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From: Charles Sandmann <sandmann AT clio DOT rice DOT edu>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Cross Platform Incompatabilites?
Date: Sun, 08 Feb 2004 22:01:00 CST
Organization: Rice University, Houston, TX
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> The differences are *possibly* generated in a routine which calculates the
> integral under the curve of FFT*FFT*2, using the trapezoidal rule.  The
> error appears in only one integration of a calculation of probably a
> hundred integrations.  The integration routine does not seem to have errors.  

I would suggest adding the line:
 int _crt0_startup_flags = _CRT0_FLAG_FILL_DEADBEEF;
to your main program.  Does this cause all platforms to behave the same?
(get the same answers?)  This flag helps find differences due to 
uninitialized memory, which may be different values on different 
platforms.