On Aug 21, 2009, at 1:47 PM, William Stein wrote: > On Thu, Aug 20, 2009 at 1:37 PM, Golam Mortuza Hossain > <gmhoss...@gmail.com> wrote: > > Hi, > > On Thu, Aug 20, 2009 at 3:03 PM, Jason Grout<jason- > s...@creativetrax.com> wrote: > >> I guess, a policy decision is involved here as to whether use > mathematical > >> identities by default or as an option during comparison. To > clarify: > >> > >> ex = sin(x)^2 + cos(x)^2 - 1 > >> > >> In pynac, for above expression "ex.is_zero()" test will result > False by default > >> where as current maxima based comparison will return True. > >> > >> Personally, I feel we should have a flag something like > >> > >> (1) ex.is_zero(use_identity=False) > >> > > perhaps ex.is_zero(simplify=False) ? > > > Yes, thats even better. > > So the next BIG question is what should be the *default* value > of this flag for comparison? In other words, by default do we call > maxima or accept pynac's False return as definitive? > > Personally, I am for accepting pynac's answer by default as it > would massively speed up test like "if x in list" for symbolics. > > We must default to pynac, in my opinion. The question then just > becomes > how to make pynac's comparison better.
Once pynac's comparison is as good as maximas, it may well be just as slow as well, so I'm not sure this solves the problem. We should, of course, be asking pynac if they're equal first. - Robert --~--~---------~--~----~------------~-------~--~----~ To post to this group, send an email to sage-devel@googlegroups.com To unsubscribe from this group, send an email to sage-devel-unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-devel URLs: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
