|Bill Allombert on Wed, 23 Apr 2003 19:22:46 +0200|
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|Re: group identification patch|
On Wed, Apr 23, 2003 at 11:21:14AM -0400, Igor Schein wrote: > On Wed, Apr 23, 2003 at 02:20:17PM +0200, Bill Allombert wrote: > > On Tue, Apr 15, 2003 at 11:42:22AM -0400, Igor Schein wrote: > > > On Wed, Apr 02, 2003 at 03:05:49PM +0200, Bill Allombert wrote: > > > > Hello PARI-dev, > > > > > > > > Here a (large) patch that add a feature similar to GAP IdGroup > > > > function for weakly super-solvable group. > > > > > > It worked fine for me in preliminary testing, I'd like to see it > > > committed ASAP. It's a few percentage points faster than the kludge > > > I've devised, and is definitely less cumbersome. > > > > Done. The GP function is galoisidentify and the code is in > > src/modules/groupid.c > > > > Cheers, > > Bill. > > Does it need to be install()'ed? No, it is a GP function (though the PARI function has the same name). ( group_index has been renamed to group_ident). I have just added a function returning the index of the group in the GAP4 transitive group library. This library is limited to degree <=30. This will allows to compute the equivalent of polgalois() for Galois groups, but only when the polynomial is Galois, of course. The function is galois_index_trans() in groupid.c. To use it: default(new_galois_format,1); install("group_ident_trans","lGDG"); galoistrans(G) = [poldegree(G.pol),(-1)^!issquare(poldisc(G.pol)),group_ident_trans([G.gen,G.orders])] Now ? P=x^8 - 12*x^6 + 23*x^4 - 12*x^2 + 1; ? polgalois(P) %19 = [8, 1, 3] ? galoistrans(galoisinit(P)) %20 = [8, 1, 3] Cheers, Bill.