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Date: Thu, 23 Aug 2007 16:28:09 +0100
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Subject: Testing math functions
From: zoe.slattery@googlemail.com (Zoe Slattery)

Hi - I've writing a few tests for the math extension and have a question 
about floating point precision.

Here's a small example:

--TEST--
Test return type and value for expected input sin()
--INI--
precision = 14
--FILE--
<?php

$threesixty = pi() * 2.0;
echo "sin 360 = ";
var_dump(sin($threesixty));

?>
--EXPECT--
sin 360 = float(-2.4492127076448E-16)

Is it right to test for an exact number in this way? I was slightly 
suprised that I got the same number from Windows and Linux (maybe I 
shouldn't be).

If not, I could write the test above to check that sin 360 is zero 
plus/minus some small number - but how small?

Zoe Slattery
IBM