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Re: Linux doubles precision bug?

From: Ian Lance Taylor <iant at google dot com>
To: "Betty Evans" <bevans at ittvis dot com>
Cc: <libstdc++ at gcc dot gnu dot org>
Date: 26 Feb 2008 14:58:07 -0800
Subject: Re: Linux doubles precision bug?
References: <B1B624F7C110834B96594065A74F3A5407EBA0D8@gemini.rsinc.com>

"Betty Evans" <bevans@ittvis.com> writes:

> Running the same code gives me different results on Linux 32 bit and 64
> bit computers.  I'm not sure if it is a bug or not but other compilers
> give the same results when run on 32 and 64-bit systems.

This question would be better directed to the mailing list
gcc-help@gcc.gnu.org.  Please take any followups there.  Thanks.

You didn't mention the processor, but let's assume it's x86.  On x86,
32-bit floating point code uses the x87 registers with 80-bit
precision.  64-bit floating point code uses the SSE registers with
64-bit precision.  Different results are normal and expected.

You may find it interesting to look at http://gcc.gnu.org/PR323 .

Ian

References:
- Linux doubles precision bug?
  - From: Betty Evans

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