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Add the ability to take the logarithm of any base by adding a base parameter

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to log()
Added regression tests for the new form
This commit is contained in:
Jason Greene 2002-11-11 05:21:35 +00:00
parent 9e2a312f2e
commit 84bd2901c4
2 changed files with 51 additions and 12 deletions
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34
ext/standard/math.c
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@ -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;
}
/* }}} */

29
ext/standard/tests/math/log.phpt
View File

@ -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