Status: Valid
Owner: ----
Labels: Type-Defect Priority-Medium Milestone-Release0.7.3 Evalf
New issue 3910 by asmeu...@gmail.com: Make is_constant smarter about mpmath
exceptions
http://code.google.com/p/sympy/issues/detail?id=3910
$ ./bin/test sympy/integrals/tests/test_integrals.py --seed 31507390
==================================================================== test
process starts
=====================================================================
executable: /sw/bin/python3 (3.3.2-final-0) [CPython]
architecture: 64-bit
cache: yes
ground types: gmpy 2.0.0
random seed: 31507390
hash randomization: on (PYTHONHASHSEED=270778785)
sympy/integrals/tests/test_integrals.py[93] .....fXff....w........................E......................................................
[FAIL]
_______________________________________________________________________
xpassed tests
________________________________________________________________________
sympy/integrals/tests/test_integrals.py: test_issue_1304_2
______________________________________________________________________________________________________________________________________________________________
__________________________________________
sympy/integrals/tests/test_integrals.py:test_integrate_returns_piecewise
__________________________________________
File "/users/aaronmeurer/documents/python/sympy/sympy/py3k-sympy/sympy/integrals/tests/test_integrals.py",
line 454, in test_integrate_returns_piecewise
assert integrate(x**(n*y), y) == Piecewise(
File "./sympy/utilities/decorator.py", line 30, in threaded_func
return func(expr, *args, **kwargs)
File "./sympy/integrals/integrals.py", line 1589, in integrate
return integral.doit(deep=False, meijerg=meijerg, conds=conds,
risch=risch)
File "./sympy/integrals/integrals.py", line 888, in doit
antideriv = self._eval_integral(function, xab[0], meijerg=meijerg1,
risch=risch, conds=conds)
File "./sympy/integrals/integrals.py", line 1129, in _eval_integral
result, i = risch_integrate(f, x, separate_integral=True, conds=conds)
File "./sympy/integrals/risch.py", line 1552, in risch_integrate
ans, i, b = integrate_hyperexponential(fa, fd, DE, conds=conds)
File "./sympy/integrals/risch.py", line 1315, in
integrate_hyperexponential
(qa.as_expr().subs(s) / qds, True)
File "./sympy/functions/elementary/piecewise.py", line 109, in __new__
r = cls.eval(*newargs)
File "./sympy/functions/elementary/piecewise.py", line 145, in eval
cond_eval = cls.__eval_cond(cond)
File "./sympy/functions/elementary/piecewise.py", line 492, in __eval_cond
if checksol(cond, {}, minimal=True):
File "./sympy/solvers/solvers.py", line 206, in checksol
if not val.is_constant(*list(sol.keys())):
File "./sympy/core/expr.py", line 530, in is_constant
b = self._random(None, -1, 0, 1, 0)
File "./sympy/core/expr.py", line 364, in _random
nmag = abs(self.evalf(2, subs=reps))
File "./sympy/core/evalf.py", line 1282, in evalf
result = evalf(self, prec + 4, options)
File "./sympy/core/evalf.py", line 1182, in evalf
r = rf(x, prec, options)
File "./sympy/core/evalf.py", line 496, in evalf_mul
arg = evalf(arg, prec, options)
File "./sympy/core/evalf.py", line 1182, in evalf
r = rf(x, prec, options)
File "./sympy/core/evalf.py", line 784, in evalf_log
re = mpf_log(mpf_add(xre, fone, prec2), prec, rnd)
File "./sympy/mpmath/libmp/libelefun.py", line 681, in mpf_log
raise ComplexResult("logarithm of a negative number")
sympy.mpmath.libmp.libmpf.ComplexResult: logarithm of a negative number
================== tests finished: 87 passed, 1 skipped, 3 expected to
fail, 1 expected to fail but passed, 1 exceptions, in 64.69 seconds
===================
DO *NOT* COMMIT!
The random seed is important. The issue is that is_constant evaluates at
random points, but it doesn't check for this mpmath exception.
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