Status: Accepted
Owner: ----
Labels: Type-Enhancement Priority-Medium Solvers
New issue 3160 by [email protected]: dsolve() solve to handle "derivative
factored" equations
http://code.google.com/p/sympy/issues/detail?id=3160
In [134]: dsolve(Derivative(f(x)*x, x, x, x), f(x))
---------------------------------------------------------------------------
NotImplementedError Traceback (most recent call last)
/Users/aaronmeurer/Documents/Python/sympy/sympy/<ipython-input-134-f7ca24621453>
in
<module>()
----> 1 dsolve(Derivative(f(x)*x, x, x, x), f(x))
/Users/aaronmeurer/Documents/Python/sympy/sympy/sympy/solvers/ode.py in
dsolve(eq, func, hint, simplify, prep, **kwargs)
525 if not hints['default']:
526 # classify_ode will set hints['default'] to None if no
hints match.
--> 527 raise NotImplementedError("dsolve: Cannot solve " + str(eq))
528
529 if hint == 'default':
NotImplementedError: dsolve: Cannot solve x*Derivative(f(x), x, x, x) +
3*Derivative(f(x), x, x)
But since the ode is explicitly given in a derivative factored form, it's
easy to solve (just integrate three times. There are also ways to
recognize expressions of this form even when they are expanded (i.e., exact
equations), so we can add better support for those too.
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