Doc #76287 [Ana->Csd]: 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: Analyzed +Status: Closed Type: Documentation Problem Package: BC math related Operating System: Linux debian PHP Version: 7.2.5 Assigned To: cmb Block user comment: N Private report: N New Comment: This bug has been fixed in the documentation's XML sources. Since the online and downloadable versions of the documentation need some time to get updated, we would like to ask you to be a bit patient. Thank you for the report, and for helping us make our documentation better. Previous Comments: ------------------------------------------------------------------------ [2018-04-30 22:11:15] cmb@php.net Automatic comment from SVN on behalf of cmb Revision: http://svn.php.net/viewvc/?view=revision&amp;revision=344895 Log: Fix #76287: bcmod returns incorrect values ------------------------------------------------------------------------ [2018-04-30 17:20:42] kacper dot rowinski at gmail dot com Tx for info I hope this will be soon added to documentation as it's little confusing. ------------------------------------------------------------------------ [2018-04-30 13:54:06] cmb@php.net 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. ------------------------------------------------------------------------ [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