Re: Sine and Cosine Accuracy on AMD64 and Pentium 4

=?ISO-8859-1?Q?J=FCrgen_Kahrs?= <Juergen.Kahrs@vr-web.de>
17 Jul 2005 20:45:31 -0400

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Sine and Cosine Accuracy on AMD64 and Pentium 4 scott.ladd@coyotegulch.com (Scott Robert Ladd) (2005-05-26)
Re: Sine and Cosine Accuracy on AMD64 and Pentium 4 gah@ugcs.caltech.edu (glen herrmannsfeldt) (2005-05-28)
Re: Sine and Cosine Accuracy on AMD64 and Pentium 4 jcrens@earthlink.net (Jack Crenshaw) (2005-07-17)
Re: Sine and Cosine Accuracy on AMD64 and Pentium 4 Juergen.Kahrs@vr-web.de (=?ISO-8859-1?Q?J=FCrgen_Kahrs?=) (2005-07-17)
Re: Sine and Cosine Accuracy on AMD64 and Pentium 4 gah@ugcs.caltech.edu (glen herrmannsfeldt) (2005-07-22)
Re: Sine and Cosine Accuracy on AMD64 and Pentium 4 henry@spsystems.net (2005-07-26)
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From: =?ISO-8859-1?Q?J=FCrgen_Kahrs?= <Juergen.Kahrs@vr-web.de>
Newsgroups: comp.compilers
Date: 17 Jul 2005 20:45:31 -0400
Organization: Compilers Central
References: 05-05-215 05-07-075
Keywords: arithmetic

Jack Crenshaw wrote:


> 1) are you sure your value of pi is not part of the problem?
> I have always been told to let the numeric processor set
> its own value, which it knows internally at 80-bit accuracy.
> You can get that value using something like
>
> pi = 4 * atan(1);


When using POSIX C, you can also use M_PI


    http://www.opengroup.org/onlinepubs/009695399/basedefs/math.h.html


With other languages (like awk) I also use 4 * atan2(1,1).
atan2 (as opposed to atan) is 'more standard'.


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