[MPFR] multiplications vs. subtractions: which one is faster?

Linas Vepstas linas at austin.ibm.com
Wed Jul 18 18:20:13 CEST 2007

On Wed, Jul 18, 2007 at 12:15:32AM +0200, Vincent Lefevre wrote:
> On 2007-07-15 10:54:03 +0200, Paul Zimmermann wrote:
> > Thank you Patrick. However I'd like to point out that those figures
> > (I mean the ratio of the number of cycles for both variants) might
> > vary from one platform to the other, maybe by more than a factor of
> > two. They might also depend on the version of mpfr, on the fact that
> > GMP and/or MPFR were tuned for that platform, and on the actual
> > operand values
> Yes, that's why it is better to implement both solutions and compare
> them.

It also helps with debugging and validation: both algos should return
identical results!


More information about the gmp-discuss mailing list