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Re: Firefox 2.0.0.7 has a very serious calculation bug


From: Daniel Veditz <dveditz () cruzio com>
Date: Fri, 28 Sep 2007 10:43:12 -0700

carl hardwick wrote:
PoC concept here:
javascript:5.2-0.1
(copy this code into address bar)

Firefox 2.0.0.7 result: 5.1000000000000005 (WRONG!)
Internet Explorer 7 result: 5.1 (OK)

In IE7 and Opera I get the same thing you do for Firefox. This is not
surprising because the ECMAScript specification says that floating point
operations must comply with ANSI/IEEE Std 754-1985: IEEE Standard for
Binary Floating-Point Arithmetic.

The ECMAScript version 4 proposal introduces a decimal type intended to fix
up some of weirdness caused by mapping base-2 floating point rounding back
into base-10 notation.

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