       Re: Symbolic summation

• To: mathgroup at smc.vnet.net
• Subject: [mg101617] Re: Symbolic summation
• From: Armand Tamzarian <mike.honeychurch at gmail.com>
• Date: Fri, 10 Jul 2009 23:26:21 -0400 (EDT)
• References: <h3761n\$f3i\$1@smc.vnet.net>

```On Jul 10, 5:44 am, Luca <Lucazanottifragon... 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 term=
s of the Volterra series, related to the associated linear equation of a sy=
stem.
>
> 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?

Sum[ToExpression[ToString[k] <> ToString[i]], {i, 1, 5}]

Mike

```

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