       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)

```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 + k

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?

```

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