From 4a586bd405c2c4905a0a6964275ecfdc324f0e8e Mon Sep 17 00:00:00 2001
From: Bruce Momjian <bruce@momjian.us>
Date: Thu, 8 May 2008 22:17:54 +0000
Subject: [PATCH] Add regression test for various power expressions with a zero
base, and adjust source code to be more modular.
---
src/backend/utils/adt/numeric.c | 33 ++++++++++++++--------------
src/test/regress/expected/float8.out | 6 +++++
src/test/regress/sql/float8.sql | 2 ++
3 files changed, 25 insertions(+), 16 deletions(-)
diff --git a/src/backend/utils/adt/numeric.c b/src/backend/utils/adt/numeric.c
index defdc623cd..a8cd22611d 100644
--- a/src/backend/utils/adt/numeric.c
+++ b/src/backend/utils/adt/numeric.c
@@ -14,7 +14,7 @@
* Copyright (c) 1998-2008, PostgreSQL Global Development Group
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/utils/adt/numeric.c,v 1.111 2008/05/08 19:25:38 momjian Exp $
+ * $PostgreSQL: pgsql/src/backend/utils/adt/numeric.c,v 1.112 2008/05/08 22:17:54 momjian Exp $
*
*-------------------------------------------------------------------------
*/
@@ -5170,21 +5170,6 @@ power_var(NumericVar *base, NumericVar *exp, NumericVar *result)
int local_rscale;
double val;
- /*
- * This avoids log(0) for cases of 0 raised to a non-integer.
- * Also, while 0 ^ 0 can be either 1 or indeterminate (error), we
- * treat it as one because most programming languages do this.
- * http://en.wikipedia.org/wiki/Exponentiation#Zero_to_the_zero_power
- */
- if (cmp_var(base, &const_zero) == 0)
- {
- if (cmp_var(exp, &const_zero) == 0)
- set_var_from_var(&const_one, result);
- else
- set_var_from_var(&const_zero, result);
- return;
- }
-
/* If exp can be represented as an integer, use power_var_int */
if (exp->ndigits == 0 || exp->ndigits <= exp->weight + 1)
{
@@ -5217,6 +5202,17 @@ power_var(NumericVar *base, NumericVar *exp, NumericVar *result)
free_var(&x);
}
+ /*
+ * This avoids log(0) for cases of 0 raised to a non-integer.
+ * 0 ^ 0 handled by power_var_int().
+ */
+ if (cmp_var(base, &const_zero) == 0)
+ {
+ set_var_from_var(&const_zero, result);
+ result->dscale = NUMERIC_MIN_SIG_DIGITS; /* no need to round */
+ return;
+ }
+
init_var(&ln_base);
init_var(&ln_num);
@@ -5284,6 +5280,11 @@ power_var_int(NumericVar *base, int exp, NumericVar *result, int rscale)
switch (exp)
{
case 0:
+ /*
+ * While 0 ^ 0 can be either 1 or indeterminate (error), we
+ * treat it as 1 because most programming languages do this.
+ * http://en.wikipedia.org/wiki/Exponentiation#Zero_to_the_zero_power
+ */
set_var_from_var(&const_one, result);
result->dscale = rscale; /* no need to round */
return;
diff --git a/src/test/regress/expected/float8.out b/src/test/regress/expected/float8.out
index 38d2cbfb41..f81d9b2bac 100644
--- a/src/test/regress/expected/float8.out
+++ b/src/test/regress/expected/float8.out
@@ -349,6 +349,12 @@ SELECT '' AS bad, f.f1 * '1e200' from FLOAT8_TBL f;
ERROR: value out of range: overflow
SELECT '' AS bad, f.f1 ^ '1e200' from FLOAT8_TBL f;
ERROR: value out of range: overflow
+SELECT 0 ^ 0 + 0 ^ 1 + 0 ^ 0.0 + 0 ^ 0.5;
+ ?column?
+----------
+ 2
+(1 row)
+
SELECT '' AS bad, ln(f.f1) from FLOAT8_TBL f where f.f1 = '0.0' ;
ERROR: cannot take logarithm of zero
SELECT '' AS bad, ln(f.f1) from FLOAT8_TBL f where f.f1 < '0.0' ;
diff --git a/src/test/regress/sql/float8.sql b/src/test/regress/sql/float8.sql
index b4dd7be4b3..92b6b0d7b9 100644
--- a/src/test/regress/sql/float8.sql
+++ b/src/test/regress/sql/float8.sql
@@ -129,6 +129,8 @@ SELECT '' AS bad, f.f1 * '1e200' from FLOAT8_TBL f;
SELECT '' AS bad, f.f1 ^ '1e200' from FLOAT8_TBL f;
+SELECT 0 ^ 0 + 0 ^ 1 + 0 ^ 0.0 + 0 ^ 0.5;
+
SELECT '' AS bad, ln(f.f1) from FLOAT8_TBL f where f.f1 = '0.0' ;
SELECT '' AS bad, ln(f.f1) from FLOAT8_TBL f where f.f1 < '0.0' ;
--
2.40.0