Re: Symbolic summation
- To: mathgroup at smc.vnet.net
- Subject: [mg101591] Re: [mg101561] Symbolic summation
- From: Bob Hanlon <hanlonr at cox.net>
- Date: Fri, 10 Jul 2009 23:21:39 -0400 (EDT)
- Reply-to: hanlonr at cox.net
n = 3;
Sum[ToExpression["k" <> ToString[m]], {m, 2, n}]
k2+k3
However, it is much easier and cleaner to use the form k[m]
Sum[k[m], {m, 2, n}]
k[2] + k[3]
Bob Hanlon
---- Luca <Lucazanottifragonara at alice.it> wrote:
=============
Hello all, I have a problem, I've to compute a symbolic summation, which takes a very long time if I have to do it by hand. I have to write the terms of the Volterra series, related to the associated linear equation of a system.
The problem is that I'm not really confident with mathematica, I've tried to use symbolic calculations with sums, but I think that in my case is not so easy.
The problem is that I want a solution of this form:
x1+x2+x3+x4+x5...
Where the 1, 2, 3 and 4 and 5 are the summation subscripts...
My summation is not infinite, I have to stop it.
If I write something like this:
n = 3;
Sum[kl, {l, 2, n}]
I obtain 2kl, instead I want to obtain k2+k3.
Is it possible with mathematica?