Parse unevaluated integral from giac

[mforets]

If integrate(..., algorithm='giac') does not find a solution, Sage should return an unevaluated expression.

For example, consider integrate(exp(-x^2)*log(x), x, algorithm='giac').

It returns either

Traceback (most recent call last):
...
NotImplementedError: Unable to parse Giac output: integrate(ln(x)*exp(-x^2),x)

or

integration(e^(-x^2)*ln(x), x)

depending on the user's locale settings (EN and FR respectively).

OTOH, both Maxima and SymPy return integrate(e<sup>(-x</sup>2)*log(x), x).

Component: calculus

Keywords: integrate, interfaces, giac

Author: Marcelo Forets

Branch/Commit: 0e5bdf0

Reviewer: Steven Trogdon

Issue created by migration from https://trac.sagemath.org/ticket/22997

[mforets]

Commit: f3c9d15

[mforets]

Branch: u/mforets/22997

[mforets]

comment:1

does it correspond at the level or giac_integrator (see symbolic/integration/external.py)? or at the level of the giac interface? (see def _sage_(self, locals={})).

in the former case, is this correct?

...
if 'integrate' in format(result) or 'integration' in format(result):
    return integrate(expr, v, a, b, hold=True) # ???
else:
    return result._sage_()

---

New commits:

f3c9d15

add one doctest

[sagetrac-git]

Changed commit from f3c9d15 to 2bba41d

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

2bba41d

parse result in giac_integrator

[strogdon]

comment:4

Perhaps this exposes a bug in sympy_integrator. These work

sage: integrate(e^(-x^2)*log(x), x, algorithm='giac')
integrate(e^(-x^2)*log(x), x)
sage: integrate(e^(-x^2)*log(x), x, algorithm='maxima')
integrate(e^(-x^2)*log(x), x)

although algorithm='maxima' was not doctested, but

integrate(e^(-x^2)*log(x), x, algorithm='sympy')

just hangs.

[mforets]

comment:5

here it works only after a looong time:

sage: integrate(e^(-x^2)*log(x), x, algorithm='sympy') # 15-20 minutes, processor intensive
integrate(e^(-x^2)*log(x), x)

[strogdon]

Reviewer: Steven Trogdon