ID: 15811
Updated by: [EMAIL PROTECTED]
Reported By: [EMAIL PROTECTED]
Status: Closed
Bug Type: *Math Functions
Operating System: linux redhat
PHP Version: 4.1.2
New Comment:
this function was rewritten completely in the 4.2/HEAD branch. (it's
now about eight times shorter, and actually correct.)
Previous Comments:
------------------------------------------------------------------------
[2002-03-01 14:28:50] [EMAIL PROTECTED]
i looked little bit to your function pow (in math.c) and added some
comments make sure you fixed it also for exponent type double.
PHP_FUNCTION(pow)
{
/* FIXME: What is our policy on float-overflow? With pow, it's
* extremely easy to request results that won't fit in any double.
*/
zval **zbase, **zexp;
long lbase, lexp;
double dval;
if (ZEND_NUM_ARGS() != 2) {
WRONG_PARAM_COUNT;
}
zend_get_parameters_ex(ZEND_NUM_ARGS(), &zbase, &zexp);
convert_scalar_to_number_ex(zbase);
convert_scalar_to_number_ex(zexp);
if ((Z_TYPE_PP(zbase) != IS_LONG && Z_TYPE_PP(zbase) != IS_DOUBLE) ||
(Z_TYPE_PP(zexp ) != IS_LONG && Z_TYPE_PP(zexp ) != IS_DOUBLE)) {
php_error(E_WARNING, "Invalid argument(s) passed to pow()");
RETURN_FALSE;
}
if (Z_TYPE_PP(zexp) == IS_DOUBLE) {
/* pow(?, float), this is the ^^ case */
convert_to_double_ex(zbase);
if (Z_DVAL_PP(zbase) < 0.0) {
/* Note that with the old behaviour, php pow() returned bogus
results. Try pow(-1, 2.5) in PHP <= 4.0.6 ... */
php_error(E_WARNING, "Trying to raise a nonpositive value to a
broken power");
RETURN_FALSE;
}
/* !!!!!!!!!!!!!!!!!!!! Here you are missing part of the code */
RETURN_DOUBLE(exp(log(Z_DVAL_PP(zbase)) * Z_DVAL_PP(zexp)));
/* !!!!!!!!!!!!!!!!!!!! It should look like */
if (Z_DVAL_PP(zbase) == 0.0) {
if (lexp < 0) {
php_error(E_WARNING,
"Division by zero: pow(0.0, [negative
integer])");
RETURN_FALSE;
} else {
RETURN_DOUBLE(0.0);
}
} else {
RETURN_DOUBLE(exp(log(Z_DVAL_PP(zbase)) *
Z_DVAL_PP(zexp)));
}
}
/* !!!!!!!!!!!!!!!!!!!! This is an end, please look at the end */
/* pow(?, int), this is the ** case */
lexp = Z_LVAL_PP(zexp);
if (Z_TYPE_PP(zbase) == IS_DOUBLE) {
/* pow(float, int) */
if (lexp == 0) {
RETURN_DOUBLE(1.0);
}
if (Z_DVAL_PP(zbase) > 0.0) {
RETURN_DOUBLE(exp(log(Z_DVAL_PP(zbase)) * lexp));
} else if (Z_DVAL_PP(zbase) == 0.0) {
if (lexp < 0) {
php_error(E_WARNING,
"Division by zero: pow(0.0, [negative
integer])");
RETURN_FALSE;
} else {
RETURN_DOUBLE(0.0);
}
} else { /* lbase < 0.0 */
dval = exp(log(-Z_DVAL_PP(zbase)) * (double)lexp);
RETURN_DOUBLE(lexp & 1 ? -dval : dval);
}
}
/* pow(int, int) */
if (lexp == 0) {
RETURN_LONG(1);
}
lbase = Z_LVAL_PP(zbase);
/* lexp != 0 */
switch (lbase) {
case -1:
RETURN_LONG( lexp & 1 ? -1 : 1 ); /* if lexp=odd ... */
case 0:
if (lexp < 0) {
php_error(E_WARNING,
"Division by zero: pow(0, [negative
integer])");
RETURN_FALSE;
} else {
RETURN_LONG(0);
}
case 1:
RETURN_LONG(1);
default:
/* abs(lbase) > 1 */
dval = exp(log(lbase>0? (double)lbase : -(double)lbase ) *
(double) lexp);
if (lexp < 0 || dval > (double) LONG_MAX) {
/* 1/n ( abs(n) > 1 ) || overflow */
RETURN_DOUBLE(((lexp & 1) && lbase<0) ? -dval : dval);
}
Z_TYPE_P(return_value) = IS_LONG;
Z_LVAL_P(return_value) = 1;
/* loop runs at most log(log(LONG_MAX)) times, i.e. ~ 5 */
while (lexp > 0) {
if (lexp & 1) /* odd */
Z_LVAL_P(return_value) *= lbase;
lexp >>= 1;
lbase *= lbase;
}
/* !!!!!!!!!!!!!!!!!!!! This is nice that you want to return integer
when possible,
but this is probably the slowest algorithm you could use */
/* return */
}
}
------------------------------------------------------------------------
[2002-03-01 10:25:19] [EMAIL PROTECTED]
It's fixed for 4.2.0 already:
[derick@kossu dev]$ php
<?php
echo pow (0, 80);
?>
X-Powered-By: PHP/4.2.0-dev
Content-type: text/html
0
Derick
------------------------------------------------------------------------
[2002-03-01 10:23:27] [EMAIL PROTECTED]
function pow()
in version 4.0.6 function pow(0,x),x!=0 always returns 0.
in version 4.1.2 function pow(0,x) x!=0 always returns nan, i think
that is not correct.
------------------------------------------------------------------------
--
Edit this bug report at http://bugs.php.net/?id=15811&edit=1
