Thanks a lot for the response. In the end I have decided not to include the optimisations in the article, since they are complicated and difficult to understand. I don't think we want to make things more complicated in an article that focuses on potential new PDL users.
Your explanations on the performance hit seems reasonable. I will try with smaller arrays, as soon as I have finished writing the article :=) Cheers, Xavier On 3/14/07, zowie <[EMAIL PROTECTED]> wrote:
There's another aspect to this, which is that for() loops in Perl aren't so slow. IDL's interpreter is mired in molasses compared to Perl's, so Perl loops don't impose quite the same performance hit as IDL loops. (Of course, we all like PDL's threading engine much better anyway... :-) On Mar 1, 2007, at 3:45 PM, Karl Glazebrook wrote: > Either bad coding or some intrinsically unvectorisable. > > These sort of slow downs are of order right in the situation where > you are stepping from an array pixel by pixel with a for() loop. > One comparison which would be useful of IDL vs PDL is how often you > need to resort to the for() loop, PDL I think has more language > tricks. > > Karl > > On 01/03/2007, at 6:38 PM, Frossie wrote: > >> >> Well, this is slighly anecdotal, but: >> >> We have at least one experience of the same algorithm implemented in >> IDL and in C, and the difference was significantly more than your >> example (of the order of a minute v. an hour), though as we did not >> implement the IDL version ourselves it could have been poor coding on >> their part. >> >> My point is that if you wanted to say something substantive you >> should >> try a range of algorithmic problems. > > > _______________________________________________ > Perldl mailing list > [email protected] > http://mailman.jach.hawaii.edu/mailman/listinfo/perldl > _______________________________________________ Perldl mailing list [email protected] http://mailman.jach.hawaii.edu/mailman/listinfo/perldl
_______________________________________________ Perldl mailing list [email protected] http://mailman.jach.hawaii.edu/mailman/listinfo/perldl
