OK. Thanks. On Monday, November 9, 2015 at 12:42:51 PM UTC+2, Mateusz Paprocki wrote: > > Hi, > > On 9 November 2015 at 09:49, Paul Royik <distan...@gmail.com <javascript:>> > 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+un...@googlegroups.com <javascript:>. > > To post to this group, send email to sy...@googlegroups.com > <javascript:>. > > 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. >
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