I am just having difficulty wrapping my head around zoo - zoo. Complex infinity should be unsigned. And even if you did write something like this should this be nan or zoo?
Otoh, since zoo - zoo doesnt make sense, S.NaN should actually be the correct answer. Can someone more knowledgeable about this enlighten me? On Apr 18, 4:36 pm, "Alexey U. Gudchenko" <[email protected]> wrote: > 18.04.2011 08:20, smichr пишет: > > > Does zoo absorb everything in an addition or multiplication (except > > maybe oo or another zoo)? > > It is related with this old > issue:http://code.google.com/p/sympy/issues/detail?id=360 > > And with this open pull request:https://github.com/sympy/sympy/pull/173/files > > E.g. Those assertions have quit right behavior: > > assert zoo == zoo > assert zoo != oo > assert 1*zoo == zoo > assert 2*zoo == zoo > assert 1 != zoo > assert zoo != 1 > assert zoo != Symbol("x")**3 > assert zoo + 1 == zoo + 1 > assert zoo + 1 == zoo > assert 2 + zoo == zoo > assert 3*zoo + 2 == zoo > assert 1/zoo == 0 > > x = Symbol('x') > > assert zoo + zoo == nan > assert zoo - zoo == nan > assert zoo + oo == nan > assert zoo - oo == nan > > assert zoo + I == zoo > assert zoo * I == zoo > assert zoo + x + 2 + 3*I == zoo + x > assert zoo * x * 2 * 3*I * -oo == zoo * x > > assert zoo * (1+I) == zoo > assert zoo * (4+I+x) != zoo > > assert zoo * 0 == nan > assert zoo * nan == nan > assert 0 * zoo == nan > assert nan * zoo == nan > assert zoo + nan == nan > > assert zoo**zoo == nan > assert zoo**0 == nan > assert zoo**2 == zoo > assert zoo**(-1) == 0 > > assert abs(zoo) == oo > > If anyone disagree with those assertions please let us know. > > -- > Alexey U. -- You received this message because you are subscribed to the Google Groups "sympy" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/sympy?hl=en.
