Recursion problem in SymbolicSum
- To: mathgroup at smc.vnet.net
- Subject: [mg60693] Recursion problem in SymbolicSum
- From: djw1005 at cus.cam.ac.uk (D.J. Wischik)
- Date: Sat, 24 Sep 2005 02:55:35 -0400 (EDT)
- Organization: University of Cambridge, England
- Sender: owner-wri-mathgroup at wolfram.com
I was surprised to get problems (recursion limit exceeded) when executing
a symbolic sum. The terms in the sum depend on a parameter mu. When I
leave mu unspecified and calculate the sum and then substitute a numerical
value for mu, I get the right answer. When I specify mu in the sum, the
symbolic sum fails. (The sum definitely exists and is finite.) I would be
grateful if anyone could explain this behaviour.
PoissonProb[mu_, k_] = Exp[-mu] mu^k / k!;
Sum[PoissonProb[mu, k] (k + 1 - 9)/(k + 1), {k, 9, Infinity}] /.
{mu -> 1.05}
[returns the answer 1.82353 * 10^(-7) as expected]
Sum[PoissonProb[1.05, k](k + 1 - 9)/(k + 1), {k, 9, Infinity}]
[ $RecursionLimit::reclim: Recursion depth of 256 exceeded.
$IterationLimit::itlim: Iteration limit of 4096 exceeded.
and then it returns the following. ]
\!\(0.34993774911115527`\ \((4.298654386611213`*^-6 -
7.999999999999789`\ \
Hold[If[MatchQ[Numerator[SymbolicSum`InfiniteDump`expr1$214],
SymbolicSum`a$_ \
+ SymbolicSum`b$_ /; \(!
FreeQ[SymbolicSum`a$,
K$94]\) && \(! FreeQ[SymbolicSum`b$, K$94]\)], \
\((SymbolicSum`InfiniteDump`infinitesum[#1, K$94, 0] &)\) /@
Expand[SymbolicSum`InfiniteDump`expr1$214],
SymbolicSum`InfiniteDump`HypergeometricSeries[
1, SymbolicSum`InfiniteDump`expr1$214, \
SymbolicSum`InfiniteDump`expr2$214, K$94, 0, SymbolicSum`eps$214]]])\)\)
Damon.
- Follow-Ups:
- Re: Recursion problem in SymbolicSum
- From: Devendra Kapadia <dkapadia@wolfram.com>
- Re: Recursion problem in SymbolicSum
- From: Pratik Desai <pdesai1@umbc.edu>
- Re: Recursion problem in SymbolicSum
- From: <bsyehuda@gmail.com>
- Re: Recursion problem in SymbolicSum