Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.python > #2542 > unrolled thread

Re: integer multiplication

Back to article view | Back to comp.lang.python

This discussion starts older than the indexed window; earlier articles aren't shown. The article labeled Started by below is the oldest one visible, not the original post.

Contents

  Re: integer multiplication geremy condra <debatem1@gmail.com> - 2011-04-03 18:46 -0700

#2542 — Re: integer multiplication

On Sun, Apr 3, 2011 at 6:41 PM, Eddie Tsay <jianyu44@gmail.com> wrote:
>
> On Sun, Apr 3, 2011 at 6:33 PM, geremy condra <debatem1@gmail.com> wrote:
>>
>> On Sun, Apr 3, 2011 at 6:20 PM, Eddie Tsay <jianyu44@gmail.com> wrote:
>> > Does anyone know what algorithms for integer multiplication does Python
>> > use?
>> > I am trying to compare it to those used by Sage as it seems like it
>> > takes
>> > much longer for Python to do large integer multiplication as compared to
>> > Sage (anyone know off the top of their heads?)
>> > thank you
>>
>> (sorry for the double email, this was supposed to go to the list)
>>
>> Karatsuba multiplication, at least for large integers.
>>
>> Geremy Condra
>
>
> Thank you for replying to my question.
> Do you have any idea how I would be able to find how they do this
> multiplication in the python source code? I've been poking around the
> documentation and can't find the area where they outline it.
> Thank you for your reply =)
> Eddie

In the Python3 source tarball its in Objects/longobject.c. I only have
the 3.2a1 tarball on this machine, but I found the 'grade school'
method implemented in x_mul on line 2765 of that file and karatsuba
multiplication as k_mul on line 2890. YMMV depending on what version
you're looking at.

Just as a side-note, top-posting is considered a minor breach of
netiquette on python-list. I've rearranged the reply correctly here.

Geremy Condra

[toc] | [standalone]

Back to top | Article view | comp.lang.python

csiph-web