From help-octave-request at bevo dot che dot wisc dot edu Wed Dec 17 14:41:01 2003
Subject: Re: Octave QR factorization
From: "John W. Eaton" <jwe at bevo dot che dot wisc dot edu>
To: taltman at lbl dot gov
Cc: Bart Vandewoestyne <Bart dot Vandewoestyne at pandora dot be>,    help-octave@bevo.che.wisc.edu
Date: Wed, 17 Dec 2003 14:40:34 -0600

On 17-Dec-2003, taltman at lbl dot gov <taltman@lbl.gov> wrote:

| * Matlab does some behind-the-scenes tweaking of their definition of
|   equality on reals depending on the OS/hardware/software combination.

I hope not, because if two numbers compare equal, I expect that
comparison to be good right down to the last bit.  If you want fuzzy
comparison, then you should be using something other than ==.

If Matlab gets it "right" on x86 hardware, then perhaps it does not
use the internal 80-bit register operations.  Does anyone know of a
way to do that with gcc without using -ffloat-store?  (I'd rather not
use -ffloat-store by default due to the potential performance
penalty.)

jwe



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