8 Nov
2004
8 Nov
'04
5:21 p.m.
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