[Numpy-discussion] matrix multiplication A x, x has some zeros
Alan G Isaac
aisaac@american....
Fri Dec 14 17:53:46 CST 2007
>> idx=N.ravel(x)!=0
>> A[:,idx]*x[idx]
On Fri, 14 Dec 2007, dmitrey apparently wrote:
> I expect <A,x> being vector of length n A and x change
> every iter. A is not sparse.
Still, whenever x has a lot of zeros,
this should have a substantial payoff.
That seems the only exploitable information
you have offered in the problem.
Cheers,
Alan
More information about the Numpy-discussion
mailing list