Bug #63136 [Opn]: pow() returns NaN where base is negative and exponent is an odd number root

Edit report at https://bugs.php.net/bug.php?id=63136&edit=1 ID: 63136 User updated by: tstobbe at sacbee dot com Reported by: tstobbe at sacbee dot com Summary: pow() returns NaN where base is negative and exponent is an odd number root Status: Open Type: Bug Package: Math related Operating System: Linux (fc17, 32-bit) PHP Version: 5.4.7 Block user comment: N Private report: N New Comment: It should be noted that all subsequent fractional pow() issues are related to this. For example: pow(-[any number], 1/5) vs pow(-[any number], 2/5). Likewise I suspect that most other exponent based functions (such as log with an arbitrary base) are probably suspect, but this hasn't been verified. Previous Comments: ------------------------------------------------------------------------ [2012-09-21 22:38:15] tstobbe at sacbee dot com Description: ------------ Odd roots (3, 5, etc) of negative numbers passed to pow() result in NaN rather than the actual result. While this makes sense for even numbered roots (sqrt and what-not), it wrecks havoc on any system that actually uses arbitrary roots of negative numbers. Example: -2*-2*-2 = -8; pow(-8, 1/3) should return -2 Test script: --------------- var_dump(pow(-8, 1/3)); Expected result: ---------------- float(-2) Actual result: -------------- float(NAN) ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=63136&edit=1