signsimp didn't seem to help. I'll try to get a gist of the expression up tomorrow, it's so huge I haven't succesfully ran simplify on it. However, I had the same thing happen with a readable expression. The issue was something like:
>>> expr = sin(a)/tan(a) >>> expr.subs(a, 0) nan >>> expr = expr.trigsimp() >>> expr cos(a) >>> expr.subs(a, 0) 1 Based on the form of equations of motion, I assume it's something along this line where a trig identity needs to be subbed out. For large expressions, trigsimp is too slow to actually use, but I can't see a way around it. I tried all methods of trigsimp (interestingly `fu` is faster for small expressions, but `matching` is faster for large). Looking through to see if I can find a way to generate more compact expressions to attempt to avoid this end result. On Friday, June 27, 2014 7:29:48 AM UTC-5, Chris Smith wrote: > > Try only signsimp before substitution. Can you post code to generate one > of these expressions? > -- You received this message because you are subscribed to the Google Groups "sympy" group. To unsubscribe from this group and stop receiving emails from it, send an email to sympy+unsubscr...@googlegroups.com. To post to this group, send email to sympy@googlegroups.com. Visit this group at http://groups.google.com/group/sympy. To view this discussion on the web visit https://groups.google.com/d/msgid/sympy/b744450a-9410-4146-bceb-525dd1d44e42%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
