On 2013-01-25, Dima Pasechnik <[email protected]> wrote: > On 2013-01-25, Volker Braun <[email protected]> wrote: >> ------=_Part_681_2503209.1359120527992 >> Content-Type: text/plain; charset=ISO-8859-1 >> >> On Friday, January 25, 2013 1:11:15 PM UTC, Dima Pasechnik wrote: >> >>> If I read what Volker noticed right, in this code the bulk of time is >>> spent computing the order of a group of 2x2 matrices by converting it >>> into a permutation group, via GAP. And the order of the group is never >>> more than 342 here. A naive algorithm, enumerating the >>> elements of the matrix group directly, would speed this up hugely, IMHO. >> >> >> Or port the matrix groups to libgap... > no, that's won't help, as that's what GAP does internally! > you can do profiling of GAP on your example: > http://www.gap-system.org/Manuals/doc/ref/chap7.html#X7FDF923D7D2937A1 > and see what happens... > (just use ProfileGlobalFunctions(True) before running the thing to be > profiled, and ProfileGlobalFunctions() to see the result) > on your example on http://tracker.gap-system.org/issues/221 it's actually about 4 times faster to call Size(Elements(G)) (this just naively enumerates the elements) than Order(G) (this constructs a permutation group along the way)
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