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gap calls seem to consume a lot of time

asked 2011-04-02 13:30:45 +0100

parzan gravatar image

updated 2011-06-21 10:45:56 +0100

I am trying to migrate some code from GAP to sage, and the overhead for calls to GAP procedures is enormous. Here is an example:

| Sage Version 4.6.2, Release Date: 2011-02-25                       |
| Type notebook() for the GUI, and license() for information.        |
sage: def test1():
....:     for x in xrange(100): gap.eval('G:=Group([(1,2,3)])')
sage: def test2():
....:     gap.eval('for x in [1..100] do G:=Group([(1,2,3)]);od')
sage: timeit('test1()')
5 loops, best of 3: 810 ms per loop
sage: timeit('test2()')
25 loops, best of 3: 12.6 ms per loop

Is there anything I am doing wrong?

I tried some profiling, which indicated that most of the time is consumed by "".

Any help will be most welcome.

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answered 2011-04-02 14:24:39 +0100

DSM gravatar image

Yep, the gap interface is pretty slow, due to the I/O approach (hence the time in Fortunately for lots of use cases this isn't the bottleneck, but in some cases it can be, more's the pity. Work on a faster Cythonic interface is progressing -- see -- but it's not quite there yet.

Instead of calling a gap function explicitly to build a permutation group, it's more idiomatic Sage to write

G = PermutationGroup([(1,2,3)])

which can be a little faster (~2x, maybe). Underlying problem is still there, though.

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Thanks for replying! Actually, the code I gave was just for example. The functions I'm interested in are within a GAP package called FGA (free group algorithms), and I don't think there is any parallel in sage (but I'll be glad to be corrected). In any case, the libGAP link gives me something to wait for!

parzan gravatar imageparzan ( 2011-04-02 18:49:54 +0100 )edit

libGAP is feature-complete. You are more than welcome to test the current version and help review it.

Volker gravatar imageVolker ( 2011-04-03 20:51:44 +0100 )edit

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Asked: 2011-04-02 13:30:45 +0100

Seen: 502 times

Last updated: Apr 02 '11