Description:
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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:
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//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:
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The correct result must be zero!

Actual result:
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8.520961714E-15 and 1.42108547152E-14 respectively.