Sympy minus infinity doesn't convert to Sage

[kcrisman]

sage: a,b = oo, -oo
sage: a._sympy_()
oo
sage: b._sympy_()
--------------------------------------------
AttributeError                            Traceback (most recent call last)

/Users/.../sage-4.7.2/local/lib/python2.6/site-packages/sage/structure/element.so in sage.structure.element.Element.__getattr__ (sage/structure/element.c:2840)()

AttributeError: 'MinusInfinity' object has no attribute '_sympy_'

See this ask.sagemath.org question for background.

CC: @certik @rwst

Component: symbolics

Keywords: sd40.5

Author: Douglas McNeil

Branch/Commit: u/akhi/sympy_minus_infinity_doesn_t_convert_to_sage @ 52db42b

Reviewer: Karl-Dieter Crisman

Merged: sage-5.1.beta4

Issue created by migration from https://trac.sagemath.org/ticket/12345

[sagetrac-dsm]

Changed keywords from none to sd40.5

[sagetrac-dsm]

comment:1

Straightforward fix and test of the original case as an integral.

[kcrisman]

comment:2

Umm, even without this patch I get

sage: import sympy
sage: bool(SR(-oo) == -sympy.oo)
True
sage: bool(-oo == -sympy.oo)
True

Am I missing something? How is that an indirect doctest?

That said, the integral works fine now and the tests pass.

[kcrisman]

Reviewer: Karl-Dieter Crisman

[kcrisman]

Author: Douglas McNeil

[sagetrac-dsm]

comment:3

Ah, those were merely mirroring the +oo cases. Really they were only testing whether the negation worked; it was the integral test which was really verifying the success. However, we can test it explicitly by adding.

    sage: bool((-oo)._sympy_() == -sympy.oo)
    True

which fails without the patch. Modified to incorporate this.

[kcrisman]

comment:4

Positive review.