Bug->Doc #76287 [Opn->Ana]: bcmod returns incorrect values

Edit report at https://bugs.php.net/bug.php?id=76287&edit=1 ID: 76287 Updated by: cmb@php.net Reported by: kacper dot rowinski at gmail dot com Summary: bcmod returns incorrect values -Status: Open +Status: Analyzed -Type: Bug +Type: Documentation Problem Package: BC math related Operating System: Linux debian PHP Version: 7.2.5 -Assigned To: +Assigned To: cmb Block user comment: N Private report: N New Comment: bcmod() doesn't use floor() but rather truncates towards zero, which is also defined this way for POSIX fmod(), so that the result always has the same sign as the dividend. Therefore, this is not a bug, but rather a documentation issue. Previous Comments: ------------------------------------------------------------------------ [2018-04-30 12:36:40] kacper dot rowinski at gmail dot com Prove https://www.wolframalpha.com/input/?i=0.00000000099999+mod+-0.00056 ------------------------------------------------------------------------ [2018-04-30 12:33:45] kacper dot rowinski at gmail dot com Description: ------------ Using bcmod on float return incorrect value Test script: --------------- <?php $leftOperand = '0.00000000099999'; $modulus = '-0.00056'; $scale =14; // incorrect : echo bcmod($leftOperand,$modulus, $scale); // this how it should work // mod(a, b) = a - b * floor(a/b) /* echo bcsub( $leftOperand, bcmul( $modulus, floor(bcdiv($leftOperand, $modulus, $scale)), $scale ), $scale ); */ Expected result: ---------------- -0.00055999900001 Actual result: -------------- 0.00000000099999 ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=76287&edit=1