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- New pow() function. It now gives warnings on wrong input, and

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returns integer result when possible
@- New pow() implementation, which returns an integer when possible,
@  and warnings on wrong input (jeroen)
This commit is contained in:
Jeroen van Wolffelaar 2001-08-03 22:19:11 +00:00
parent c2150f7038
commit 7733d95770
1 changed files with 101 additions and 7 deletions
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108
ext/standard/math.c
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@ -377,19 +377,113 @@ PHP_FUNCTION(pi)
}
/* }}} */
/* {{{ proto double pow(double base, double exponent)
Returns base raised to the power of exponent */
/* {{{ proto number pow(number lbase, number lexponent)
Returns lbase raised to the power of lexponent. Returns
integer result when possible. */
PHP_FUNCTION(pow)
{
zval **num1, **num2;
/* FIXME: What is our policy on float-overflow? With pow, it's
* extremely easy to request results that won't fit in any double.
*/
if (ZEND_NUM_ARGS() != 2 || zend_get_parameters_ex(2,&num1,&num2) == FAILURE) {
zval **zbase, **zexp;
long lbase,lexp;
double dval,dbase,pos_result;
long result = 1;
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 */
dbase = Z_TYPE_PP(zbase) == IS_LONG ? (double) Z_LVAL_PP(zbase)
: Z_DVAL_PP(zbase);
if ( dbase <= 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;
}
RETURN_DOUBLE(exp(log(dbase) * Z_DVAL_PP(zexp)));
}
/* 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 */
pos_result = exp(log(-Z_DVAL_PP(zbase)) * (double)lexp);
RETURN_DOUBLE(lexp & 1 ? -pos_result : pos_result);
}
}
/* pow(int,int) */
if (lexp == 0) {
RETURN_LONG(1);
}
lbase = Z_LVAL_PP(zbase);
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((double) (lbase>0?lbase:-lbase)) *
(double) lexp);
/* long result = 1; */
if (lexp < 0 || dval > (double) LONG_MAX) {
/* 1/n ( abs(n) > 1 ) || overflow */
RETURN_DOUBLE(((lexp & 1) && lbase<0) ? -dval : dval);
}
/* loop runs at most log(log(LONG_MAX)) times, i.e. ~ 5 */
while (lexp > 0) {
if (lexp & 1) /* odd */
result *= lbase;
lexp >>= 1;
lbase *= lbase;
}
RETURN_LONG(result);
}
convert_to_double_ex(num1);
convert_to_double_ex(num2);
RETURN_DOUBLE(pow((*num1)->value.dval, (*num2)->value.dval));
}
/* }}} */