Re: Symbolic summation

• To: mathgroup at smc.vnet.net
• Subject: [mg101605] Re: [mg101561] Symbolic summation
• From: Sseziwa Mukasa <mukasa at jeol.com>
• Date: Fri, 10 Jul 2009 23:24:11 -0400 (EDT)
• References: <200907101044.GAA15502@smc.vnet.net>

```On Jul 10, 2009, at 6:44 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?

Yes

n=3
Sum[k[l],{l,2,n}]

It's not easy to work with subscripts explicitly in Mathematica, it's
better to work with function arguments.

Regards,

Sseziwa

```

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