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is there any definite method or algorithm,software to get exact function or expression from series.e.g we get series solution of differential equation and we want exact expression rather than approximation series ?

flag	asked Sep 10 2011 at 16:22 anksh 13●2

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Usually I do this the other way around. I have a power series, and want its sum, so if I can find a DE it satisfies, then solve the DE to get the result! – Gerald Edgar Sep 11 2011 at 12:50

Igor Rivin · Accepted Answer · 2011-09-11 18:26:06Z UTC

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In some cases yes, see:

http://www.reduce-algebra.com/docs/qsum.pdf

and references therein...

EDIT A canonical reference is Petkovsek-Zeiberger's A=B.

edited Sep 11 2011 at 18:26

answered Sep 10 2011 at 18:42

Igor Rivin
31.1k●3●37●71

	thanks very much, i would like to see more such stuff – anksh Sep 11 2011 at 6:41
	More stuff in Wilf's book generatingfunctionology – Gerald Edgar Sep 11 2011 at 12:49

method for getting function from power series/perturbation series

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