Bug #68070 [Opn->Nab]: Wrong Answer to a fairly standard calculation

Edit report at https://bugs.php.net/bug.php?id=68070&edit=1 ID: 68070 Updated by: nikic@php.net Reported by: elliot at essentialsystems dot co dot uk Summary: Wrong Answer to a fairly standard calculation -Status: Open +Status: Not a bug Type: Bug Package: Math related Operating System: Ubuntu PHP Version: Irrelevant Block user comment: N Private report: N New Comment: Floating point values have a limited precision. Hence a value might not have the same string representation after any processing. That also includes writing a floating point value in your script and directly printing it without any mathematical operations. If you would like to know more about "floats" and what IEEE 754 is, read this: http://www.floating-point-gui.de/ Thank you for your interest in PHP. Previous Comments: ------------------------------------------------------------------------ [2014-09-22 10:10:04] elliot at essentialsystems dot co dot uk Description: ------------ The calculation in the test script should return 34, but yet is returning back 33.999999999998, which is very odd. Test script: --------------- <?php //expecting 34 var_dump((40120.7 - 36346.0)-3740.7); ?> Expected result: ---------------- Return back of the value of 34. Actual result: -------------- 33.999999999998 ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=68070&edit=1