my loop is too slow

[Joe Strout]

In article <Oc1_2.1163$G3.34761 at news14.ispnews.com>, Tim Hochberg
<hochberg at psn.net> wrote:

> >2. If you're doing something that can be expressed in linear algebra,
> >consider using the Numeric module; it is MUCH faster than standard
> >Python at such operations.

> FWIW: Taking into account Michael Haggerty's observation on that this is
> really a matrixmultiply of (c.f)(c.transpose(f)), I reimplemented the
> original loop as:
> 
> from Numeric import *
> a = a + dot(c, f) * dot(c, transpose(f))
> 
> This improved the speed a lot. In fact the above runs in less than a second
> on a P300 machine with len(a)=142.

>From 10 hours to less than a second!  On different machines, of course,
so the two are not really comparable, but even so... this is what I
would call a "significant improvement".

Yay for Numeric!

Cheers,
-- Joe

-- 
,------------------------------------------------------------------.
|    Joseph J. Strout           Biocomputing -- The Salk Institute |
|    joe at strout.net             http://www.strout.net              |
`------------------------------------------------------------------'
Check out the Mac Web Directory!    http://www.strout.net/macweb.cgi