summation of function

[Gaurav Dhingra]

Hi

Is this a bug ?

>>> from __future__ import division >>> from sympy import * >>> x, y, z, t = symbols('x y z t') >>> k, m, n = symbols('k m n', integer=True) >>> f, g, h = symbols('f g h', cls=Function) Documentation can be found at http://docs.sympy.org/0.7.6.

>>> summation(1/((k+3.5)*(k+8)), (k, 1, n))

Traceback (most recent call last): File "<string>", line 1, in <module> File "/base/data/home/apps/s~sympy-live-hrd/45.380685391411058699/sympy/sympy/concrete/summations.py", line 454, in summation return Sum(f, *symbols, **kwargs).doit(deep=False) File "/base/data/home/apps/s~sympy-live-hrd/45.380685391411058699/sympy/sympy/concrete/summations.py", line 169, in doit newf = eval_sum(f, (i, a, b)) File "/base/data/home/apps/s~sympy-live-hrd/45.380685391411058699/sympy/sympy/concrete/summations.py", line 559, in eval_sum value = eval_sum_symbolic(f.expand(), (i, a, b)) File "/base/data/home/apps/s~sympy-live-hrd/45.380685391411058699/sympy/sympy/concrete/summations.py", line 656, in eval_sum_symbolic return eval_sum_hyper(f_orig, (i, a, b)) File "/base/data/home/apps/s~sympy-live-hrd/45.380685391411058699/sympy/sympy/concrete/summations.py", line 725, in eval_sum_hyper res1 = _eval_sum_hyper(f, i, a) File "/base/data/home/apps/s~sympy-live-hrd/45.380685391411058699/sympy/sympy/concrete/summations.py", line 666, in _eval_sum_hyper return _eval_sum_hyper(f.subs(i, i + a), i, 0) File "/base/data/home/apps/s~sympy-live-hrd/45.380685391411058699/sympy/sympy/concrete/summations.py", line 705, in _eval_sum_hyper return f.subs(i, 0)*hyperexpand(h), h.convergence_statement File "/base/data/home/apps/s~sympy-live-hrd/45.380685391411058699/sympy/sympy/simplify/hyperexpand.py", line 2482, in hyperexpand return f.replace(hyper, do_replace).replace(meijerg, do_meijer) File "/base/data/home/apps/s~sympy-live-hrd/45.380685391411058699/sympy/sympy/core/basic.py", line 1351, in replace rv = bottom_up(self, rec_replace, atoms=True) File "/base/data/home/apps/s~sympy-live-hrd/45.380685391411058699/sympy/sympy/simplify/simplify.py", line 4082, in bottom_up rv = F(rv) File "/base/data/home/apps/s~sympy-live-hrd/45.380685391411058699/sympy/sympy/core/basic.py", line 1336, in rec_replace new = _value(expr, result) File "/base/data/home/apps/s~sympy-live-hrd/45.380685391411058699/sympy/sympy/core/basic.py", line 1280, in <lambda> _value = lambda expr, result: value(*expr.args) File "/base/data/home/apps/s~sympy-live-hrd/45.380685391411058699/sympy/sympy/simplify/hyperexpand.py", line 2471, in do_replace r = _hyperexpand(Hyper_Function(ap, bq), z, rewrite=rewrite) File "/base/data/home/apps/s~sympy-live-hrd/45.380685391411058699/sympy/sympy/simplify/hyperexpand.py", line 2052, in _hyperexpand formula = try_lerchphi(func) File "/base/data/home/apps/s~sympy-live-hrd/45.380685391411058699/sympy/sympy/simplify/hyperexpand.py", line 1793, in try_lerchphi part = apart(numer/denom, t) File "/base/data/home/apps/s~sympy-live-hrd/45.380685391411058699/sympy/sympy/utilities/decorator.py", line 35, in threaded_func return func(expr, *args, **kwargs) File "/base/data/home/apps/s~sympy-live-hrd/45.380685391411058699/sympy/sympy/polys/partfrac.py", line 86, in apart raise PolynomialError(msg) PolynomialError: RisingFactorial(_t + 1, 8.0) contains an element of the generators set

[Sergey Kirpichev]

On Wednesday, January 14, 2015 at 12:56:40 PM UTC+3, Gaurav Dhingra wrote:

Hi

Is this a bug ?

Sure, it's.

https://github.com/sympy/sympy/issues/8822

Sympy's bugtracker is here:
https://github.com/sympy/sympy/issues/