Sympy: Assuming infinity ... Real vs. Complex

[bitbucketboss]

Hi,

Is it possible to distinguish between real and complex infinity using assumptions?

For example:

Symbol("real_infinite", real=True, infinite=True)
Symbol("complex_infinite", complex=True, infinite=True)

, both result in InconsistentAssumptions exceptions?

Thank you.

[asmeurer]

real and complex both mean finite numbers. For real infinities, use extended_real (or extended_positive and so on). I think we decided to defer adding extended_complex until it was clear whether or not we needed it (see discussions at https://github.com/sympy/sympy/issues/17224 and some of the related PRs).

However, if you just want something that is complex and not finite, I believe infinite=True itself implies that it is a "complex infinity", so you can just use Symbol('complex_infinite', infinite=True).

[oscarbenjamin]

I think infinite=True is close as you can get with the current predicates. The precise meaning of infinite=True is not really spelled out though and it is consistent with oo and -oo even though those are not the same as zoo.

[asmeurer]

I'm not even sure if the exact meaning of complex infinities is spelled out. SymPy is apparently able to represent directional infinities like oo*I or exp(I*pi/3)*oo, but it isn't clear if these are meaningful or if they are only supported by accident (e.g., oo + oo*I is allowed, but is probably meaningless).

[bitbucketboss]

Thank you for the clarification.