Hi, On 9 November 2015 at 09:49, Paul Royik <distantjob...@gmail.com> wrote: > In Mul class I see this piece of code: > > def _eval_is_real(self): > real = True > zero = one_neither = False > > for t in self.args: > if not t.is_complex: > return t.is_complex > > > Don't understand last two lines. How is it possible that if t is not > complex, then return that all Mul is not real?
I think this is because t.is_real implies t.is_complex, so saying t.is_complex == False doesn't mean t.is_real == True; it means that t is perhaps not a number (e.g. a MatrixExpr). As we employ three-valued logic (yes, no, don't know), then returning t.is_complex is the correct approach. Also see [1], because this code was originally wrong (perhaps Chris can give you better explanation). [1] https://github.com/sympy/sympy/commit/4d9c756d031e3965867701a65d3970a915495944 Mateusz > -- > 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/cbc7af32-9220-4351-9035-03eeac60a6a2%40googlegroups.com. > For more options, visit https://groups.google.com/d/optout. -- 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/CAGBZUCaiOzEqiB8%2BhvTx94g9GDbMyeH9rpcF1Kb3xFZ9edtOZA%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
