Status: Accepted
Owner: ----
Labels: Type-Defect Priority-Medium Series Simplify
New issue 3040 by asmeu...@gmail.com: Problem with simplify() with an
expression with O()
http://code.google.com/p/sympy/issues/detail?id=3040
In [282]: simplify(collect((a/(x - alpha)).subs(alpha, (1 + sqrt(5))/2 +
alpha1*x + alpha2*x**2 + alpha**3*x**3).series(x, 0, 4), x))
---------------------------------------------------------------------------
NonCommutativeExpression Traceback (most recent call last)
/Users/aaronmeurer/Documents/Python/sympy/sympy/<ipython-input-282-c34bd6241175>
in
<module>()
----> 1 simplify(collect((a/(x - alpha)).subs(alpha, (1 + sqrt(5))/2 +
alpha1*x + alpha2*x**2 + alpha**3*x**3).series(x, 0, 4), x))
/Users/aaronmeurer/Documents/Python/sympy/sympy/sympy/simplify/simplify.pyc
in simplify(expr, ratio, measure)
2696
2697 expr1 = cancel(powsimp(expr))
-> 2698 expr2 = together(expr1.expand(), deep=True)
2699 if ratio is S.Infinity:
2700 expr = expr2
/Users/aaronmeurer/Documents/Python/sympy/sympy/sympy/polys/rationaltools.pyc
in
together(expr, deep)
81 return expr
82
---> 83 return _together(sympify(expr))
/Users/aaronmeurer/Documents/Python/sympy/sympy/sympy/polys/rationaltools.pyc
in
_together(expr)
64 return expr
65 elif expr.is_Add:
---> 66 return gcd_terms(map(_together,
Add.make_args(expr)))
67 elif expr.is_Pow:
68 base = _together(expr.base)
/Users/aaronmeurer/Documents/Python/sympy/sympy/sympy/core/exprtools.pyc in
gcd_terms(terms, isprimitive)
395 isexpr = isinstance(terms, Expr)
396 if not isexpr or terms.is_Add:
--> 397 cont, numer, denom = _gcd_terms(terms, isprimitive)
398 coeff, factors = cont.as_coeff_Mul()
399 return _keep_coeff(coeff, factors*numer/denom)
/Users/aaronmeurer/Documents/Python/sympy/sympy/sympy/core/exprtools.pyc in
_gcd_terms(terms, isprimitive)
348 return terms[0], S.One, S.One
349
--> 350 terms = map(Term, terms)
351 cont = terms[0]
352
/Users/aaronmeurer/Documents/Python/sympy/sympy/sympy/core/exprtools.pyc in
__init__(self, term, numer, denom)
233 if numer is None and denom is None:
234 if not term.is_commutative:
--> 235 raise NonCommutativeExpression('commutative
expression expected')
236
237 coeff, factors = term.as_coeff_mul()
NonCommutativeExpression: commutative expression expected
In [283]: simplify(collect((a/(x - alpha)).subs(alpha, (1 + sqrt(5))/2 +
alpha1*x + alpha2*x**2 + alpha**3*x**3).series(x, 0, 4), x).removeO())
___
3 ╲╱ 5 2 2 3 3
- ─ - α₁⋅x - ───── + x - α₂⋅x - α ⋅x
2 2
In [284]: print a
alpha**2 - alpha*x**2 + alpha + x**3 - x*(alpha + 1)
Sorry for the complex example. I don't have time to simplify it.
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