I created a ticket #13461 with a patch that is another large speedup in WeylCharacterRings.
The workhorse in WeylCharacterRings is (was) the Freudenthal multiplicity formula that computes the character of an irreducible representation. It occurred to me that after some one-time arithmetic (not in a loop) a Demazure character can be computed using only integer addition and subtraction, and it might be fast, so I tried it. If you run sage -t --long weyl_characters.py it is more that twice as fast: about 2.5 times as fast. If you omit the --long, it is slightly slower, so the speedup is mainly for big calculations. As a biproduct, you get Demazure characters as a new method of the WeylCharacterRing. self.demazure_character(weight, word) thus produces an element of the WeightRing. This enhancement is only for WeylCharacterRings created using style="coroots". That means that we can do Demazure characters for SL(n) but not GL(n). This could be fixed, but generalizing the method to the reductive case would require carrying a bit more data around, and we might lose the speedup. So if you omit style="coroots" when you create the WeylCharacterRing, it reverts to the old method using the Freudenthal multiplicity formula. Dan -- You received this message because you are subscribed to the Google Groups "sage-combinat-devel" group. To view this discussion on the web visit https://groups.google.com/d/msg/sage-combinat-devel/-/Up4XVeo0XwUJ. To post to this group, send email to sage-combinat-devel@googlegroups.com. To unsubscribe from this group, send email to sage-combinat-devel+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sage-combinat-devel?hl=en.
