mpz_gcd_ext(NULL, ...)

Marc Glisse marc.glisse at
Sat Dec 3 03:35:41 UTC 2016

On Sat, 3 Dec 2016, Marco Bodrato wrote:

> The modified manual now says that "If @var{s}, @var{t} or @var{g} is
> @code{NULL} then that value is not computed.", but g is computed anyway,
> even if it is not returned...

The only change is that it is about g, s and t instead of just t. But that 
was already not quite true before, since depending on a < b or b < a, we 
swap the arguments and the mpn function ends up computing t anyway. We are 
saving the copy, which counts as computation, so the formulation seemed 
good enough to me, and most importantly easy to understand for a user. If 
you want to rewrite it to clarify that the gains aren't much, please go 

Marc Glisse

More information about the gmp-devel mailing list