Status: Valid
Owner: ----
Labels: Type-Defect Priority-Medium Solvers

New issue 3258 by [email protected]: AssertionError in dsolve()
http://code.google.com/p/sympy/issues/detail?id=3258

In [172]: dsolve(-b1(x) - (x - xp)*b1(x).diff(x) + q(x), b1(x))
---------------------------------------------------------------------------
AssertionError                            Traceback (most recent call last)
/Users/aaronmeurer/Documents/Python/sympy/sympy/<ipython-input-172-5bebda334e1e> in <module>()
----> 1 dsolve(-b1(x) - (x - xp)*b1(x).diff(x) + q(x), b1(x))

/Users/aaronmeurer/Documents/Python/sympy/sympy/sympy/solvers/ode.pyc in dsolve(eq, func, hint, simplify, prep, **kwargs) 531 return dsolve(eq, func, hint=hints['default'], simplify=simplify, 532 prep=prep, classify=False, order=hints['order'],
--> 533                       match=hints[hints['default']])
    534     elif hint in ('all', 'all_Integral', 'best'):
    535         retdict = {}

/Users/aaronmeurer/Documents/Python/sympy/sympy/sympy/solvers/ode.pyc in dsolve(eq, func, hint, simplify, prep, **kwargs)
    575     if simplify:
    576         rv = odesimp(solvefunc(eq, func, order=hints['order'],
--> 577             match=hints[hint]), func, hints['order'], hint)
    578     else:
579 # We still want to integrate (you can disable it separately with the hint)

/Users/aaronmeurer/Documents/Python/sympy/sympy/sympy/core/multidimensional.pyc in wrapper(*args, **kwargs) 123 result = apply_on_element(wrapper, args, kwargs, n)
    124                     return result
--> 125             return f(*args, **kwargs)
    126         return wrapper

/Users/aaronmeurer/Documents/Python/sympy/sympy/sympy/solvers/ode.pyc in odesimp(eq, func, order, hint)
    973
    974     # First, integrate if the hint allows it.
--> 975     eq = _handle_Integral(eq, func, order, hint)
    976     assert isinstance(eq, Equality)
    977

/Users/aaronmeurer/Documents/Python/sympy/sympy/sympy/solvers/ode.pyc in _handle_Integral(expr, func, order, hint)
   1729             if not i.has(x0) and not i.has(y0):
   1730                 sol += i
-> 1731         assert sol != 0
   1732         sol = Eq(sol.subs(y, f(x)),expr.rhs) # expr.rhs == C1
   1733         del exactvars

AssertionError:

This is using the default hint, '1st_exact'.  Perhaps issue 2793 would help here.

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