Re^5: Why is this code so much slower than the same algorithm in C? (2s)

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Re^6: Why is this code so much slower than the same algorithm in C? (2s) by tye (Sage) on Dec 12, 2008 at 03:31 UTC
Yes, thanks. The "last until $i%..." logic has so many negations in it (many of them implicit rather than explicit) that it took several iterations to work out some stuff that I had backwards. Limbic~Region and others in the chatterbox helped out and pointed out that keeping 8 while dropping 16 was backward. But my error of keeping 3 while dropping 9 was not caught (and when I went to check my work, I did not see that anybody had reported the output of their lengthy test runs, just the running times, and I had things to do and so made no plans to tie up my computer for minutes in order to get the answer for comparison). I'll update the node to note the require `s/3/9/`. Thanks again. - tye	[reply] [d/l]

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Re^6: Why is this code so much slower than the same algorithm in C? (2s)
by tye (Sage) on Dec 12, 2008 at 03:31 UTC

Yes, thanks. The "last until $i%..." logic has so many negations in it (many of them implicit rather than explicit) that it took several iterations to work out some stuff that I had backwards. Limbic~Region and others in the chatterbox helped out and pointed out that keeping 8 while dropping 16 was backward. But my error of keeping 3 while dropping 9 was not caught (and when I went to check my work, I did not see that anybody had reported the output of their lengthy test runs, just the running times, and I had things to do and so made no plans to tie up my computer for minutes in order to get the answer for comparison).

I'll update the node to note the require s/3/9/. Thanks again.

- tye

[reply]
[d/l]