Dear Forum, Dear Gordon, GAP always calls a randomized Schreier-Sims but then calls a verification routine. I suspect GAP is in this verification routine. (You could interrupt with CTRL-C and call Where(500) to see the function callback to check.)
Basically there are three ways to get this faster: - Skip most verification: StabChainOptions(G).random:=1; - Assign an order as known: SetOrder(G,9170703360); - Use the genss package (which performs better for huge degree groups but currently has no verification step). Best, Alexander > On Jun 24, 2015, at 6:37 PM, Gordon Royle <gordon.ro...@uwa.edu.au> wrote: > > I have four permutations, each of which has degree 76422528 (for those > interested, this is the degree of a primitive representation of PSp(6,3)). > > The permutations generate a group, which I believe to have order 9170703360 > (this is twice the order of PSp(6,3)). > > For various reasons, I wish to know how the extra factor of 2 is acting. > > > I can read the four permutations into GAP, and I can form the group generated > by them, but now I need to compute with it. > > I have just asked GAP for the order of the group, both for double-checking, > and also so that it sets up the internal data structures needed for further > computation. > > > But now it is sitting there, consuming cpu-time, but with no other indication > of progress. > > Initially it chewed up memory quite quickly for a while, but it has > stabilised and seems to just be grinding on in the same memory footprint - I > left it overnight, and the memory used has been constant. > > > Is there any way that I can guess whether this will finish (a) tonight, (b) > tomorrow, or (c) just before the sun goes supernova? > > Alternatively, can I “help” it by *telling* GAP the order of the group? (In > Magma, I can _assign_ the order of the group and then use RandomSchreier to > generate a bases/s.g.s). Of course, I lose the double-checking aspect of > things, but I’m willing to do that if necessary. > > > Thanks > > Gordon > > > > > > > > > > > > > > > > > > > > _______________________________________________ > Forum mailing list > Forum@mail.gap-system.org > http://mail.gap-system.org/mailman/listinfo/forum _______________________________________________ Forum mailing list Forum@mail.gap-system.org http://mail.gap-system.org/mailman/listinfo/forum
