Re: Octave QR factorization

[John W. Eaton]

On 17-Dec-2003, address@hidden <address@hidden> 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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