.959457138863050732413803 | 0.000000000000000000000000
+ 1.0e-24 | -55.2620422318570964164317949 | -55.2620422318570964164317949 | 0.0000000000000000000000000
+ 1.0e-25 | -57.56462732485114210044978637 | -57.56462732485114210044978637 | 0.00000000000000000000000000
+ 1.0e-26 | -59.867212417845187784467777822 | -59.867212417845187784467777822 | 0.000000000000000000000000000
+ 1.0e-27 | -62.1697975108392334684857692765 | -62.1697975108392334684857692765 | 0.0000000000000000000000000000
+ 1.0e-28 | -64.47238260383327915250376073116 | -64.47238260383327915250376073116 | 0.00000000000000000000000000000
+ 1.0e-29 | -66.774967696827324836521752185847 | -66.774967696827324836521752185847 | 0.000000000000000000000000000000
+ 1.0e-30 | -69.0775527898213705205397436405309 | -69.0775527898213705205397436405309 | 0.0000000000000000000000000000000
+ 1.0e-31 | -71.38013788281541620455773509521529 | -71.38013788281541620455773509521529 | 0.00000000000000000000000000000000
+ 1.0e-32 | -73.682722975809461888575726549899655 | -73.682722975809461888575726549899655 | 0.000000000000000000000000000000000
+ 1.0e-33 | -75.9853080688035075725937180045840189 | -75.9853080688035075725937180045840189 | 0.0000000000000000000000000000000000
+ 1.0e-34 | -78.28789316179755325661170945926838306 | -78.28789316179755325661170945926838306 | 0.00000000000000000000000000000000000
+ 1.0e-35 | -80.590478254791598940629700913952747266 | -80.590478254791598940629700913952747266 | 0.000000000000000000000000000000000000
+ 1.0e-36 | -82.8930633477856446246476923686371114736 | -82.8930633477856446246476923686371114736 | 0.0000000000000000000000000000000000000
+ 1.0e-37 | -85.19564844077969030866568382332147568124 | -85.19564844077969030866568382332147568124 | 0.00000000000000000000000000000000000000
+ 1.0e-38 | -87.498233533773735992683675278005839888842 | -87.498233533773735992683675278005839888842 | 0.000000000000000000000000000000000000000
+ 1.0e-39 | -89.8008186267677816767016667326902040964430 | -89.8008186267677816767016667326902040964430 | 0.0000000000000000000000000000000000000000
+ 1.0e-40 | -92.10340371976182736071965818737456830404406 | -92.10340371976182736071965818737456830404406 | 0.00000000000000000000000000000000000000000
+(40 rows)
+
+-- input very close to but smaller than 1
+--
+-- bc(1) results computed with a scale of 500 and truncated using the script
+-- below, and then rounded by hand to match the precision of LN():
+--
+-- for p in {1..40}
+-- do
+-- l=$(bc -ql <<< "scale=500 ; l(1-10^-$p)" | head -n 1)
+-- echo "('1.0e-$p', $l),"
+-- done
+WITH t(x, bc_result) AS (VALUES
+('1.0e-1', -.10536051565782630),
+('1.0e-2', -.010050335853501441),
+('1.0e-3', -.0010005003335835335),
+('1.0e-4', -.00010000500033335834),
+('1.0e-5', -.000010000050000333336),
+('1.0e-6', -.0000010000005000003333),
+('1.0e-7', -.00000010000000500000033),
+('1.0e-8', -.000000010000000050000000),
+('1.0e-9', -.0000000010000000005000000),
+('1.0e-10', -.00000000010000000000500000),
+('1.0e-11', -.000000000010000000000050000),
+('1.0e-12', -.0000000000010000000000005000),
+('1.0e-13', -.00000000000010000000000000500),
+('1.0e-14', -.000000000000010000000000000050),
+('1.0e-15', -.0000000000000010000000000000005),
+('1.0e-16', -.00000000000000010000000000000001),
+('1.0e-17', -.000000000000000010000000000000000),
+('1.0e-18', -.0000000000000000010000000000000000),
+('1.0e-19', -.00000000000000000010000000000000000),
+('1.0e-20', -.000000000000000000010000000000000000),
+('1.0e-21', -.0000000000000000000010000000000000000),
+('1.0e-22', -.00000000000000000000010000000000000000),
+('1.0e-23', -.000000000000000000000010000000000000000),
+('1.0e-24', -.0000000000000000000000010000000000000000),
+('1.0e-25', -.00000000000000000000000010000000000000000),
+('1.0e-26', -.000000000000000000000000010000000000000000),
+('1.0e-27', -.0000000000000000000000000010000000000000000),
+('1.0e-28', -.00000000000000000000000000010000000000000000),
+('1.0e-29', -.000000000000000000000000000010000000000000000),
+('1.0e-30', -.0000000000000000000000000000010000000000000000),
+('1.0e-31', -.00000000000000000000000000000010000000000000000),
+('1.0e-32', -.000000000000000000000000000000010000000000000000),
+('1.0e-33', -.0000000000000000000000000000000010000000000000000),
+('1.0e-34', -.00000000000000000000000000000000010000000000000000),
+('1.0e-35', -.000000000000000000000000000000000010000000000000000),
+('1.0e-36', -.0000000000000000000000000000000000010000000000000000),
+('1.0e-37', -.00000000000000000000000000000000000010000000000000000),
+('1.0e-38', -.000000000000000000000000000000000000010000000000000000),
+('1.0e-39', -.0000000000000000000000000000000000000010000000000000000),
+('1.0e-40', -.00000000000000000000000000000000000000010000000000000000))
+SELECT '1-'||x, bc_result, ln(1.0-x::numeric), ln(1.0-x::numeric)-bc_result AS diff FROM t;
+ ?column? | bc_result | ln | diff
+-----------+-------------------------------------------------------------+-------------------------------------------------------------+------------------------------------------------------------
+ 1-1.0e-1 | -0.10536051565782630 | -0.10536051565782630 | 0.00000000000000000
+ 1-1.0e-2 | -0.010050335853501441 | -0.010050335853501441 | 0.000000000000000000
+ 1-1.0e-3 | -0.0010005003335835335 | -0.0010005003335835335 | 0.0000000000000000000
+ 1-1.0e-4 | -0.00010000500033335834 | -0.00010000500033335834 | 0.00000000000000000000
+ 1-1.0e-5 | -0.000010000050000333336 | -0.000010000050000333336 | 0.000000000000000000000
+ 1-1.0e-6 | -0.0000010000005000003333 | -0.0000010000005000003333 | 0.0000000000000000000000
+ 1-1.0e-7 | -0.00000010000000500000033 | -0.00000010000000500000033 | 0.00000000000000000000000
+ 1-1.0e-8 | -0.000000010000000050000000 | -0.000000010000000050000000 | 0.000000000000000000000000
+ 1-1.0e-9 | -0.0000000010000000005000000 | -0.0000000010000000005000000 | 0.0000000000000000000000000
+ 1-1.0e-10 | -0.00000000010000000000500000 | -0.00000000010000000000500000 | 0.00000000000000000000000000
+ 1-1.0e-11 | -0.000000000010000000000050000 | -0.000000000010000000000050000 | 0.000000000000000000000000000
+ 1-1.0e-12 | -0.0000000000010000000000005000 | -0.0000000000010000000000005000 | 0.0000000000000000000000000000
+ 1-1.0e-13 | -0.00000000000010000000000000500 | -0.00000000000010000000000000500 | 0.00000000000000000000000000000
+ 1-1.0e-14 | -0.000000000000010000000000000050 | -0.000000000000010000000000000050 | 0.000000000000000000000000000000
+ 1-1.0e-15 | -0.0000000000000010000000000000005 | -0.0000000000000010000000000000005 | 0.0000000000000000000000000000000
+ 1-1.0e-16 | -0.00000000000000010000000000000001 | -0.00000000000000010000000000000001 | 0.00000000000000000000000000000000
+ 1-1.0e-17 | -0.000000000000000010000000000000000 | -0.000000000000000010000000000000000 | 0.000000000000000000000000000000000
+ 1-1.0e-18 | -0.0000000000000000010000000000000000 | -0.0000000000000000010000000000000000 | 0.0000000000000000000000000000000000
+ 1-1.0e-19 | -0.00000000000000000010000000000000000 | -0.00000000000000000010000000000000000 | 0.00000000000000000000000000000000000
+ 1-1.0e-20 | -0.000000000000000000010000000000000000 | -0.000000000000000000010000000000000000 | 0.000000000000000000000000000000000000
+ 1-1.0e-21 | -0.0000000000000000000010000000000000000 | -0.0000000000000000000010000000000000000 | 0.0000000000000000000000000000000000000
+ 1-1.0e-22 | -0.00000000000000000000010000000000000000 | -0.00000000000000000000010000000000000000 | 0.00000000000000000000000000000000000000
+ 1-1.0e-23 | -0.000000000000000000000010000000000000000 | -0.000000000000000000000010000000000000000 | 0.000000000000000000000000000000000000000
+ 1-1.0e-24 | -0.0000000000000000000000010000000000000000 | -0.0000000000000000000000010000000000000000 | 0.0000000000000000000000000000000000000000
+ 1-1.0e-25 | -0.00000000000000000000000010000000000000000 | -0.00000000000000000000000010000000000000000 | 0.00000000000000000000000000000000000000000
+ 1-1.0e-26 | -0.000000000000000000000000010000000000000000 | -0.000000000000000000000000010000000000000000 | 0.000000000000000000000000000000000000000000
+ 1-1.0e-27 | -0.0000000000000000000000000010000000000000000 | -0.0000000000000000000000000010000000000000000 | 0.0000000000000000000000000000000000000000000
+ 1-1.0e-28 | -0.00000000000000000000000000010000000000000000 | -0.00000000000000000000000000010000000000000000 | 0.00000000000000000000000000000000000000000000
+ 1-1.0e-29 | -0.000000000000000000000000000010000000000000000 | -0.000000000000000000000000000010000000000000000 | 0.000000000000000000000000000000000000000000000
+ 1-1.0e-30 | -0.0000000000000000000000000000010000000000000000 | -0.0000000000000000000000000000010000000000000000 | 0.0000000000000000000000000000000000000000000000
+ 1-1.0e-31 | -0.00000000000000000000000000000010000000000000000 | -0.00000000000000000000000000000010000000000000000 | 0.00000000000000000000000000000000000000000000000
+ 1-1.0e-32 | -0.000000000000000000000000000000010000000000000000 | -0.000000000000000000000000000000010000000000000000 | 0.000000000000000000000000000000000000000000000000
+ 1-1.0e-33 | -0.0000000000000000000000000000000010000000000000000 | -0.0000000000000000000000000000000010000000000000000 | 0.0000000000000000000000000000000000000000000000000
+ 1-1.0e-34 | -0.00000000000000000000000000000000010000000000000000 | -0.00000000000000000000000000000000010000000000000000 | 0.00000000000000000000000000000000000000000000000000
+ 1-1.0e-35 | -0.000000000000000000000000000000000010000000000000000 | -0.000000000000000000000000000000000010000000000000000 | 0.000000000000000000000000000000000000000000000000000
+ 1-1.0e-36 | -0.0000000000000000000000000000000000010000000000000000 | -0.0000000000000000000000000000000000010000000000000000 | 0.0000000000000000000000000000000000000000000000000000
+ 1-1.0e-37 | -0.00000000000000000000000000000000000010000000000000000 | -0.00000000000000000000000000000000000010000000000000000 | 0.00000000000000000000000000000000000000000000000000000
+ 1-1.0e-38 | -0.000000000000000000000000000000000000010000000000000000 | -0.000000000000000000000000000000000000010000000000000000 | 0.000000000000000000000000000000000000000000000000000000
+ 1-1.0e-39 | -0.0000000000000000000000000000000000000010000000000000000 | -0.0000000000000000000000000000000000000010000000000000000 | 0.0000000000000000000000000000000000000000000000000000000
+ 1-1.0e-40 | -0.00000000000000000000000000000000000000010000000000000000 | -0.00000000000000000000000000000000000000010000000000000000 | 0.00000000000000000000000000000000000000000000000000000000
+(40 rows)
+
+-- input very close to but larger than 1
+--
+-- bc(1) results computed with a scale of 500 and truncated using the script
+-- below, and then rounded by hand to match the precision of LN():
+--
+-- for p in {1..40}
+-- do
+-- l=$(bc -ql <<< "scale=500 ; l(1+10^-$p)" | head -n 1)
+-- echo "('1.0e-$p', $l),"
+-- done
+WITH t(x, bc_result) AS (VALUES
+('1.0e-1', .09531017980432486),
+('1.0e-2', .009950330853168083),
+('1.0e-3', .0009995003330835332),
+('1.0e-4', .00009999500033330834),
+('1.0e-5', .000009999950000333331),
+('1.0e-6', .0000009999995000003333),
+('1.0e-7', .00000009999999500000033),
+('1.0e-8', .000000009999999950000000),
+('1.0e-9', .0000000009999999995000000),
+('1.0e-10', .00000000009999999999500000),
+('1.0e-11', .000000000009999999999950000),
+('1.0e-12', .0000000000009999999999995000),
+('1.0e-13', .00000000000009999999999999500),
+('1.0e-14', .000000000000009999999999999950),
+('1.0e-15', .0000000000000009999999999999995),
+('1.0e-16', .00000000000000010000000000000000),
+('1.0e-17', .000000000000000010000000000000000),
+('1.0e-18', .0000000000000000010000000000000000),
+('1.0e-19', .00000000000000000010000000000000000),
+('1.0e-20', .000000000000000000010000000000000000),
+('1.0e-21', .0000000000000000000010000000000000000),
+('1.0e-22', .00000000000000000000010000000000000000),
+('1.0e-23', .000000000000000000000010000000000000000),
+('1.0e-24', .0000000000000000000000010000000000000000),
+('1.0e-25', .00000000000000000000000010000000000000000),
+('1.0e-26', .000000000000000000000000010000000000000000),
+('1.0e-27', .0000000000000000000000000010000000000000000),
+('1.0e-28', .00000000000000000000000000010000000000000000),
+('1.0e-29', .000000000000000000000000000010000000000000000),
+('1.0e-30', .0000000000000000000000000000010000000000000000),
+('1.0e-31', .00000000000000000000000000000010000000000000000),
+('1.0e-32', .000000000000000000000000000000010000000000000000),
+('1.0e-33', .0000000000000000000000000000000010000000000000000),
+('1.0e-34', .00000000000000000000000000000000010000000000000000),
+('1.0e-35', .000000000000000000000000000000000010000000000000000),
+('1.0e-36', .0000000000000000000000000000000000010000000000000000),
+('1.0e-37', .00000000000000000000000000000000000010000000000000000),
+('1.0e-38', .000000000000000000000000000000000000010000000000000000),
+('1.0e-39', .0000000000000000000000000000000000000010000000000000000),
+('1.0e-40', .00000000000000000000000000000000000000010000000000000000))
+SELECT '1+'||x, bc_result, ln(1.0+x::numeric), ln(1.0+x::numeric)-bc_result AS diff FROM t;
+ ?column? | bc_result | ln | diff
+-----------+------------------------------------------------------------+------------------------------------------------------------+------------------------------------------------------------
+ 1+1.0e-1 | 0.09531017980432486 | 0.09531017980432486 | 0.00000000000000000
+ 1+1.0e-2 | 0.009950330853168083 | 0.009950330853168083 | 0.000000000000000000
+ 1+1.0e-3 | 0.0009995003330835332 | 0.0009995003330835332 | 0.0000000000000000000
+ 1+1.0e-4 | 0.00009999500033330834 | 0.00009999500033330834 | 0.00000000000000000000
+ 1+1.0e-5 | 0.000009999950000333331 | 0.000009999950000333331 | 0.000000000000000000000
+ 1+1.0e-6 | 0.0000009999995000003333 | 0.0000009999995000003333 | 0.0000000000000000000000
+ 1+1.0e-7 | 0.00000009999999500000033 | 0.00000009999999500000033 | 0.00000000000000000000000
+ 1+1.0e-8 | 0.000000009999999950000000 | 0.000000009999999950000000 | 0.000000000000000000000000
+ 1+1.0e-9 | 0.0000000009999999995000000 | 0.0000000009999999995000000 | 0.0000000000000000000000000
+ 1+1.0e-10 | 0.00000000009999999999500000 | 0.00000000009999999999500000 | 0.00000000000000000000000000
+ 1+1.0e-11 | 0.000000000009999999999950000 | 0.000000000009999999999950000 | 0.000000000000000000000000000
+ 1+1.0e-12 | 0.0000000000009999999999995000 | 0.0000000000009999999999995000 | 0.0000000000000000000000000000
+ 1+1.0e-13 | 0.00000000000009999999999999500 | 0.00000000000009999999999999500 | 0.00000000000000000000000000000
+ 1+1.0e-14 | 0.000000000000009999999999999950 | 0.000000000000009999999999999950 | 0.000000000000000000000000000000
+ 1+1.0e-15 | 0.0000000000000009999999999999995 | 0.0000000000000009999999999999995 | 0.0000000000000000000000000000000
+ 1+1.0e-16 | 0.00000000000000010000000000000000 | 0.00000000000000010000000000000000 | 0.00000000000000000000000000000000
+ 1+1.0e-17 | 0.000000000000000010000000000000000 | 0.000000000000000010000000000000000 | 0.000000000000000000000000000000000
+ 1+1.0e-18 | 0.0000000000000000010000000000000000 | 0.0000000000000000010000000000000000 | 0.0000000000000000000000000000000000
+ 1+1.0e-19 | 0.00000000000000000010000000000000000 | 0.00000000000000000010000000000000000 | 0.00000000000000000000000000000000000
+ 1+1.0e-20 | 0.000000000000000000010000000000000000 | 0.000000000000000000010000000000000000 | 0.000000000000000000000000000000000000
+ 1+1.0e-21 | 0.0000000000000000000010000000000000000 | 0.0000000000000000000010000000000000000 | 0.0000000000000000000000000000000000000
+ 1+1.0e-22 | 0.00000000000000000000010000000000000000 | 0.00000000000000000000010000000000000000 | 0.00000000000000000000000000000000000000
+ 1+1.0e-23 | 0.000000000000000000000010000000000000000 | 0.000000000000000000000010000000000000000 | 0.000000000000000000000000000000000000000
+ 1+1.0e-24 | 0.0000000000000000000000010000000000000000 | 0.0000000000000000000000010000000000000000 | 0.0000000000000000000000000000000000000000
+ 1+1.0e-25 | 0.00000000000000000000000010000000000000000 | 0.00000000000000000000000010000000000000000 | 0.00000000000000000000000000000000000000000
+ 1+1.0e-26 | 0.000000000000000000000000010000000000000000 | 0.000000000000000000000000010000000000000000 | 0.000000000000000000000000000000000000000000
+ 1+1.0e-27 | 0.0000000000000000000000000010000000000000000 | 0.0000000000000000000000000010000000000000000 | 0.0000000000000000000000000000000000000000000
+ 1+1.0e-28 | 0.00000000000000000000000000010000000000000000 | 0.00000000000000000000000000010000000000000000 | 0.00000000000000000000000000000000000000000000
+ 1+1.0e-29 | 0.000000000000000000000000000010000000000000000 | 0.000000000000000000000000000010000000000000000 | 0.000000000000000000000000000000000000000000000
+ 1+1.0e-30 | 0.0000000000000000000000000000010000000000000000 | 0.0000000000000000000000000000010000000000000000 | 0.0000000000000000000000000000000000000000000000
+ 1+1.0e-31 | 0.00000000000000000000000000000010000000000000000 | 0.00000000000000000000000000000010000000000000000 | 0.00000000000000000000000000000000000000000000000
+ 1+1.0e-32 | 0.000000000000000000000000000000010000000000000000 | 0.000000000000000000000000000000010000000000000000 | 0.000000000000000000000000000000000000000000000000
+ 1+1.0e-33 | 0.0000000000000000000000000000000010000000000000000 | 0.0000000000000000000000000000000010000000000000000 | 0.0000000000000000000000000000000000000000000000000
+ 1+1.0e-34 | 0.00000000000000000000000000000000010000000000000000 | 0.00000000000000000000000000000000010000000000000000 | 0.00000000000000000000000000000000000000000000000000
+ 1+1.0e-35 | 0.000000000000000000000000000000000010000000000000000 | 0.000000000000000000000000000000000010000000000000000 | 0.000000000000000000000000000000000000000000000000000
+ 1+1.0e-36 | 0.0000000000000000000000000000000000010000000000000000 | 0.0000000000000000000000000000000000010000000000000000 | 0.0000000000000000000000000000000000000000000000000000
+ 1+1.0e-37 | 0.00000000000000000000000000000000000010000000000000000 | 0.00000000000000000000000000000000000010000000000000000 | 0.00000000000000000000000000000000000000000000000000000
+ 1+1.0e-38 | 0.000000000000000000000000000000000000010000000000000000 | 0.000000000000000000000000000000000000010000000000000000 | 0.000000000000000000000000000000000000000000000000000000
+ 1+1.0e-39 | 0.0000000000000000000000000000000000000010000000000000000 | 0.0000000000000000000000000000000000000010000000000000000 | 0.0000000000000000000000000000000000000000000000000000000
+ 1+1.0e-40 | 0.00000000000000000000000000000000000000010000000000000000 | 0.00000000000000000000000000000000000000010000000000000000 | 0.00000000000000000000000000000000000000000000000000000000
+(40 rows)
+
+-- input very large
+--
+-- bc(1) results computed with a scale of 500 and truncated using the script
+-- below, and then rounded by hand to match the precision of LN():
+--
+-- for p in {1..40}
+-- do
+-- l=$(bc -ql <<< "scale=500 ; l(10^$p)" | head -n 1)
+-- echo "('1.0e$p', $l),"
+-- done
+WITH t(x, bc_result) AS (VALUES
+('1.0e1', 2.3025850929940457),
+('1.0e2', 4.6051701859880914),
+('1.0e3', 6.9077552789821371),
+('1.0e4', 9.2103403719761827),
+('1.0e5', 11.512925464970228),
+('1.0e6', 13.815510557964274),
+('1.0e7', 16.118095650958320),
+('1.0e8', 18.420680743952365),
+('1.0e9', 20.723265836946411),
+('1.0e10', 23.025850929940457),
+('1.0e11', 25.328436022934503),
+('1.0e12', 27.631021115928548),
+('1.0e13', 29.933606208922594),
+('1.0e14', 32.236191301916640),
+('1.0e15', 34.538776394910685),
+('1.0e16', 36.841361487904731),
+('1.0e17', 39.143946580898777),
+('1.0e18', 41.446531673892822),
+('1.0e19', 43.749116766886868),
+('1.0e20', 46.051701859880914),
+('1.0e21', 48.354286952874959),
+('1.0e22', 50.656872045869005),
+('1.0e23', 52.959457138863051),
+('1.0e24', 55.262042231857096),
+('1.0e25', 57.564627324851142),
+('1.0e26', 59.867212417845188),
+('1.0e27', 62.169797510839233),
+('1.0e28', 64.472382603833279),
+('1.0e29', 66.774967696827325),
+('1.0e30', 69.077552789821371),
+('1.0e31', 71.380137882815416),
+('1.0e32', 73.682722975809462),
+('1.0e33', 75.985308068803508),
+('1.0e34', 78.287893161797553),
+('1.0e35', 80.590478254791599),
+('1.0e36', 82.893063347785645),
+('1.0e37', 85.195648440779690),
+('1.0e38', 87.498233533773736),
+('1.0e39', 89.800818626767782),
+('1.0e40', 92.103403719761827))
+SELECT x, bc_result, ln(x::numeric), ln(x::numeric)-bc_result AS diff FROM t;
+ x | bc_result | ln | diff
+--------+--------------------+--------------------+--------------------
+ 1.0e1 | 2.3025850929940457 | 2.3025850929940457 | 0.0000000000000000
+ 1.0e2 | 4.6051701859880914 | 4.6051701859880914 | 0.0000000000000000
+ 1.0e3 | 6.9077552789821371 | 6.9077552789821371 | 0.0000000000000000
+ 1.0e4 | 9.2103403719761827 | 9.2103403719761827 | 0.0000000000000000
+ 1.0e5 | 11.512925464970228 | 11.512925464970228 | 0.000000000000000
+ 1.0e6 | 13.815510557964274 | 13.815510557964274 | 0.000000000000000
+ 1.0e7 | 16.118095650958320 | 16.118095650958320 | 0.000000000000000
+ 1.0e8 | 18.420680743952365 | 18.420680743952365 | 0.000000000000000
+ 1.0e9 | 20.723265836946411 | 20.723265836946411 | 0.000000000000000
+ 1.0e10 | 23.025850929940457 | 23.025850929940457 | 0.000000000000000
+ 1.0e11 | 25.328436022934503 | 25.328436022934503 | 0.000000000000000
+ 1.0e12 | 27.631021115928548 | 27.631021115928548 | 0.000000000000000
+ 1.0e13 | 29.933606208922594 | 29.933606208922594 | 0.000000000000000
+ 1.0e14 | 32.236191301916640 | 32.236191301916640 | 0.000000000000000
+ 1.0e15 | 34.538776394910685 | 34.538776394910685 | 0.000000000000000
+ 1.0e16 | 36.841361487904731 | 36.841361487904731 | 0.000000000000000
+ 1.0e17 | 39.143946580898777 | 39.143946580898777 | 0.000000000000000
+ 1.0e18 | 41.446531673892822 | 41.446531673892822 | 0.000000000000000
+ 1.0e19 | 43.749116766886868 | 43.749116766886868 | 0.000000000000000
+ 1.0e20 | 46.051701859880914 | 46.051701859880914 | 0.000000000000000
+ 1.0e21 | 48.354286952874959 | 48.354286952874959 | 0.000000000000000
+ 1.0e22 | 50.656872045869005 | 50.656872045869005 | 0.000000000000000
+ 1.0e23 | 52.959457138863051 | 52.959457138863051 | 0.000000000000000
+ 1.0e24 | 55.262042231857096 | 55.262042231857096 | 0.000000000000000
+ 1.0e25 | 57.564627324851142 | 57.564627324851142 | 0.000000000000000
+ 1.0e26 | 59.867212417845188 | 59.867212417845188 | 0.000000000000000
+ 1.0e27 | 62.169797510839233 | 62.169797510839233 | 0.000000000000000
+ 1.0e28 | 64.472382603833279 | 64.472382603833279 | 0.000000000000000
+ 1.0e29 | 66.774967696827325 | 66.774967696827325 | 0.000000000000000
+ 1.0e30 | 69.077552789821371 | 69.077552789821371 | 0.000000000000000
+ 1.0e31 | 71.380137882815416 | 71.380137882815416 | 0.000000000000000
+ 1.0e32 | 73.682722975809462 | 73.682722975809462 | 0.000000000000000
+ 1.0e33 | 75.985308068803508 | 75.985308068803508 | 0.000000000000000
+ 1.0e34 | 78.287893161797553 | 78.287893161797553 | 0.000000000000000
+ 1.0e35 | 80.590478254791599 | 80.590478254791599 | 0.000000000000000
+ 1.0e36 | 82.893063347785645 | 82.893063347785645 | 0.000000000000000
+ 1.0e37 | 85.195648440779690 | 85.195648440779690 | 0.000000000000000
+ 1.0e38 | 87.498233533773736 | 87.498233533773736 | 0.000000000000000
+ 1.0e39 | 89.800818626767782 | 89.800818626767782 | 0.000000000000000
+ 1.0e40 | 92.103403719761827 | 92.103403719761827 | 0.000000000000000
+(40 rows)
+
+-- input huge
+--
+-- bc(1) results computed with a scale of 1000 and truncated using the script
+-- below, and then rounded by hand to match the precision of LN():
+--
+-- for p in {1..10}
+-- do
+-- l=$(bc -ql <<< "scale=1000 ; l(10^${p}00)" | head -n 1)
+-- echo "('1.0e${p}00', $l),"
+-- done
+WITH t(x, bc_result) AS (VALUES
+('1.0e100', 230.25850929940457),
+('1.0e200', 460.51701859880914),
+('1.0e300', 690.77552789821371),
+('1.0e400', 921.03403719761827),
+('1.0e500', 1151.2925464970228),
+('1.0e600', 1381.5510557964274),
+('1.0e700', 1611.8095650958320),
+('1.0e800', 1842.0680743952365),
+('1.0e900', 2072.3265836946411),
+('1.0e1000', 2302.5850929940457))
+SELECT x, bc_result, ln(x::numeric), ln(x::numeric)-bc_result AS diff FROM t;
+ x | bc_result | ln | diff
+----------+--------------------+--------------------+------------------
+ 1.0e100 | 230.25850929940457 | 230.25850929940457 | 0.00000000000000
+ 1.0e200 | 460.51701859880914 | 460.51701859880914 | 0.00000000000000
+ 1.0e300 | 690.77552789821371 | 690.77552789821371 | 0.00000000000000
+ 1.0e400 | 921.03403719761827 | 921.03403719761827 | 0.00000000000000
+ 1.0e500 | 1151.2925464970228 | 1151.2925464970228 | 0.0000000000000
+ 1.0e600 | 1381.5510557964274 | 1381.5510557964274 | 0.0000000000000
+ 1.0e700 | 1611.8095650958320 | 1611.8095650958320 | 0.0000000000000
+ 1.0e800 | 1842.0680743952365 | 1842.0680743952365 | 0.0000000000000
+ 1.0e900 | 2072.3265836946411 | 2072.3265836946411 | 0.0000000000000
+ 1.0e1000 | 2302.5850929940457 | 2302.5850929940457 | 0.0000000000000
+(10 rows)
+
+--
+-- Tests for LOG() (base 10)
+--
+-- input very small, exact result known
+WITH t(x) AS (SELECT '1e-'||n FROM generate_series(1, 100) g(n))
+SELECT x, log(x::numeric) FROM t;
+ x | log
+--------+-----------------------------------------------------------------------------------------------------------
+ 1e-1 | -1.0000000000000000
+ 1e-2 | -2.0000000000000000
+ 1e-3 | -3.0000000000000000
+ 1e-4 | -4.0000000000000000
+ 1e-5 | -5.000000000000000
+ 1e-6 | -6.000000000000000
+ 1e-7 | -7.000000000000000
+ 1e-8 | -8.000000000000000
+ 1e-9 | -9.000000000000000
+ 1e-10 | -10.000000000000000
+ 1e-11 | -11.000000000000000
+ 1e-12 | -12.000000000000000
+ 1e-13 | -13.000000000000000
+ 1e-14 | -14.000000000000000
+ 1e-15 | -15.000000000000000
+ 1e-16 | -16.0000000000000000
+ 1e-17 | -17.00000000000000000
+ 1e-18 | -18.000000000000000000
+ 1e-19 | -19.0000000000000000000
+ 1e-20 | -20.00000000000000000000
+ 1e-21 | -21.000000000000000000000
+ 1e-22 | -22.0000000000000000000000
+ 1e-23 | -23.00000000000000000000000
+ 1e-24 | -24.000000000000000000000000
+ 1e-25 | -25.0000000000000000000000000
+ 1e-26 | -26.00000000000000000000000000
+ 1e-27 | -27.000000000000000000000000000
+ 1e-28 | -28.0000000000000000000000000000
+ 1e-29 | -29.00000000000000000000000000000
+ 1e-30 | -30.000000000000000000000000000000
+ 1e-31 | -31.0000000000000000000000000000000
+ 1e-32 | -32.00000000000000000000000000000000
+ 1e-33 | -33.000000000000000000000000000000000
+ 1e-34 | -34.0000000000000000000000000000000000
+ 1e-35 | -35.00000000000000000000000000000000000
+ 1e-36 | -36.000000000000000000000000000000000000
+ 1e-37 | -37.0000000000000000000000000000000000000
+ 1e-38 | -38.00000000000000000000000000000000000000
+ 1e-39 | -39.000000000000000000000000000000000000000
+ 1e-40 | -40.0000000000000000000000000000000000000000
+ 1e-41 | -41.00000000000000000000000000000000000000000
+ 1e-42 | -42.000000000000000000000000000000000000000000
+ 1e-43 | -43.0000000000000000000000000000000000000000000
+ 1e-44 | -44.00000000000000000000000000000000000000000000
+ 1e-45 | -45.000000000000000000000000000000000000000000000
+ 1e-46 | -46.0000000000000000000000000000000000000000000000
+ 1e-47 | -47.00000000000000000000000000000000000000000000000
+ 1e-48 | -48.000000000000000000000000000000000000000000000000
+ 1e-49 | -49.0000000000000000000000000000000000000000000000000
+ 1e-50 | -50.00000000000000000000000000000000000000000000000000
+ 1e-51 | -51.000000000000000000000000000000000000000000000000000
+ 1e-52 | -52.0000000000000000000000000000000000000000000000000000
+ 1e-53 | -53.00000000000000000000000000000000000000000000000000000
+ 1e-54 | -54.000000000000000000000000000000000000000000000000000000
+ 1e-55 | -55.0000000000000000000000000000000000000000000000000000000
+ 1e-56 | -56.00000000000000000000000000000000000000000000000000000000
+ 1e-57 | -57.000000000000000000000000000000000000000000000000000000000
+ 1e-58 | -58.0000000000000000000000000000000000000000000000000000000000
+ 1e-59 | -59.00000000000000000000000000000000000000000000000000000000000
+ 1e-60 | -60.000000000000000000000000000000000000000000000000000000000000
+ 1e-61 | -61.0000000000000000000000000000000000000000000000000000000000000
+ 1e-62 | -62.00000000000000000000000000000000000000000000000000000000000000
+ 1e-63 | -63.000000000000000000000000000000000000000000000000000000000000000
+ 1e-64 | -64.0000000000000000000000000000000000000000000000000000000000000000
+ 1e-65 | -65.00000000000000000000000000000000000000000000000000000000000000000
+ 1e-66 | -66.000000000000000000000000000000000000000000000000000000000000000000
+ 1e-67 | -67.0000000000000000000000000000000000000000000000000000000000000000000
+ 1e-68 | -68.00000000000000000000000000000000000000000000000000000000000000000000
+ 1e-69 | -69.000000000000000000000000000000000000000000000000000000000000000000000
+ 1e-70 | -70.0000000000000000000000000000000000000000000000000000000000000000000000
+ 1e-71 | -71.00000000000000000000000000000000000000000000000000000000000000000000000
+ 1e-72 | -72.000000000000000000000000000000000000000000000000000000000000000000000000
+ 1e-73 | -73.0000000000000000000000000000000000000000000000000000000000000000000000000
+ 1e-74 | -74.00000000000000000000000000000000000000000000000000000000000000000000000000
+ 1e-75 | -75.000000000000000000000000000000000000000000000000000000000000000000000000000
+ 1e-76 | -76.0000000000000000000000000000000000000000000000000000000000000000000000000000
+ 1e-77 | -77.00000000000000000000000000000000000000000000000000000000000000000000000000000
+ 1e-78 | -78.000000000000000000000000000000000000000000000000000000000000000000000000000000
+ 1e-79 | -79.0000000000000000000000000000000000000000000000000000000000000000000000000000000
+ 1e-80 | -80.00000000000000000000000000000000000000000000000000000000000000000000000000000000
+ 1e-81 | -81.000000000000000000000000000000000000000000000000000000000000000000000000000000000
+ 1e-82 | -82.0000000000000000000000000000000000000000000000000000000000000000000000000000000000
+ 1e-83 | -83.00000000000000000000000000000000000000000000000000000000000000000000000000000000000
+ 1e-84 | -84.000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+ 1e-85 | -85.0000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+ 1e-86 | -86.00000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+ 1e-87 | -87.000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+ 1e-88 | -88.0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+ 1e-89 | -89.00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+ 1e-90 | -90.000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+ 1e-91 | -91.0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+ 1e-92 | -92.00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+ 1e-93 | -93.000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+ 1e-94 | -94.0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+ 1e-95 | -95.00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+ 1e-96 | -96.000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+ 1e-97 | -97.0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+ 1e-98 | -98.00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+ 1e-99 | -99.000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+ 1e-100 | -100.0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+(100 rows)
+
+-- input very small, non-exact results
+--
+-- bc(1) results computed with a scale of 500 and truncated using the script
+-- below, and then rounded by hand to match the precision of LN():
+--
+-- for p in {1..50..7}
+-- do
+-- for d in {9..1..3}
+-- do
+-- l=$(bc -ql <<< "scale=500 ; l($d*10^-$p) / l(10)" | head -n 1)
+-- echo "('${d}.0e-$p', $l),"
+-- done
+-- done
+WITH t(x, bc_result) AS (VALUES
+('9.0e-1', -.04575749056067513),
+('6.0e-1', -.2218487496163564),
+('3.0e-1', -.5228787452803376),
+('9.0e-8', -7.045757490560675),
+('6.0e-8', -7.221848749616356),
+('3.0e-8', -7.522878745280338),
+('9.0e-15', -14.0457574905606751),
+('6.0e-15', -14.2218487496163564),
+('3.0e-15', -14.5228787452803376),
+('9.0e-22', -21.04575749056067512540994),
+('6.0e-22', -21.22184874961635636749123),
+('3.0e-22', -21.52287874528033756270497),
+('9.0e-29', -28.045757490560675125409944193490),
+('6.0e-29', -28.221848749616356367491233202020),
+('3.0e-29', -28.522878745280337562704972096745),
+('9.0e-36', -35.0457574905606751254099441934897693816),
+('6.0e-36', -35.2218487496163563674912332020203916640),
+('3.0e-36', -35.5228787452803375627049720967448846908),
+('9.0e-43', -42.04575749056067512540994419348976938159974227),
+('6.0e-43', -42.22184874961635636749123320202039166403168125),
+('3.0e-43', -42.52287874528033756270497209674488469079987114),
+('9.0e-50', -49.045757490560675125409944193489769381599742271618608),
+('6.0e-50', -49.221848749616356367491233202020391664031681254347196),
+('3.0e-50', -49.522878745280337562704972096744884690799871135809304))
+SELECT x, bc_result, log(x::numeric), log(x::numeric)-bc_result AS diff FROM t;
+ x | bc_result | log | diff
+---------+---------------------------------------------------------+---------------------------------------------------------+-------------------------------------------------------
+ 9.0e-1 | -0.04575749056067513 | -0.04575749056067513 | 0.00000000000000000
+ 6.0e-1 | -0.2218487496163564 | -0.2218487496163564 | 0.0000000000000000
+ 3.0e-1 | -0.5228787452803376 | -0.5228787452803376 | 0.0000000000000000
+ 9.0e-8 | -7.045757490560675 | -7.045757490560675 | 0.000000000000000
+ 6.0e-8 | -7.221848749616356 | -7.221848749616356 | 0.000000000000000
+ 3.0e-8 | -7.522878745280338 | -7.522878745280338 | 0.000000000000000
+ 9.0e-15 | -14.0457574905606751 | -14.0457574905606751 | 0.0000000000000000
+ 6.0e-15 | -14.2218487496163564 | -14.2218487496163564 | 0.0000000000000000
+ 3.0e-15 | -14.5228787452803376 | -14.5228787452803376 | 0.0000000000000000
+ 9.0e-22 | -21.04575749056067512540994 | -21.04575749056067512540994 | 0.00000000000000000000000
+ 6.0e-22 | -21.22184874961635636749123 | -21.22184874961635636749123 | 0.00000000000000000000000
+ 3.0e-22 | -21.52287874528033756270497 | -21.52287874528033756270497 | 0.00000000000000000000000
+ 9.0e-29 | -28.045757490560675125409944193490 | -28.045757490560675125409944193490 | 0.000000000000000000000000000000
+ 6.0e-29 | -28.221848749616356367491233202020 | -28.221848749616356367491233202020 | 0.000000000000000000000000000000
+ 3.0e-29 | -28.522878745280337562704972096745 | -28.522878745280337562704972096745 | 0.000000000000000000000000000000
+ 9.0e-36 | -35.0457574905606751254099441934897693816 | -35.0457574905606751254099441934897693816 | 0.0000000000000000000000000000000000000
+ 6.0e-36 | -35.2218487496163563674912332020203916640 | -35.2218487496163563674912332020203916640 | 0.0000000000000000000000000000000000000
+ 3.0e-36 | -35.5228787452803375627049720967448846908 | -35.5228787452803375627049720967448846908 | 0.0000000000000000000000000000000000000
+ 9.0e-43 | -42.04575749056067512540994419348976938159974227 | -42.04575749056067512540994419348976938159974227 | 0.00000000000000000000000000000000000000000000
+ 6.0e-43 | -42.22184874961635636749123320202039166403168125 | -42.22184874961635636749123320202039166403168125 | 0.00000000000000000000000000000000000000000000
+ 3.0e-43 | -42.52287874528033756270497209674488469079987114 | -42.52287874528033756270497209674488469079987114 | 0.00000000000000000000000000000000000000000000
+ 9.0e-50 | -49.045757490560675125409944193489769381599742271618608 | -49.045757490560675125409944193489769381599742271618608 | 0.000000000000000000000000000000000000000000000000000
+ 6.0e-50 | -49.221848749616356367491233202020391664031681254347196 | -49.221848749616356367491233202020391664031681254347196 | 0.000000000000000000000000000000000000000000000000000
+ 3.0e-50 | -49.522878745280337562704972096744884690799871135809304 | -49.522878745280337562704972096744884690799871135809304 | 0.000000000000000000000000000000000000000000000000000
+(24 rows)
+
+-- input very close to but smaller than 1
+--
+-- bc(1) results computed with a scale of 500 and truncated using the script
+-- below, and then rounded by hand to match the precision of LN():
+--
+-- for p in {1..40..7}
+-- do
+-- for d in {9..1..3}
+-- do
+-- l=$(bc -ql <<< "scale=500 ; l(1-$d*10^-$p) / l(10)" | head -n 1)
+-- echo "('${d}.0e-$p', $l),"
+-- done
+-- done
+WITH t(x, bc_result) AS (VALUES
+('9.0e-1', -1.0000000000000000),
+('6.0e-1', -.3979400086720376),
+('3.0e-1', -.1549019599857432),
+('9.0e-8', -.000000039086505130185422),
+('6.0e-8', -.000000026057669695925208),
+('3.0e-8', -.000000013028834652530076),
+('9.0e-15', -.0000000000000039086503371292840),
+('6.0e-15', -.0000000000000026057668914195188),
+('3.0e-15', -.0000000000000013028834457097574),
+('9.0e-22', -.00000000000000000000039086503371292664),
+('6.0e-22', -.00000000000000000000026057668914195110),
+('3.0e-22', -.00000000000000000000013028834457097555),
+('9.0e-29', -.000000000000000000000000000039086503371292664),
+('6.0e-29', -.000000000000000000000000000026057668914195110),
+('3.0e-29', -.000000000000000000000000000013028834457097555),
+('9.0e-36', -.0000000000000000000000000000000000039086503371292664),
+('6.0e-36', -.0000000000000000000000000000000000026057668914195110),
+('3.0e-36', -.0000000000000000000000000000000000013028834457097555))
+SELECT '1-'||x, bc_result, log(1.0-x::numeric), log(1.0-x::numeric)-bc_result AS diff FROM t;
+ ?column? | bc_result | log | diff
+-----------+---------------------------------------------------------+---------------------------------------------------------+--------------------------------------------------------
+ 1-9.0e-1 | -1.0000000000000000 | -1.0000000000000000 | 0.0000000000000000
+ 1-6.0e-1 | -0.3979400086720376 | -0.3979400086720376 | 0.0000000000000000
+ 1-3.0e-1 | -0.1549019599857432 | -0.1549019599857432 | 0.0000000000000000
+ 1-9.0e-8 | -0.000000039086505130185422 | -0.000000039086505130185422 | 0.000000000000000000000000
+ 1-6.0e-8 | -0.000000026057669695925208 | -0.000000026057669695925208 | 0.000000000000000000000000
+ 1-3.0e-8 | -0.000000013028834652530076 | -0.000000013028834652530076 | 0.000000000000000000000000
+ 1-9.0e-15 | -0.0000000000000039086503371292840 | -0.0000000000000039086503371292840 | 0.0000000000000000000000000000000
+ 1-6.0e-15 | -0.0000000000000026057668914195188 | -0.0000000000000026057668914195188 | 0.0000000000000000000000000000000
+ 1-3.0e-15 | -0.0000000000000013028834457097574 | -0.0000000000000013028834457097574 | 0.0000000000000000000000000000000
+ 1-9.0e-22 | -0.00000000000000000000039086503371292664 | -0.00000000000000000000039086503371292664 | 0.00000000000000000000000000000000000000
+ 1-6.0e-22 | -0.00000000000000000000026057668914195110 | -0.00000000000000000000026057668914195110 | 0.00000000000000000000000000000000000000
+ 1-3.0e-22 | -0.00000000000000000000013028834457097555 | -0.00000000000000000000013028834457097555 | 0.00000000000000000000000000000000000000
+ 1-9.0e-29 | -0.000000000000000000000000000039086503371292664 | -0.000000000000000000000000000039086503371292664 | 0.000000000000000000000000000000000000000000000
+ 1-6.0e-29 | -0.000000000000000000000000000026057668914195110 | -0.000000000000000000000000000026057668914195110 | 0.000000000000000000000000000000000000000000000
+ 1-3.0e-29 | -0.000000000000000000000000000013028834457097555 | -0.000000000000000000000000000013028834457097555 | 0.000000000000000000000000000000000000000000000
+ 1-9.0e-36 | -0.0000000000000000000000000000000000039086503371292664 | -0.0000000000000000000000000000000000039086503371292664 | 0.0000000000000000000000000000000000000000000000000000
+ 1-6.0e-36 | -0.0000000000000000000000000000000000026057668914195110 | -0.0000000000000000000000000000000000026057668914195110 | 0.0000000000000000000000000000000000000000000000000000
+ 1-3.0e-36 | -0.0000000000000000000000000000000000013028834457097555 | -0.0000000000000000000000000000000000013028834457097555 | 0.0000000000000000000000000000000000000000000000000000
+(18 rows)
+
+-- input very close to but larger than 1
+--
+-- bc(1) results computed with a scale of 500 and truncated using the script
+-- below, and then rounded by hand to match the precision of LN():
+--
+-- for p in {1..40..7}
+-- do
+-- for d in {9..1..3}
+-- do
+-- l=$(bc -ql <<< "scale=500 ; l(1+$d*10^-$p) / l(10)" | head -n 1)
+-- echo "('${d}.0e-$p', $l),"
+-- done
+-- done
+WITH t(x, bc_result) AS (VALUES
+('9.0e-1', .2787536009528290),
+('6.0e-1', .2041199826559248),
+('3.0e-1', .1139433523068368),
+('9.0e-8', .000000039086501612400118),
+('6.0e-8', .000000026057668132465074),
+('3.0e-8', .000000013028834261665042),
+('9.0e-15', .0000000000000039086503371292489),
+('6.0e-15', .0000000000000026057668914195031),
+('3.0e-15', .0000000000000013028834457097535),
+('9.0e-22', .00000000000000000000039086503371292664),
+('6.0e-22', .00000000000000000000026057668914195110),
+('3.0e-22', .00000000000000000000013028834457097555),
+('9.0e-29', .000000000000000000000000000039086503371292664),
+('6.0e-29', .000000000000000000000000000026057668914195110),
+('3.0e-29', .000000000000000000000000000013028834457097555),
+('9.0e-36', .0000000000000000000000000000000000039086503371292664),
+('6.0e-36', .0000000000000000000000000000000000026057668914195110),
+('3.0e-36', .0000000000000000000000000000000000013028834457097555))
+SELECT '1+'||x, bc_result, log(1.0+x::numeric), log(1.0+x::numeric)-bc_result AS diff FROM t;
+ ?column? | bc_result | log | diff
+-----------+--------------------------------------------------------+--------------------------------------------------------+--------------------------------------------------------
+ 1+9.0e-1 | 0.2787536009528290 | 0.2787536009528290 | 0.0000000000000000
+ 1+6.0e-1 | 0.2041199826559248 | 0.2041199826559248 | 0.0000000000000000
+ 1+3.0e-1 | 0.1139433523068368 | 0.1139433523068368 | 0.0000000000000000
+ 1+9.0e-8 | 0.000000039086501612400118 | 0.000000039086501612400118 | 0.000000000000000000000000
+ 1+6.0e-8 | 0.000000026057668132465074 | 0.000000026057668132465074 | 0.000000000000000000000000
+ 1+3.0e-8 | 0.000000013028834261665042 | 0.000000013028834261665042 | 0.000000000000000000000000
+ 1+9.0e-15 | 0.0000000000000039086503371292489 | 0.0000000000000039086503371292489 | 0.0000000000000000000000000000000
+ 1+6.0e-15 | 0.0000000000000026057668914195031 | 0.0000000000000026057668914195031 | 0.0000000000000000000000000000000
+ 1+3.0e-15 | 0.0000000000000013028834457097535 | 0.0000000000000013028834457097535 | 0.0000000000000000000000000000000
+ 1+9.0e-22 | 0.00000000000000000000039086503371292664 | 0.00000000000000000000039086503371292664 | 0.00000000000000000000000000000000000000
+ 1+6.0e-22 | 0.00000000000000000000026057668914195110 | 0.00000000000000000000026057668914195110 | 0.00000000000000000000000000000000000000
+ 1+3.0e-22 | 0.00000000000000000000013028834457097555 | 0.00000000000000000000013028834457097555 | 0.00000000000000000000000000000000000000
+ 1+9.0e-29 | 0.000000000000000000000000000039086503371292664 | 0.000000000000000000000000000039086503371292664 | 0.000000000000000000000000000000000000000000000
+ 1+6.0e-29 | 0.000000000000000000000000000026057668914195110 | 0.000000000000000000000000000026057668914195110 | 0.000000000000000000000000000000000000000000000
+ 1+3.0e-29 | 0.000000000000000000000000000013028834457097555 | 0.000000000000000000000000000013028834457097555 | 0.000000000000000000000000000000000000000000000
+ 1+9.0e-36 | 0.0000000000000000000000000000000000039086503371292664 | 0.0000000000000000000000000000000000039086503371292664 | 0.0000000000000000000000000000000000000000000000000000
+ 1+6.0e-36 | 0.0000000000000000000000000000000000026057668914195110 | 0.0000000000000000000000000000000000026057668914195110 | 0.0000000000000000000000000000000000000000000000000000
+ 1+3.0e-36 | 0.0000000000000000000000000000000000013028834457097555 | 0.0000000000000000000000000000000000013028834457097555 | 0.0000000000000000000000000000000000000000000000000000
+(18 rows)
+
+-- input very large, exact result known
+WITH t(x) AS (SELECT '1e'||n FROM generate_series(1, 100) g(n))
+SELECT x, log(x::numeric) FROM t;
+ x | log
+-------+--------------------
+ 1e1 | 1.0000000000000000
+ 1e2 | 2.0000000000000000
+ 1e3 | 3.0000000000000000
+ 1e4 | 4.0000000000000000
+ 1e5 | 5.000000000000000
+ 1e6 | 6.000000000000000
+ 1e7 | 7.000000000000000
+ 1e8 | 8.000000000000000
+ 1e9 | 9.000000000000000
+ 1e10 | 10.000000000000000
+ 1e11 | 11.000000000000000
+ 1e12 | 12.000000000000000
+ 1e13 | 13.000000000000000
+ 1e14 | 14.000000000000000
+ 1e15 | 15.000000000000000
+ 1e16 | 16.000000000000000
+ 1e17 | 17.000000000000000
+ 1e18 | 18.000000000000000
+ 1e19 | 19.000000000000000
+ 1e20 | 20.000000000000000
+ 1e21 | 21.000000000000000
+ 1e22 | 22.000000000000000
+ 1e23 | 23.000000000000000
+ 1e24 | 24.000000000000000
+ 1e25 | 25.000000000000000
+ 1e26 | 26.000000000000000
+ 1e27 | 27.000000000000000
+ 1e28 | 28.000000000000000
+ 1e29 | 29.000000000000000
+ 1e30 | 30.000000000000000
+ 1e31 | 31.000000000000000
+ 1e32 | 32.000000000000000
+ 1e33 | 33.000000000000000
+ 1e34 | 34.000000000000000
+ 1e35 | 35.000000000000000
+ 1e36 | 36.000000000000000
+ 1e37 | 37.000000000000000
+ 1e38 | 38.000000000000000
+ 1e39 | 39.000000000000000
+ 1e40 | 40.000000000000000
+ 1e41 | 41.000000000000000
+ 1e42 | 42.000000000000000
+ 1e43 | 43.000000000000000
+ 1e44 | 44.00000000000000
+ 1e45 | 45.00000000000000
+ 1e46 | 46.00000000000000
+ 1e47 | 47.00000000000000
+ 1e48 | 48.00000000000000
+ 1e49 | 49.00000000000000
+ 1e50 | 50.00000000000000
+ 1e51 | 51.00000000000000
+ 1e52 | 52.00000000000000
+ 1e53 | 53.00000000000000
+ 1e54 | 54.00000000000000
+ 1e55 | 55.00000000000000
+ 1e56 | 56.00000000000000
+ 1e57 | 57.00000000000000
+ 1e58 | 58.00000000000000
+ 1e59 | 59.00000000000000
+ 1e60 | 60.00000000000000
+ 1e61 | 61.00000000000000
+ 1e62 | 62.00000000000000
+ 1e63 | 63.00000000000000
+ 1e64 | 64.00000000000000
+ 1e65 | 65.00000000000000
+ 1e66 | 66.00000000000000
+ 1e67 | 67.00000000000000
+ 1e68 | 68.00000000000000
+ 1e69 | 69.00000000000000
+ 1e70 | 70.00000000000000
+ 1e71 | 71.00000000000000
+ 1e72 | 72.00000000000000
+ 1e73 | 73.00000000000000
+ 1e74 | 74.00000000000000
+ 1e75 | 75.00000000000000
+ 1e76 | 76.00000000000000
+ 1e77 | 77.00000000000000
+ 1e78 | 78.00000000000000
+ 1e79 | 79.00000000000000
+ 1e80 | 80.00000000000000
+ 1e81 | 81.00000000000000
+ 1e82 | 82.00000000000000
+ 1e83 | 83.00000000000000
+ 1e84 | 84.00000000000000
+ 1e85 | 85.00000000000000
+ 1e86 | 86.00000000000000
+ 1e87 | 87.00000000000000
+ 1e88 | 88.00000000000000
+ 1e89 | 89.00000000000000
+ 1e90 | 90.00000000000000
+ 1e91 | 91.00000000000000
+ 1e92 | 92.00000000000000
+ 1e93 | 93.00000000000000
+ 1e94 | 94.00000000000000
+ 1e95 | 95.00000000000000
+ 1e96 | 96.00000000000000
+ 1e97 | 97.00000000000000
+ 1e98 | 98.00000000000000
+ 1e99 | 99.00000000000000
+ 1e100 | 100.00000000000000
+(100 rows)
+
+-- input very large, non-exact results
+--
+-- bc(1) results computed with a scale of 500 and truncated using the script
+-- below, and then rounded by hand to match the precision of LN():
+--
+-- for p in {10..50..7}
+-- do
+-- for d in {2..9..3}
+-- do
+-- l=$(bc -ql <<< "scale=500 ; l($d*10^$p) / l(10)" | head -n 1)
+-- echo "('${d}.0e$p', $l),"
+-- done
+-- done
+WITH t(x, bc_result) AS (VALUES
+('2.0e10', 10.301029995663981),
+('5.0e10', 10.698970004336019),
+('8.0e10', 10.903089986991944),
+('2.0e17', 17.301029995663981),
+('5.0e17', 17.698970004336019),
+('8.0e17', 17.903089986991944),
+('2.0e24', 24.301029995663981),
+('5.0e24', 24.698970004336019),
+('8.0e24', 24.903089986991944),
+('2.0e31', 31.301029995663981),
+('5.0e31', 31.698970004336019),
+('8.0e31', 31.903089986991944),
+('2.0e38', 38.301029995663981),
+('5.0e38', 38.698970004336019),
+('8.0e38', 38.903089986991944),
+('2.0e45', 45.30102999566398),
+('5.0e45', 45.69897000433602),
+('8.0e45', 45.90308998699194))
+SELECT x, bc_result, log(x::numeric), log(x::numeric)-bc_result AS diff FROM t;
+ x | bc_result | log | diff
+--------+--------------------+--------------------+-------------------
+ 2.0e10 | 10.301029995663981 | 10.301029995663981 | 0.000000000000000
+ 5.0e10 | 10.698970004336019 | 10.698970004336019 | 0.000000000000000
+ 8.0e10 | 10.903089986991944 | 10.903089986991944 | 0.000000000000000
+ 2.0e17 | 17.301029995663981 | 17.301029995663981 | 0.000000000000000
+ 5.0e17 | 17.698970004336019 | 17.698970004336019 | 0.000000000000000
+ 8.0e17 | 17.903089986991944 | 17.903089986991944 | 0.000000000000000
+ 2.0e24 | 24.301029995663981 | 24.301029995663981 | 0.000000000000000
+ 5.0e24 | 24.698970004336019 | 24.698970004336019 | 0.000000000000000
+ 8.0e24 | 24.903089986991944 | 24.903089986991944 | 0.000000000000000
+ 2.0e31 | 31.301029995663981 | 31.301029995663981 | 0.000000000000000
+ 5.0e31 | 31.698970004336019 | 31.698970004336019 | 0.000000000000000
+ 8.0e31 | 31.903089986991944 | 31.903089986991944 | 0.000000000000000
+ 2.0e38 | 38.301029995663981 | 38.301029995663981 | 0.000000000000000
+ 5.0e38 | 38.698970004336019 | 38.698970004336019 | 0.000000000000000
+ 8.0e38 | 38.903089986991944 | 38.903089986991944 | 0.000000000000000
+ 2.0e45 | 45.30102999566398 | 45.30102999566398 | 0.00000000000000
+ 5.0e45 | 45.69897000433602 | 45.69897000433602 | 0.00000000000000
+ 8.0e45 | 45.90308998699194 | 45.90308998699194 | 0.00000000000000
+(18 rows)
+
FROM num_result t1, num_exp_power_10_ln t2
WHERE t1.id1 = t2.id
AND t1.result != t2.expected;
+
+
+--
+-- Test code path for raising to integer powers
+--
+
+-- base less than 1
+--
+-- bc(1) results computed with a scale of 500 and truncated using the script
+-- below, and then rounded by hand to match the precision of POW():
+--
+-- for p in {-20..20}
+-- do
+-- b="0.084738"
+-- r=$(bc -ql <<< "scale=500 ; $b^$p" | head -n 1)
+-- echo "($b, $p, $r),"
+-- done
+
+WITH t(b, p, bc_result) AS (VALUES
+(0.084738, -20, 2744326694304960114888.7859130502035257),
+(0.084738, -19, 232548755422013710215.4459407000481464),
+(0.084738, -18, 19705716436950597776.2364581230406798),
+(0.084738, -17, 1669822999434319754.3627249884302211),
+(0.084738, -16, 141497461326065387.3451885900696001),
+(0.084738, -15, 11990211877848128.7928565907453178),
+(0.084738, -14, 1016026574105094.7376490817865767),
+(0.084738, -13, 86096059836517.5178789078924309),
+(0.084738, -12, 7295607918426.8214300228969888),
+(0.084738, -11, 618215223791.6519943372802450),
+(0.084738, -10, 52386321633.6570066961524534),
+(0.084738, -9, 4439112122.5928274334185666),
+(0.084738, -8, 376161483.0442710110530225),
+(0.084738, -7, 31875171.7502054369346110),
+(0.084738, -6, 2701038.3037689083149651),
+(0.084738, -5, 228880.5837847697527935),
+(0.084738, -4, 19394.8829087538193122),
+(0.084738, -3, 1643.4835879219811409),
+(0.084738, -2, 139.2655122733328379),
+(0.084738, -1, 11.8010809790176780),
+(0.084738, 0, 1),
+(0.084738, 1, .084738),
+(0.084738, 2, .007180528644),
+(0.084738, 3, .0006084636362353),
+(0.084738, 4, .0000515599916073),
+(0.084738, 5, .0000043690905688),
+(0.084738, 6, .0000003702279966),
+(0.084738, 7, .0000000313723800),
+(0.084738, 8, .0000000026584327),
+(0.084738, 9, .0000000002252703),
+(0.084738, 10, .0000000000190890),
+(0.084738, 11, .0000000000016176),
+(0.084738, 12, .0000000000001371),
+(0.084738, 13, .0000000000000116),
+(0.084738, 14, .0000000000000010),
+(0.084738, 15, .0000000000000001),
+(0.084738, 16, .0000000000000000),
+(0.084738, 17, .0000000000000000),
+(0.084738, 18, .0000000000000000),
+(0.084738, 19, .0000000000000000),
+(0.084738, 20, .0000000000000000))
+SELECT b, p, bc_result, b^p AS power, b^p - bc_result AS diff FROM t;
+
+-- base greater than 1
+--
+-- bc(1) results computed with a scale of 500 and truncated using the script
+-- below, and then rounded by hand to match the precision of POW():
+--
+-- for p in {-20..20}
+-- do
+-- b="37.821637"
+-- r=$(bc -ql <<< "scale=500 ; $b^$p" | head -n 1)
+-- echo "($b, $p, $r),"
+-- done
+
+WITH t(b, p, bc_result) AS (VALUES
+(37.821637, -20, .0000000000000000),
+(37.821637, -19, .0000000000000000),
+(37.821637, -18, .0000000000000000),
+(37.821637, -17, .0000000000000000),
+(37.821637, -16, .0000000000000000),
+(37.821637, -15, .0000000000000000),
+(37.821637, -14, .0000000000000000),
+(37.821637, -13, .0000000000000000),
+(37.821637, -12, .0000000000000000),
+(37.821637, -11, .0000000000000000),
+(37.821637, -10, .0000000000000002),
+(37.821637, -9, .0000000000000063),
+(37.821637, -8, .0000000000002388),
+(37.821637, -7, .0000000000090327),
+(37.821637, -6, .0000000003416316),
+(37.821637, -5, .0000000129210673),
+(37.821637, -4, .0000004886959182),
+(37.821637, -3, .0000184832796213),
+(37.821637, -2, .0006990678924066),
+(37.821637, -1, .0264398920649574),
+(37.821637, 0, 1),
+(37.821637, 1, 37.821637),
+(37.821637, 2, 1430.476225359769),
+(37.821637, 3, 54102.9525326873775219),
+(37.821637, 4, 2046262.2313195326271135),
+(37.821637, 5, 77392987.3197773940323425),
+(37.821637, 6, 2927129472.7542235178972258),
+(37.821637, 7, 110708828370.5116321107718772),
+(37.821637, 8, 4187189119324.7924539711577286),
+(37.821637, 9, 158366346921451.9852944363360812),
+(37.821637, 10, 5989674486279224.5007355092228730),
+(37.821637, 11, 226539294168214309.7083246628376531),
+(37.821637, 12, 8568086950266418559.9938312759931069),
+(37.821637, 13, 324059074417413536066.1494087598581043),
+(37.821637, 14, 12256444679171401239980.3109258799733927),
+(37.821637, 15, 463558801566202198479885.2069857662592280),
+(37.821637, 16, 17532552720991931019508170.1002855156233684),
+(37.821637, 17, 663109844696719094948877928.0672523682648687),
+(37.821637, 18, 25079899837245684700124994552.6717306599041850),
+(37.821637, 19, 948562867640665366544581398598.1275771806665398),
+(37.821637, 20, 35876200451584291931921101974730.6901038166532866))
+SELECT b, p, bc_result, b^p AS power, b^p - bc_result AS diff FROM t;
+
+--
+-- Tests for raising to non-integer powers
+--
+
+-- base less than 1
+--
+-- bc(1) results computed with a scale of 500 and truncated using the script
+-- below, and then rounded by hand to match the precision of POW():
+--
+-- for n in {-20..20}
+-- do
+-- b="0.06933247"
+-- p="$n.342987"
+-- r=$(bc -ql <<< "scale=500 ; e($p*l($b))" | head -n 1)
+-- echo "($b, $p, $r),"
+-- done
+
+WITH t(b, p, bc_result) AS (VALUES
+(0.06933247, -20.342987, 379149253615977128356318.39406340),
+(0.06933247, -19.342987, 26287354251852125772450.59436685),
+(0.06933247, -18.342987, 1822567200045909954554.65766042),
+(0.06933247, -17.342987, 126363085720167050546.86216560),
+(0.06933247, -16.342987, 8761064849800910427.02880469),
+(0.06933247, -15.342987, 607426265866876128.15466179),
+(0.06933247, -14.342987, 42114363355427213.14899924),
+(0.06933247, -13.342987, 2919892833909256.59283660),
+(0.06933247, -12.342987, 202443382310228.51544515),
+(0.06933247, -11.342987, 14035899730722.44924025),
+(0.06933247, -10.342987, 973143597003.32229028),
+(0.06933247, -9.342987, 67470449244.92493259),
+(0.06933247, -8.342987, 4677892898.16028054),
+(0.06933247, -7.342987, 324329869.02491071),
+(0.06933247, -6.342987, 22486590.914273551),
+(0.06933247, -5.342987, 1559050.8899661435),
+(0.06933247, -4.342987, 108092.84905705095),
+(0.06933247, -3.342987, 7494.3442144625131),
+(0.06933247, -2.342987, 519.60139541889576),
+(0.06933247, -1.342987, 36.025248159838727),
+(0.06933247, 0.342987, .40036522320023350),
+(0.06933247, 1.342987, .02775830982657349),
+(0.06933247, 2.342987, .001924552183301612),
+(0.06933247, 3.342987, .0001334339565121935),
+(0.06933247, 4.342987, .000009251305786862961),
+(0.06933247, 5.342987, .0000006414158809285026),
+(0.06933247, 6.342987, .00000004447094732199898),
+(0.06933247, 7.342987, .000000003083280621074075),
+(0.06933247, 8.342987, .0000000002137714611621997),
+(0.06933247, 9.342987, .00000000001482130341788437),
+(0.06933247, 10.342987, .000000000001027597574581366),
+(0.06933247, 11.342987, .00000000000007124587801173530),
+(0.06933247, 12.342987, .000000000000004939652699872298),
+(0.06933247, 13.342987, .0000000000000003424783226243151),
+(0.06933247, 14.342987, .00000000000000002374486802900065),
+(0.06933247, 15.342987, .000000000000000001646290350274646),
+(0.06933247, 16.342987, .0000000000000000001141413763217064),
+(0.06933247, 17.342987, .000000000000000000007913703549583420),
+(0.06933247, 18.342987, .0000000000000000000005486766139403860),
+(0.06933247, 19.342987, .00000000000000000000003804110487572339),
+(0.06933247, 20.342987, .000000000000000000000002637483762562946))
+SELECT b, p, bc_result, b^p AS power, b^p - bc_result AS diff FROM t;
+
+-- base greater than 1
+--
+-- bc(1) results computed with a scale of 500 and truncated using the script
+-- below, and then rounded by hand to match the precision of POW():
+--
+-- for n in {-20..20}
+-- do
+-- b="27.234987"
+-- p="$n.230957"
+-- r=$(bc -ql <<< "scale=500 ; e($p*l($b))" | head -n 1)
+-- echo "($b, $p, $r),"
+-- done
+
+WITH t(b, p, bc_result) AS (VALUES
+(27.234987, -20.230957, .000000000000000000000000000009247064512095633),
+(27.234987, -19.230957, .0000000000000000000000000002518436817750859),
+(27.234987, -18.230957, .000000000000000000000000006858959399176602),
+(27.234987, -17.230957, .0000000000000000000000001868036700701026),
+(27.234987, -16.230957, .000000000000000000000005087595525911532),
+(27.234987, -15.230957, .0000000000000000000001385605980094587),
+(27.234987, -14.230957, .000000000000000000003773696085499835),
+(27.234987, -13.230957, .0000000000000000001027765638305389),
+(27.234987, -12.230957, .000000000000000002799118379829397),
+(27.234987, -11.230957, .00000000000000007623395268611469),
+(27.234987, -10.230957, .000000000000002076230710364949),
+(27.234987, -9.230957, .00000000000005654611640579014),
+(27.234987, -8.230957, .000000000001540032745212181),
+(27.234987, -7.230957, .00000000004194277179542807),
+(27.234987, -6.230957, .000000001142310844592450),
+(27.234987, -5.230957, .00000003111082100243440),
+(27.234987, -4.230957, .0000008473028055606278),
+(27.234987, -3.230957, .00002307628089450723),
+(27.234987, -2.230957, .0006284822101702527),
+(27.234987, -1.230957, .01711670482371810),
+(27.234987, 0.230957, 2.1451253063142300),
+(27.234987, 1.230957, 58.422459830839071),
+(27.234987, 2.230957, 1591.1349340009243),
+(27.234987, 3.230957, 43334.539242761031),
+(27.234987, 4.230957, 1180215.6129275865),
+(27.234987, 5.230957, 32143156.875279851),
+(27.234987, 6.230957, 875418459.63720737),
+(27.234987, 7.230957, 23842010367.779367),
+(27.234987, 8.230957, 649336842420.336290),
+(27.234987, 9.230957, 17684680461938.907402),
+(27.234987, 10.230957, 481642042480060.137900),
+(27.234987, 11.230957, 13117514765597885.614921),
+(27.234987, 12.230957, 357255344113366461.949871),
+(27.234987, 13.230957, 9729844652608062117.440722),
+(27.234987, 14.230957, 264992192625800087863.690528),
+(27.234987, 15.230957, 7217058921265161257566.469315),
+(27.234987, 16.230957, 196556505898890690402726.443417),
+(27.234987, 17.230957, 5353213882921711267539279.451015),
+(27.234987, 18.230957, 145794710509592328389185797.837767),
+(27.234987, 19.230957, 3970717045397510438979206144.696206),
+(27.234987, 20.230957, 108142427112079606637962972621.121293))
+SELECT b, p, bc_result, b^p AS power, b^p - bc_result AS diff FROM t;
+
+--
+-- Tests for EXP()
+--
+
+-- bc(1) results computed with a scale of 500 and truncated using the script
+-- below, and then rounded by hand to match the precision of EXP():
+--
+-- for n in {-20..20}
+-- do
+-- x="$n.29837"
+-- r=$(bc -ql <<< "scale=500 ; e($x)" | head -n 1)
+-- echo "($x, $r),"
+-- done
+
+WITH t(x, bc_result) AS (VALUES
+(-20.29837, .000000001529431101152222),
+(-19.29837, .000000004157424770142192),
+(-18.29837, .00000001130105220586304),
+(-17.29837, .00000003071944485366452),
+(-16.29837, .00000008350410872606600),
+(-15.29837, .0000002269877013517336),
+(-14.29837, .0000006170165438681061),
+(-13.29837, .000001677224859055276),
+(-12.29837, .000004559169856609741),
+(-11.29837, .00001239310857408049),
+(-10.29837, .00003368796183504298),
+(-9.29837, .00009157337449401917),
+(-8.29837, .0002489222398577673),
+(-7.29837, .0006766408013046928),
+(-6.29837, .001839300394580514),
+(-5.29837, .004999736839665763),
+(-4.29837, .01359069379834070),
+(-3.29837, .03694333598818056),
+(-2.29837, .1004223988993283),
+(-1.29837, .2729763820983097),
+(0.29837, 1.3476603299656679),
+(1.29837, 3.6633205858807959),
+(2.29837, 9.9579377804197108),
+(3.29837, 27.068481317440698),
+(4.29837, 73.579760889182206),
+(5.29837, 200.01052696742555),
+(6.29837, 543.68498095607070),
+(7.29837, 1477.8890041389891),
+(8.29837, 4017.3188244304487),
+(9.29837, 10920.204759575742),
+(10.29837, 29684.194161006717),
+(11.29837, 80690.005580314652),
+(12.29837, 219338.17590722828),
+(13.29837, 596222.97785597218),
+(14.29837, 1620702.0864156289),
+(15.29837, 4405525.0308492653),
+(16.29837, 11975458.636179032),
+(17.29837, 32552671.598188404),
+(18.29837, 88487335.673150406),
+(19.29837, 240533516.60908059),
+(20.29837, 653837887.33381570))
+SELECT x, bc_result, exp(x), exp(x)-bc_result AS diff FROM t;
+
+--
+-- Tests for LN()
+--
+
+-- input very small
+--
+-- bc(1) results computed with a scale of 500 and truncated using the script
+-- below, and then rounded by hand to match the precision of LN():
+--
+-- for p in {1..40}
+-- do
+-- l=$(bc -ql <<< "scale=500 ; l(10^-$p)" | head -n 1)
+-- echo "('1.0e-$p', $l),"
+-- done
+
+WITH t(x, bc_result) AS (VALUES
+('1.0e-1', -2.3025850929940457),
+('1.0e-2', -4.6051701859880914),
+('1.0e-3', -6.9077552789821371),
+('1.0e-4', -9.2103403719761827),
+('1.0e-5', -11.512925464970228),
+('1.0e-6', -13.815510557964274),
+('1.0e-7', -16.118095650958320),
+('1.0e-8', -18.420680743952365),
+('1.0e-9', -20.723265836946411),
+('1.0e-10', -23.025850929940457),
+('1.0e-11', -25.328436022934503),
+('1.0e-12', -27.631021115928548),
+('1.0e-13', -29.933606208922594),
+('1.0e-14', -32.236191301916640),
+('1.0e-15', -34.5387763949106853),
+('1.0e-16', -36.84136148790473094),
+('1.0e-17', -39.143946580898776628),
+('1.0e-18', -41.4465316738928223123),
+('1.0e-19', -43.74911676688686799634),
+('1.0e-20', -46.051701859880913680360),
+('1.0e-21', -48.3542869528749593643778),
+('1.0e-22', -50.65687204586900504839581),
+('1.0e-23', -52.959457138863050732413803),
+('1.0e-24', -55.2620422318570964164317949),
+('1.0e-25', -57.56462732485114210044978637),
+('1.0e-26', -59.867212417845187784467777822),
+('1.0e-27', -62.1697975108392334684857692765),
+('1.0e-28', -64.47238260383327915250376073116),
+('1.0e-29', -66.774967696827324836521752185847),
+('1.0e-30', -69.0775527898213705205397436405309),
+('1.0e-31', -71.38013788281541620455773509521529),
+('1.0e-32', -73.682722975809461888575726549899655),
+('1.0e-33', -75.9853080688035075725937180045840189),
+('1.0e-34', -78.28789316179755325661170945926838306),
+('1.0e-35', -80.590478254791598940629700913952747266),
+('1.0e-36', -82.8930633477856446246476923686371114736),
+('1.0e-37', -85.19564844077969030866568382332147568124),
+('1.0e-38', -87.498233533773735992683675278005839888842),
+('1.0e-39', -89.8008186267677816767016667326902040964430),
+('1.0e-40', -92.10340371976182736071965818737456830404406))
+SELECT x, bc_result, ln(x::numeric), ln(x::numeric)-bc_result AS diff FROM t;
+
+-- input very close to but smaller than 1
+--
+-- bc(1) results computed with a scale of 500 and truncated using the script
+-- below, and then rounded by hand to match the precision of LN():
+--
+-- for p in {1..40}
+-- do
+-- l=$(bc -ql <<< "scale=500 ; l(1-10^-$p)" | head -n 1)
+-- echo "('1.0e-$p', $l),"
+-- done
+
+WITH t(x, bc_result) AS (VALUES
+('1.0e-1', -.10536051565782630),
+('1.0e-2', -.010050335853501441),
+('1.0e-3', -.0010005003335835335),
+('1.0e-4', -.00010000500033335834),
+('1.0e-5', -.000010000050000333336),
+('1.0e-6', -.0000010000005000003333),
+('1.0e-7', -.00000010000000500000033),
+('1.0e-8', -.000000010000000050000000),
+('1.0e-9', -.0000000010000000005000000),
+('1.0e-10', -.00000000010000000000500000),
+('1.0e-11', -.000000000010000000000050000),
+('1.0e-12', -.0000000000010000000000005000),
+('1.0e-13', -.00000000000010000000000000500),
+('1.0e-14', -.000000000000010000000000000050),
+('1.0e-15', -.0000000000000010000000000000005),
+('1.0e-16', -.00000000000000010000000000000001),
+('1.0e-17', -.000000000000000010000000000000000),
+('1.0e-18', -.0000000000000000010000000000000000),
+('1.0e-19', -.00000000000000000010000000000000000),
+('1.0e-20', -.000000000000000000010000000000000000),
+('1.0e-21', -.0000000000000000000010000000000000000),
+('1.0e-22', -.00000000000000000000010000000000000000),
+('1.0e-23', -.000000000000000000000010000000000000000),
+('1.0e-24', -.0000000000000000000000010000000000000000),
+('1.0e-25', -.00000000000000000000000010000000000000000),
+('1.0e-26', -.000000000000000000000000010000000000000000),
+('1.0e-27', -.0000000000000000000000000010000000000000000),
+('1.0e-28', -.00000000000000000000000000010000000000000000),
+('1.0e-29', -.000000000000000000000000000010000000000000000),
+('1.0e-30', -.0000000000000000000000000000010000000000000000),
+('1.0e-31', -.00000000000000000000000000000010000000000000000),
+('1.0e-32', -.000000000000000000000000000000010000000000000000),
+('1.0e-33', -.0000000000000000000000000000000010000000000000000),
+('1.0e-34', -.00000000000000000000000000000000010000000000000000),
+('1.0e-35', -.000000000000000000000000000000000010000000000000000),
+('1.0e-36', -.0000000000000000000000000000000000010000000000000000),
+('1.0e-37', -.00000000000000000000000000000000000010000000000000000),
+('1.0e-38', -.000000000000000000000000000000000000010000000000000000),
+('1.0e-39', -.0000000000000000000000000000000000000010000000000000000),
+('1.0e-40', -.00000000000000000000000000000000000000010000000000000000))
+SELECT '1-'||x, bc_result, ln(1.0-x::numeric), ln(1.0-x::numeric)-bc_result AS diff FROM t;
+
+-- input very close to but larger than 1
+--
+-- bc(1) results computed with a scale of 500 and truncated using the script
+-- below, and then rounded by hand to match the precision of LN():
+--
+-- for p in {1..40}
+-- do
+-- l=$(bc -ql <<< "scale=500 ; l(1+10^-$p)" | head -n 1)
+-- echo "('1.0e-$p', $l),"
+-- done
+
+WITH t(x, bc_result) AS (VALUES
+('1.0e-1', .09531017980432486),
+('1.0e-2', .009950330853168083),
+('1.0e-3', .0009995003330835332),
+('1.0e-4', .00009999500033330834),
+('1.0e-5', .000009999950000333331),
+('1.0e-6', .0000009999995000003333),
+('1.0e-7', .00000009999999500000033),
+('1.0e-8', .000000009999999950000000),
+('1.0e-9', .0000000009999999995000000),
+('1.0e-10', .00000000009999999999500000),
+('1.0e-11', .000000000009999999999950000),
+('1.0e-12', .0000000000009999999999995000),
+('1.0e-13', .00000000000009999999999999500),
+('1.0e-14', .000000000000009999999999999950),
+('1.0e-15', .0000000000000009999999999999995),
+('1.0e-16', .00000000000000010000000000000000),
+('1.0e-17', .000000000000000010000000000000000),
+('1.0e-18', .0000000000000000010000000000000000),
+('1.0e-19', .00000000000000000010000000000000000),
+('1.0e-20', .000000000000000000010000000000000000),
+('1.0e-21', .0000000000000000000010000000000000000),
+('1.0e-22', .00000000000000000000010000000000000000),
+('1.0e-23', .000000000000000000000010000000000000000),
+('1.0e-24', .0000000000000000000000010000000000000000),
+('1.0e-25', .00000000000000000000000010000000000000000),
+('1.0e-26', .000000000000000000000000010000000000000000),
+('1.0e-27', .0000000000000000000000000010000000000000000),
+('1.0e-28', .00000000000000000000000000010000000000000000),
+('1.0e-29', .000000000000000000000000000010000000000000000),
+('1.0e-30', .0000000000000000000000000000010000000000000000),
+('1.0e-31', .00000000000000000000000000000010000000000000000),
+('1.0e-32', .000000000000000000000000000000010000000000000000),
+('1.0e-33', .0000000000000000000000000000000010000000000000000),
+('1.0e-34', .00000000000000000000000000000000010000000000000000),
+('1.0e-35', .000000000000000000000000000000000010000000000000000),
+('1.0e-36', .0000000000000000000000000000000000010000000000000000),
+('1.0e-37', .00000000000000000000000000000000000010000000000000000),
+('1.0e-38', .000000000000000000000000000000000000010000000000000000),
+('1.0e-39', .0000000000000000000000000000000000000010000000000000000),
+('1.0e-40', .00000000000000000000000000000000000000010000000000000000))
+SELECT '1+'||x, bc_result, ln(1.0+x::numeric), ln(1.0+x::numeric)-bc_result AS diff FROM t;
+
+-- input very large
+--
+-- bc(1) results computed with a scale of 500 and truncated using the script
+-- below, and then rounded by hand to match the precision of LN():
+--
+-- for p in {1..40}
+-- do
+-- l=$(bc -ql <<< "scale=500 ; l(10^$p)" | head -n 1)
+-- echo "('1.0e$p', $l),"
+-- done
+
+WITH t(x, bc_result) AS (VALUES
+('1.0e1', 2.3025850929940457),
+('1.0e2', 4.6051701859880914),
+('1.0e3', 6.9077552789821371),
+('1.0e4', 9.2103403719761827),
+('1.0e5', 11.512925464970228),
+('1.0e6', 13.815510557964274),
+('1.0e7', 16.118095650958320),
+('1.0e8', 18.420680743952365),
+('1.0e9', 20.723265836946411),
+('1.0e10', 23.025850929940457),
+('1.0e11', 25.328436022934503),
+('1.0e12', 27.631021115928548),
+('1.0e13', 29.933606208922594),
+('1.0e14', 32.236191301916640),
+('1.0e15', 34.538776394910685),
+('1.0e16', 36.841361487904731),
+('1.0e17', 39.143946580898777),
+('1.0e18', 41.446531673892822),
+('1.0e19', 43.749116766886868),
+('1.0e20', 46.051701859880914),
+('1.0e21', 48.354286952874959),
+('1.0e22', 50.656872045869005),
+('1.0e23', 52.959457138863051),
+('1.0e24', 55.262042231857096),
+('1.0e25', 57.564627324851142),
+('1.0e26', 59.867212417845188),
+('1.0e27', 62.169797510839233),
+('1.0e28', 64.472382603833279),
+('1.0e29', 66.774967696827325),
+('1.0e30', 69.077552789821371),
+('1.0e31', 71.380137882815416),
+('1.0e32', 73.682722975809462),
+('1.0e33', 75.985308068803508),
+('1.0e34', 78.287893161797553),
+('1.0e35', 80.590478254791599),
+('1.0e36', 82.893063347785645),
+('1.0e37', 85.195648440779690),
+('1.0e38', 87.498233533773736),
+('1.0e39', 89.800818626767782),
+('1.0e40', 92.103403719761827))
+SELECT x, bc_result, ln(x::numeric), ln(x::numeric)-bc_result AS diff FROM t;
+
+-- input huge
+--
+-- bc(1) results computed with a scale of 1000 and truncated using the script
+-- below, and then rounded by hand to match the precision of LN():
+--
+-- for p in {1..10}
+-- do
+-- l=$(bc -ql <<< "scale=1000 ; l(10^${p}00)" | head -n 1)
+-- echo "('1.0e${p}00', $l),"
+-- done
+
+WITH t(x, bc_result) AS (VALUES
+('1.0e100', 230.25850929940457),
+('1.0e200', 460.51701859880914),
+('1.0e300', 690.77552789821371),
+('1.0e400', 921.03403719761827),
+('1.0e500', 1151.2925464970228),
+('1.0e600', 1381.5510557964274),
+('1.0e700', 1611.8095650958320),
+('1.0e800', 1842.0680743952365),
+('1.0e900', 2072.3265836946411),
+('1.0e1000', 2302.5850929940457))
+SELECT x, bc_result, ln(x::numeric), ln(x::numeric)-bc_result AS diff FROM t;
+
+--
+-- Tests for LOG() (base 10)
+--
+
+-- input very small, exact result known
+WITH t(x) AS (SELECT '1e-'||n FROM generate_series(1, 100) g(n))
+SELECT x, log(x::numeric) FROM t;
+
+-- input very small, non-exact results
+--
+-- bc(1) results computed with a scale of 500 and truncated using the script
+-- below, and then rounded by hand to match the precision of LN():
+--
+-- for p in {1..50..7}
+-- do
+-- for d in {9..1..3}
+-- do
+-- l=$(bc -ql <<< "scale=500 ; l($d*10^-$p) / l(10)" | head -n 1)
+-- echo "('${d}.0e-$p', $l),"
+-- done
+-- done
+
+WITH t(x, bc_result) AS (VALUES
+('9.0e-1', -.04575749056067513),
+('6.0e-1', -.2218487496163564),
+('3.0e-1', -.5228787452803376),
+('9.0e-8', -7.045757490560675),
+('6.0e-8', -7.221848749616356),
+('3.0e-8', -7.522878745280338),
+('9.0e-15', -14.0457574905606751),
+('6.0e-15', -14.2218487496163564),
+('3.0e-15', -14.5228787452803376),
+('9.0e-22', -21.04575749056067512540994),
+('6.0e-22', -21.22184874961635636749123),
+('3.0e-22', -21.52287874528033756270497),
+('9.0e-29', -28.045757490560675125409944193490),
+('6.0e-29', -28.221848749616356367491233202020),
+('3.0e-29', -28.522878745280337562704972096745),
+('9.0e-36', -35.0457574905606751254099441934897693816),
+('6.0e-36', -35.2218487496163563674912332020203916640),
+('3.0e-36', -35.5228787452803375627049720967448846908),
+('9.0e-43', -42.04575749056067512540994419348976938159974227),
+('6.0e-43', -42.22184874961635636749123320202039166403168125),
+('3.0e-43', -42.52287874528033756270497209674488469079987114),
+('9.0e-50', -49.045757490560675125409944193489769381599742271618608),
+('6.0e-50', -49.221848749616356367491233202020391664031681254347196),
+('3.0e-50', -49.522878745280337562704972096744884690799871135809304))
+SELECT x, bc_result, log(x::numeric), log(x::numeric)-bc_result AS diff FROM t;
+
+-- input very close to but smaller than 1
+--
+-- bc(1) results computed with a scale of 500 and truncated using the script
+-- below, and then rounded by hand to match the precision of LN():
+--
+-- for p in {1..40..7}
+-- do
+-- for d in {9..1..3}
+-- do
+-- l=$(bc -ql <<< "scale=500 ; l(1-$d*10^-$p) / l(10)" | head -n 1)
+-- echo "('${d}.0e-$p', $l),"
+-- done
+-- done
+
+WITH t(x, bc_result) AS (VALUES
+('9.0e-1', -1.0000000000000000),
+('6.0e-1', -.3979400086720376),
+('3.0e-1', -.1549019599857432),
+('9.0e-8', -.000000039086505130185422),
+('6.0e-8', -.000000026057669695925208),
+('3.0e-8', -.000000013028834652530076),
+('9.0e-15', -.0000000000000039086503371292840),
+('6.0e-15', -.0000000000000026057668914195188),
+('3.0e-15', -.0000000000000013028834457097574),
+('9.0e-22', -.00000000000000000000039086503371292664),
+('6.0e-22', -.00000000000000000000026057668914195110),
+('3.0e-22', -.00000000000000000000013028834457097555),
+('9.0e-29', -.000000000000000000000000000039086503371292664),
+('6.0e-29', -.000000000000000000000000000026057668914195110),
+('3.0e-29', -.000000000000000000000000000013028834457097555),
+('9.0e-36', -.0000000000000000000000000000000000039086503371292664),
+('6.0e-36', -.0000000000000000000000000000000000026057668914195110),
+('3.0e-36', -.0000000000000000000000000000000000013028834457097555))
+SELECT '1-'||x, bc_result, log(1.0-x::numeric), log(1.0-x::numeric)-bc_result AS diff FROM t;
+
+-- input very close to but larger than 1
+--
+-- bc(1) results computed with a scale of 500 and truncated using the script
+-- below, and then rounded by hand to match the precision of LN():
+--
+-- for p in {1..40..7}
+-- do
+-- for d in {9..1..3}
+-- do
+-- l=$(bc -ql <<< "scale=500 ; l(1+$d*10^-$p) / l(10)" | head -n 1)
+-- echo "('${d}.0e-$p', $l),"
+-- done
+-- done
+
+WITH t(x, bc_result) AS (VALUES
+('9.0e-1', .2787536009528290),
+('6.0e-1', .2041199826559248),
+('3.0e-1', .1139433523068368),
+('9.0e-8', .000000039086501612400118),
+('6.0e-8', .000000026057668132465074),
+('3.0e-8', .000000013028834261665042),
+('9.0e-15', .0000000000000039086503371292489),
+('6.0e-15', .0000000000000026057668914195031),
+('3.0e-15', .0000000000000013028834457097535),
+('9.0e-22', .00000000000000000000039086503371292664),
+('6.0e-22', .00000000000000000000026057668914195110),
+('3.0e-22', .00000000000000000000013028834457097555),
+('9.0e-29', .000000000000000000000000000039086503371292664),
+('6.0e-29', .000000000000000000000000000026057668914195110),
+('3.0e-29', .000000000000000000000000000013028834457097555),
+('9.0e-36', .0000000000000000000000000000000000039086503371292664),
+('6.0e-36', .0000000000000000000000000000000000026057668914195110),
+('3.0e-36', .0000000000000000000000000000000000013028834457097555))
+SELECT '1+'||x, bc_result, log(1.0+x::numeric), log(1.0+x::numeric)-bc_result AS diff FROM t;
+
+-- input very large, exact result known
+WITH t(x) AS (SELECT '1e'||n FROM generate_series(1, 100) g(n))
+SELECT x, log(x::numeric) FROM t;
+
+-- input very large, non-exact results
+--
+-- bc(1) results computed with a scale of 500 and truncated using the script
+-- below, and then rounded by hand to match the precision of LN():
+--
+-- for p in {10..50..7}
+-- do
+-- for d in {2..9..3}
+-- do
+-- l=$(bc -ql <<< "scale=500 ; l($d*10^$p) / l(10)" | head -n 1)
+-- echo "('${d}.0e$p', $l),"
+-- done
+-- done
+
+WITH t(x, bc_result) AS (VALUES
+('2.0e10', 10.301029995663981),
+('5.0e10', 10.698970004336019),
+('8.0e10', 10.903089986991944),
+('2.0e17', 17.301029995663981),
+('5.0e17', 17.698970004336019),
+('8.0e17', 17.903089986991944),
+('2.0e24', 24.301029995663981),
+('5.0e24', 24.698970004336019),
+('8.0e24', 24.903089986991944),
+('2.0e31', 31.301029995663981),
+('5.0e31', 31.698970004336019),
+('8.0e31', 31.903089986991944),
+('2.0e38', 38.301029995663981),
+('5.0e38', 38.698970004336019),
+('8.0e38', 38.903089986991944),
+('2.0e45', 45.30102999566398),
+('5.0e45', 45.69897000433602),
+('8.0e45', 45.90308998699194))
+SELECT x, bc_result, log(x::numeric), log(x::numeric)-bc_result AS diff FROM t;
projects / postgresql / commitdiff