Status: New
Owner: ----
Labels: Type-Defect Priority-Medium
New issue 3724 by [email protected]: simplify raises IndexError: list
index out of range
http://code.google.com/p/sympy/issues/detail?id=3724
Hi,
(I'm assuming this is where I post information about what looks like a bug
sympy.)
I am tried to simplify an expression using simplify.
Here's something that worked:
In [266]: f = (-2*a*b - 2*alpha*t - 2*beta*t*x + 2*gamma*t)/(2 +
2*t*sigma**2)
In [267]: simplify(f)
Out[267]: (gamma*t - a*b - alpha*t - beta*t*x)/(1 + t*sigma**2)
Now, if I just include another variable in f, i.e. z, and then try to
simplify, I get the error below.
I can't see why this would happen, so I thought I would mention it here.
(note that z has been declared by from sympy.abc import z).
In [268]: f = (-2*a*b - 2*alpha*t - 2*beta*t*x + 2*gamma*t*z)/(2 +
2*t*sigma**2)
In [269]: simplify(f)
---------------------------------------------------------------------------
IndexError Traceback (most recent call last)
<ipython-input-269-553a780abe5d> in <module>()
----> 1 simplify(f)
/usr/lib/pymodules/python2.7/sympy/simplify/simplify.pyc in simplify(expr)
1309
1310 """
-> 1311 expr = Poly.cancel(powsimp(expr))
1312 expr = powsimp(together(expr.expand()), combine='exp',
deep=True)
1313 if expr.could_extract_minus_sign():
/usr/lib/pymodules/python2.7/sympy/polys/polynomial.pyc in cancel(f,
*symbols)
693 return numer / denom
694
--> 695 g = sympy.polys.algorithms.poly_gcd(p, q)
696
697 p = sympy.polys.algorithms.poly_div(p, g)[0]
/usr/lib/pymodules/python2.7/sympy/polys/algorithms.pyc in poly_gcd(f, g,
*symbols)
481
482 if f.is_multivariate:
--> 483 h = poly_div(f*g, poly_lcm(f, g))[0]
484 else:
485 h = poly_subresultants(f, g, res=False)[-1]
/usr/lib/pymodules/python2.7/sympy/polys/algorithms.pyc in poly_lcm(f, g,
*symbols)
410 h_coeffs = [ coeff*lcm for coeff in H[0].coeffs ]
411 else:
--> 412 h_coeffs = H[0].coeffs
413
414 h_monoms = [ monom[1:] for monom in H[0].monoms ]
IndexError: list index out of range
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