Bug #51480 [Opn->Bgs]: Error on calculation 100.2 - 100.1 - 0.1

Edit report at http://bugs.php.net/bug.php?id=51480&edit=1 ID: 51480 Updated by: pajoye@php.net Reported by: vinilazev at gmail dot com Summary: Error on calculation 100.2 - 100.1 - 0.1 -Status: Open +Status: Bogus Type: Bug Package: Math related Operating System: Linux PHP Version: Irrelevant 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://docs.sun.com/source/806-3568/ncg_goldberg.html Thank you for your interest in PHP. Previous Comments: ------------------------------------------------------------------------ [2010-04-05 16:43:18] vinilazev at gmail dot com Description: ------------ Error on a simple calculation. The correct result must be zero. Google and JavaScript are wrong too. But OpenOffice Calc and GCalcTool (gnome calculator) are correct. Test script: --------------- //Try a simple calculation: $result = 100.2 - 100.1 - 0.1; echo $result; //The result is 8.520961714E-15 //And trying (inverting): $result = 100.2 - 0.1 - 100.1; echo $result; //The result is 1.42108547152E-14 Expected result: ---------------- The correct result must be zero! Actual result: -------------- 8.520961714E-15 and 1.42108547152E-14 respectively. ------------------------------------------------------------------------ -- Edit this bug report at http://bugs.php.net/bug.php?id=51480&edit=1