php.net |  support |  documentation |  report a bug |  advanced search |  search howto |  statistics |  random bug |  login

go to bug id or search bugs for

Bug #68070 Wrong Answer to a fairly standard calculation
Submitted: 2014-09-22 10:10 UTC Modified: 2014-09-22 10:13 UTC
From: elliot at essentialsystems dot co dot uk Assigned:
Status: Not a bug Package: Math related
PHP Version: Irrelevant OS: Ubuntu
Private report: No CVE-ID: None
View Add Comment Developer Edit
Welcome back! If you're the original bug submitter, here's where you can edit the bug or add additional notes.
If this is not your bug, you can add a comment by following this link.
If this is your bug, but you forgot your password, you can retrieve your password here.
Password:
Status:
Package:
Bug Type:
Summary:
From: elliot at essentialsystems dot co dot uk
New email:
PHP Version: OS:

 

 [2014-09-22 10:10 UTC] 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

Patches

Add a Patch

Pull Requests

Add a Pull Request

History

AllCommentsChangesGit/SVN commitsRelated reports
 [2014-09-22 10:13 UTC] nikic@php.net
-Status: Open +Status: Not a bug
 [2014-09-22 10:13 UTC] nikic@php.net 
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.
 
PHP Copyright © 2001-2023 The PHP Group
All rights reserved. 		Last updated: Thu Dec 07 14:01:28 2023 UTC