On Tue, Aug 26, 2008 at 12:49 AM, William Stein <[EMAIL PROTECTED]> wrote: > >> BTW, one important warning: ginac and sympycore are missing >> assumptions and sympy only has very trivial ones, like positive, >> negative, integer, even, odd, etc. This is really important for any >> nontrivial things in a CAS and I changes to the core may be needed. I >> really want to have assumptions in sympy first before saying -- yes, >> this approach to do the core is the best. >> >> Ondrej > > Why are assumptions "really important for any nontrivial things in a CAS"? > In my entire life I've only ever used assumptions to get maxima to do > a symbolic integration. I've never used them in any other context. > Can you please educate me on why they are so important? Thanks.
Basically all more nontrivial simplifications. Things like to simplify sqrt(1-sin(x)**2) etc. Or acos(cos(x)). All of those are things that are needed to be automatic, but only work sometimes, e.g. if 0 < x < pi, or -pi/2 < x < pi/2 etc. This is obivously needed in integration and in solvers and also just when the user wants to simplify the expression. So in particular this is done inside ginac, so ginac need some way to handle these. Do you have any ideas how to do it? Ondrej --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-devel@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sage-devel URLs: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
