Travis E. Oliphant wrote: > Christopher Barker wrote: >> This discussion makes me wonder if the basic element-wise operations >> could (should?) be special cased for contiguous arrays, reducing them to >> simple pointer incrementing from the start to the finish of the data >> block. The same code would work for C and Fortran order arrays, and be >> pretty simple. >> >> This would address Hans' issue, no? >> >> It's a special case but a common one. >> >> > There is a special case for this already. It's just that the specific > operations he is addressing requires creation of output arrays that by > default are in C-order. This would need to change in order to take > advantage of the special case. For copy and array creation, I understand this, but for element-wise operations (mean, min, and max), this is not enough to explain the difference, no ? For example, I can understand a 50 % or 100 % time increase for simple operations (by simple, I mean one element operation taking only a few CPU cycles), because of copies, but a 5 fold time increase seems too big, no (mayb a cache problem, though) ? Also, the fact that mean is slower than min/max for both cases (F vs C) seems a bit counterintuitive (maybe cache effects are involved somehow ?).
Again, I see huge differences between my Xeon PIV @ 3.2 Ghz and my pentium M @ 1.2 Ghz for those operations: pentium M gives more "intuitive results (and is almost as fast, and sometimes even faster than my Xeon for arrays which can stay in cache). cheers, David _______________________________________________ Numpy-discussion mailing list Numpy-discussion@scipy.org http://projects.scipy.org/mailman/listinfo/numpy-discussion
