[GiNaC-list] code: extended gcd

[Ralf Stephan]

Hello,

> >          gcd(a,b) = ca*a + cb*b.
> 
> These are not the cofactors (at least, I've never seen the quantities from
> this equation referred to as "cofactors").

Heh. See C. Yap, Algorithmic Algebra, Ch. 2, §2, p. 5 which is online:
http://www.cs.nyu.edu/yap/book/
He agrees with you in that the algorithm to compute them is handled
separately from the treatise of gcd computation. Voilà, extgcd.

Now, we are back at square one where I just sent the xgcd() function
to the list. But it had a bug. If you want to have the corrected version
in GiNaC, I will send it gladly and directly to you.


ralf