Re: Convolving speed issue

rog...@[EMAIL PROTECTED]
 wrote:
> Dear Paolo,
> yes, it isnt so much slower. I could also use fftw, which is available
> for matlab and also for IDL. But nevertheless, I had to convolve it
> directly and not in frequency domain.

OK, here's where I cannot follow you: why do you care how the
convolution is preformed? If you get the same answer by the
direct (slow) and FFT (fast) method, why would you not want to use
the latter one?

Paolo


>The problem is that the matrices
> could be very large (their size is changing dynamically) and there are
> also some iterations (nearly 200) for each convolve. So I always try
> to use as often as possible reform, replicate and rebin, because those
> are very fast for manipulating or computing arrays.
>
> But, unfortnately I'm not able to exchange the for-to loops
> completely. I think, it's quite difficult to do this in the way I
> mentioned above.
>
> But thanks again for answer, Paolo
>
> Any other ideas?
>
> Best regards
>
> Chris