Re: Symbolic summation

• To: mathgroup at smc.vnet.net
• Subject: [mg101631] Re: [mg101561] Symbolic summation
• From: Louis Talman <talmanl at gmail.com>
• Date: Sun, 12 Jul 2009 05:48:22 -0400 (EDT)
• References: <200907101044.GAA15502@smc.vnet.net>

```Sum[ToExpression["k" <> ToString[l]], {l, 1, 5}]

will do what you say you want.  But

Sum[k[l], {l, 1, 5}]

is a better thing to want.

--Lou Talman
Department of Mathematical & Computer Sciences
Metropolitan State College of Denver

<http://clem.mscd.edu/%7Etalmanl>

On Jul 10, 2009, at 4:44 AM, Luca 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?
>

--Lou Talman
Department of Mathematical & Computer Sciences
Metropolitan State College of Denver

<http://clem.mscd.edu/%7Etalmanl>

```

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