From: Jason Greene <jason@php.net>
Date: Mon, 11 Nov 2002 05:21:35 +0000 (+0000)
Subject: Add the ability to take the logarithm of any base by adding a base parameter
X-Git-Tag: php-4.3.0RC1~123
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=84bd2901c4b41b3b4ef9fa730f51e3b30bf6a0e4;p=php

Add the ability to take the logarithm of any base by adding a base parameter
to log()
Added regression tests for the new form
---

diff --git a/ext/standard/math.c b/ext/standard/math.c
index dafaf05788..9be11538c6 100644
--- a/ext/standard/math.c
+++ b/ext/standard/math.c
@@ -520,19 +520,35 @@ PHP_FUNCTION(log1p)
 /* }}} */
 
 #endif
-/* {{{ proto float log(float number)
-   Returns the natural logarithm of the number */
+/* {{{ proto float log(float number, [float base])
+   Returns the natural logarithm of the number, or the base log if base is specified */
 
 PHP_FUNCTION(log)
 {
-	zval **num;
-
-	if (ZEND_NUM_ARGS() != 1 || zend_get_parameters_ex(1, &num) == FAILURE) {
-		WRONG_PARAM_COUNT;
+	zval **num, **base;
+	
+	switch (ZEND_NUM_ARGS()) {
+		case 1:
+			if (zend_get_parameters_ex(1, &num) == FAILURE) {
+				WRONG_PARAM_COUNT;
+			}
+			convert_to_double_ex(num);
+			RETURN_DOUBLE(log(Z_DVAL_PP(num)));
+		case 2:
+			if (zend_get_parameters_ex(2, &num, &base) == FAILURE) {
+				WRONG_PARAM_COUNT;
+			}
+			convert_to_double_ex(num);
+			convert_to_double_ex(base);
+		
+			if (Z_DVAL_PP(base) <= 0.0) {
+				php_error(E_WARNING, "base must be greater than 0", Z_DVAL_PP(base));
+				RETURN_FALSE;
+			}
+			RETURN_DOUBLE(log(Z_DVAL_PP(num)) / log(Z_DVAL_PP(base)));
+		default:
+			WRONG_PARAM_COUNT;
 	}
-	convert_to_double_ex(num);
-	Z_DVAL_P(return_value) = log(Z_DVAL_PP(num));
-	Z_TYPE_P(return_value) = IS_DOUBLE;
 }
 
 /* }}} */
diff --git a/ext/standard/tests/math/log.phpt b/ext/standard/tests/math/log.phpt
index 344c72fa0d..285b19c853 100644
--- a/ext/standard/tests/math/log.phpt
+++ b/ext/standard/tests/math/log.phpt
@@ -5,17 +5,40 @@ log() tests
 --FILE--
 <?php // $Id$
 echo "On failure, please mail result to php-dev@lists.php.net\n";
-for ($x=0, $count=0; $x < 200; $x++) {
+for ($x = 0, $count= 0; $x < 200; $x++) {
     $x2 = (int) exp(log($x));
     // e ^ log(x) should be close in range to x
     if (($x2 < ($x + 2)) && ($x2 > ($x - 2))) { 
         $count++; 
-    }
-    else {
+    } else {
         print "$x : $x2\n";
     }
 }
 print $count . "\n";
+
+// Now test the base form of log
+for ($base = 2; $base < 11; $base++) {
+    for ($x = 0, $count= 0; $x < 50; $x++) {
+        $x2 = (int) pow($base, log($x, $base));
+        // base ^ log(x) should be close in range to x
+        if (($x2 < ($x + 2)) && ($x2 > ($x - 2))) { 
+            $count++; 
+        } else {
+             print "base $base: $x : $x2\n";
+        }
+    }
+    print $count . "\n";
+}
+?>
 --EXPECT--
 On failure, please mail result to php-dev@lists.php.net
 200
+50
+50
+50
+50
+50
+50
+50
+50
+50