Comment #11 on issue 2132 by asmeurer: Derivative of RootSum
http://code.google.com/p/sympy/issues/detail?id=2132
I just noticed, don't you have x and z backwards in that example (c.f. the
output from integrate in [29] in my OP)? It should be RootSum(z**5 - z**2
+ 1, Lambda(z, z*log(x - z))). If I use that, I get:
In [52]: a = RootSum(z**5 - z**2 + 1, Lambda(z, z*log(x - z)))
In [53]: a.diff(x)
Out[53]:
34
- ──
21
In [54]: a.diff(z)
---------------------------------------------------------------------------
ValueError Traceback (most recent call last)
/Users/aaronmeurer/Documents/Python/sympy/sympy/<ipython console> in
<module>()
/Users/aaronmeurer/Documents/Python/sympy/sympy/sympy/core/expr.py in
diff(self, *symbols, **assumptions)
834 x = sympify(x)
835 c,e = self.as_leading_term(x).as_coeff_exponent(x)
--> 836 c = powsimp(c, deep=True, combine='exp')
837 if not c.has(x):
838 return c,e
/Users/aaronmeurer/Documents/Python/sympy/sympy/sympy/core/function.py in
__new__(cls, expr, *symbols, **assumptions)
583 if not expr.has(s):
584 return S.Zero
--> 585 obj = expr._eval_derivative(s)
586 if obj is None:
587 unevaluated_symbols.append(s)
/Users/aaronmeurer/Documents/Python/sympy/sympy/sympy/polys/rootoftools.py
in _eval_derivative(self, x)
482 if hints.get('roots', True):
483 return Add(*map(self.func, self.roots))
484 else:
485 return self
486
/Users/aaronmeurer/Documents/Python/sympy/sympy/sympy/polys/rootoftools.py
in new(cls, poly, func)
482 if hints.get('roots', True):
483 return Add(*map(self.func, self.roots))
484 else:
485 return self
486
/Users/aaronmeurer/Documents/Python/sympy/sympy/sympy/polys/rootoftools.py
in _rational_case(cls, poly, func)
482 if hints.get('roots', True):
483 return Add(*map(self.func, self.roots))
484 else:
485 return self
486
ValueError: need more than 0 values to unpack
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