Status: Valid
Owner: ----
Labels: Type-Defect Priority-Medium
New issue 3793 by [email protected]: Integrate hangs
http://code.google.com/p/sympy/issues/detail?id=3793
Try this:
from sympy import var, integrate, pi, sin, S
var("x y z c L")
f = 12*pi**2*L**2*c**2*sin(pi*(2*L*c*x - c + S(1)/2))**2*sin(pi*(2*L*c*y -
c + S(1)/2))**2*sin(pi*(2*L*c*z - c + S(1)/2))**2
i = integrate(f, (x, 0, L), (y, 0, L), (y, 0, L))
The integrate command "hangs" (probably just takes forever). But the
structure of this expression really isn't that complicated, so I am not
quite sure what is happening.
It hangs here when I hit ctrl-C:
Traceback (most recent call last):
File "a.py", line 4, in <module>
i = integrate(f, (x, 0, L), (y, 0, L), (y, 0, L))
File "/nh/nest/u/ondrej/repos/python-hpcmp2/local/lib/python2.7/site-packages/sympy/utilities/decorator.py",
line 25, in threaded_func
return func(expr, *args, **kwargs)
File "/nh/nest/u/ondrej/repos/python-hpcmp2/local/lib/python2.7/site-packages/sympy/integrals/integrals.py",
line 1360, in integrate
return integral.doit(deep = False, meijerg = meijerg, conds = conds)
File "/nh/nest/u/ondrej/repos/python-hpcmp2/local/lib/python2.7/site-packages/sympy/integrals/integrals.py",
line 734, in doit
antideriv = self._eval_integral(function, xab[0], meijerg1)
File "/nh/nest/u/ondrej/repos/python-hpcmp2/local/lib/python2.7/site-packages/sympy/integrals/integrals.py",
line 998, in _eval_integral
h = heurisch(g, x, hints=[])
File "/nh/nest/u/ondrej/repos/python-hpcmp2/local/lib/python2.7/site-packages/sympy/integrals/risch.py",
line 459, in heurisch
result = heurisch(f, x, mappings=mappings, rewrite=rewrite,
hints=hints, retries=retries-1)
File "/nh/nest/u/ondrej/repos/python-hpcmp2/local/lib/python2.7/site-packages/sympy/integrals/risch.py",
line 459, in heurisch
result = heurisch(f, x, mappings=mappings, rewrite=rewrite,
hints=hints, retries=retries-1)
File "/nh/nest/u/ondrej/repos/python-hpcmp2/local/lib/python2.7/site-packages/sympy/integrals/risch.py",
line 276, in heurisch
result = heurisch(f, x, rewrite=True, hints=hints)
File "/nh/nest/u/ondrej/repos/python-hpcmp2/local/lib/python2.7/site-packages/sympy/integrals/risch.py",
line 434, in heurisch
result = _integrate('Q')
File "/nh/nest/u/ondrej/repos/python-hpcmp2/local/lib/python2.7/site-packages/sympy/integrals/risch.py",
line 429, in _integrate
solution = solve(equations.values(), *coeffs)
File "/nh/nest/u/ondrej/repos/python-hpcmp2/local/lib/python2.7/site-packages/sympy/solvers/solvers.py",
line 782, in solve
solution = _solve_system(f, symbols, **flags)
File "/nh/nest/u/ondrej/repos/python-hpcmp2/local/lib/python2.7/site-packages/sympy/solvers/solvers.py",
line 1275, in _solve_system
result = solve_linear_system(matrix, *symbols, **flags)
File "/nh/nest/u/ondrej/repos/python-hpcmp2/local/lib/python2.7/site-packages/sympy/solvers/solvers.py",
line 1684, in solve_linear_system
matrix.row(k, lambda x, j: simplify(x - matrix[i, j]*coeff))
File "/nh/nest/u/ondrej/repos/python-hpcmp2/local/lib/python2.7/site-packages/sympy/matrices/matrices.py",
line 3680, in row
self[i, j] = f(self[i, j], j)
File "/nh/nest/u/ondrej/repos/python-hpcmp2/local/lib/python2.7/site-packages/sympy/solvers/solvers.py",
line 1684, in <lambda>
matrix.row(k, lambda x, j: simplify(x - matrix[i, j]*coeff))
File "/nh/nest/u/ondrej/repos/python-hpcmp2/local/lib/python2.7/site-packages/sympy/simplify/simplify.py",
line 2911, in simplify
expr1 = cancel(expr0)
File "/nh/nest/u/ondrej/repos/python-hpcmp2/local/lib/python2.7/site-packages/sympy/polys/polytools.py",
line 5563, in cancel
c, P, Q = F.cancel(G)
File "/nh/nest/u/ondrej/repos/python-hpcmp2/local/lib/python2.7/site-packages/sympy/polys/polytools.py",
line 3178, in cancel
result = F.cancel(G, include=include)
File "/nh/nest/u/ondrej/repos/python-hpcmp2/local/lib/python2.7/site-packages/sympy/polys/polyclasses.py",
line 649, in cancel
cF, cG, F, G = dmp_cancel(F, G, lev, dom, include=False)
File "/nh/nest/u/ondrej/repos/python-hpcmp2/local/lib/python2.7/site-packages/sympy/polys/euclidtools.py",
line 1884, in dmp_cancel
_, p, q = dmp_inner_gcd(f, g, u, K)
File "/nh/nest/u/ondrej/repos/python-hpcmp2/local/lib/python2.7/site-packages/sympy/polys/euclidtools.py",
line 1587, in dmp_inner_gcd
J, (f, g) = dmp_multi_deflate((f, g), u, K)
File "/nh/nest/u/ondrej/repos/python-hpcmp2/local/lib/python2.7/site-packages/sympy/polys/densebasic.py",
line 1356, in dmp_multi_deflate
B[i] = igcd(B[i], m)
File "/nh/nest/u/ondrej/repos/python-hpcmp2/local/lib/python2.7/site-packages/sympy/core/numbers.py",
line 93, in igcd
return _gcdcache[(a,b)]
KeyboardInterrupt
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