On Mon, Apr 4, 2011 at 9:41 AM, Terry Reedy <tjre...@udel.edu> wrote: > On 4/4/2011 1:51 AM, Paul Rubin wrote: > >> I didn't realize Python used Karatsuba. The main issue is probably that >> Python uses a straightforward portable C implementation that's not >> terribly efficient, > > but relatively easy for a couple of people to maintain. For (C)Python 3, > which no longer has a C int type, I believe changes were focused on making > calculations with small integers almost as fast as in 2.x. > > (I believe that retaining two implementations internally was considered but > rejected. Could be wrong.)
There are two implementations, grade school multiplication and karatsuba, which kicks in after a given cutoff. >>If you look for the gmpy module, it gives you a way to use gmp from >>Python. In crypto code (lots of 1024 bit modular exponentials) I think >>I found gmpy to be around 4x faster than Python longs. > > For specialized use, specialized gmpy is the way to go. > > I am curious how gmpy compares to 3.x ints (longs) with small number > calculations like 3+5 or 3*5. I have this data somewhere, if you're interested I'll try to dredge it up. Geremy Condra -- http://mail.python.org/mailman/listinfo/python-list
