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From:	"Dave Korn" <dk AT artimi DOT com>
To:	<cygwin AT cygwin DOT com>
Subject:	RE: exp() bug?
Date:	Tue, 5 Oct 2004 16:44:02 +0100
MIME-Version:	1.0
In-Reply-To:	<20041005153556.GA712@ingber.com>
Message-ID:	<NUTMEGg5XmllgYBr4Bv00000281@NUTMEG.CAM.ARTIMI.COM>
X-OriginalArrivalTime:	05 Oct 2004 15:44:02.0189 (UTC) FILETIME=[2328A3D0:01C4AAF2]

> -----Original Message-----
> From: cygwin-owner On Behalf Of Lester Ingber
> Sent: 05 October 2004 16:36

> I believe there is a bug in some gcc's, at least in the exp() function,
> and at least in the way round-offs are (in)consistently treated.

  Go on?

> I first noticed some differences in results in calculations using the
> MINGW gcc vs the Cygwin gcc on my ThinkPad XPPro machine.  I applied
> the same code on FreeBsd and on SPARC/Solaris9.

  First go and google for "What every computer scientist should know about
floating point", and read the entire paper.  Then try running your tests again,
but compile them with the "-ffloat-store" option.  Then read "info gcc" about
-ffloat-store and its effects.

  Then if you still think there's a bug, come back and describe it.  But if you've
taken all that in, you no longer will.

    cheers, 
      DaveK
-- 
Can't think of a witty .sigline today....


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