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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
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From: elliot at essentialsystems dot co dot uk
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 [2014-09-22 10:10 UTC] elliot at essentialsystems dot co dot uk
The calculation in the test script should return 34, but yet is returning back 33.999999999998, which is very odd.

Test script:
//expecting 34
var_dump((40120.7 - 36346.0)-3740.7);

Expected result:
Return back of the value of 34.

Actual result:


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 [2014-09-22 10:13 UTC]
-Status: Open +Status: Not a bug
 [2014-09-22 10:13 UTC]
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:

Thank you for your interest in PHP.

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