On Thu, Apr 24, 2014 at 11:58 AM, Matthew Rocklin <[email protected]> wrote: >> >> > We only need things >>> >>> like multi-pattern unification and AC unification. >> >> >> I do not know what exactly these are. >> I read that AC unification can be polynomial, which sounds like a >> potential performance bottleneck; do we really need it? > > > Given expression (like sin(2*x) + cos(2*x)) we need to match against many > possible patterns (like, every known trig identity). It's possible to store > all of the patterns in a good data structure so that we can check them all > simultaneously (see Trie for something similar). We need to do this > matching in a way that is aware of commutative operators (like +). Naive > solutions to this are very slow. There exists sophisticated solutions.
For trig simplification, there is a paper that I think uses some systematic way to simplify it. So it might be that for that you don't need to check all the trig identities. Ondrej -- 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 [email protected]. To post to this group, send email to [email protected]. 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/CADDwiVC3USWwNzPkKAnB%2BPRHff_ZHWZm%2BsBFH84_iZiBVB9G6g%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
