Doctest conversion from SymPy of unevaluated integrals

[eviatarbach]

When SymPy can't evaluate an integral, such as integrate((log(x)*log(log(x))), x, algorithm='sympy'), it returns "AttributeError: 'Integral' object has no attribute 'sage'". It should just return an unevaluated integral, the way it does when Maxima is used.

Another example from #15256:

sage: a = integrate(sin(x)*tan(x), x, algorithm='sympy') 
...

 
/usr/local/sage/sage-5.11/local/lib/python2.7/site-packages/sage/symbolic/integration/external.pyc in sympy_integrator(expression, v, a, b)
     37     else:
     38         result = sympy.integrate(ex, (v, a._sympy_(), b._sympy_()))
---> 39     return result._sage_()
     40
     41 def mma_free_integrator(expression, v, a=None, b=None):
 
AttributeError: 'Integral' object has no attribute '_sage_'
sage: 
sage: 
sage: %debug
> /usr/local/sage/sage-5.11/local/lib/python2.7/site-packages/sage/symbolic/integration/external.py(39)sympy_integrator()
     38         result = sympy.integrate(ex, (v, a._sympy_(), b._sympy_()))
---> 39     return result._sage_()
     40 
 
ipdb> print result
Integral(sin(x)*tan(x), x)

Depends on #20204

CC: @kcrisman @asmeurer @williamstein

Component: calculus

Keywords: sympy, integrate

Author: Ralf Stephan

Branch/Commit: 119f46f

Reviewer: Travis Scrimshaw

Issue created by migration from https://trac.sagemath.org/ticket/14723

[eviatarbach]

comment:1

Attachment: 14723.patch.gz

With the patch, integrate(log(x)*log(log(x)), x) is returned.

[asmeurer]

comment:7

Just looking at the patch, that doesn't look like it does the right thing for definite integrals.