Comment #5 on issue 1127 by asmeurer:
integrate(2*a/((((2*a)**2+x**2))**(3/2)),x) gives traceback
http://code.google.com/p/sympy/issues/detail?id=1127
And here is yet another one. Expanding the expression makes it pass. It
looks like the algorithm is making
some kind of invalid assumption that the expression can be made into a
polynomial when it cannot. I have no
idea how risch works, so I cannot say why this is or how to fix it.
>>> integrate(-(8 + 2*sin(x) + 6*exp(x))*exp(2*x), x)
Traceback (most recent call last):
File "<console>", line 1, in <module>
File "./sympy/utilities/decorator.py", line 56, in threaded_decorator
return func(expr, *args, **kwargs)
File "./sympy/integrals/integrals.py", line 485, in integrate
return integral.doit()
File "./sympy/integrals/integrals.py", line 134, in doit
antideriv = self._eval_integral(function, x)
File "./sympy/integrals/integrals.py", line 315, in _eval_integral
h = heurisch(g, x, hints=[])
File "./sympy/integrals/risch.py", line 280, in heurisch
a, b, c = [ p.as_poly(*V).degree for p in [s, P, Q] ]
AttributeError: 'NoneType' object has no attribute 'degree'
>>> integrate(expand(-(8 + 2*sin(x) + 6*exp(x))*exp(2*x)), x)
2⋅x 2⋅x
4⋅ℯ ⋅sin(x) 2⋅x 2⋅cos(x)⋅ℯ 3⋅x
- ───────────── - 4⋅ℯ + ───────────── - 2⋅ℯ
5 5
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