Bill Allombert on Fri, 03 Jun 2011 20:11:33 +0200

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Re: Multiple Summation Question

On Fri, Jun 03, 2011 at 05:19:22PM +0000, McLaughlin, James wrote:
> Thanks to Karim and Hauke for their suggestions. I will try to make them work (I am a very basic programmer in pari).
> I may have mis-stated the problem, or maybe over simplified it by stating the example I gave, so here is another attempt to describe in more detail is what i hope to do.
> Suppose 
> F(k)=Sum_{j_1=1}^1 Sum_{j_2=1}^2 ... Sum_{j_k=1}^k Product_{i=1}^k f_i (j_1,j_2, ..., j_i, other parameters)
> each f_i has a similar form, say
>  f_i (j_1,j_2, ..., j_i, other parameters)
>  = 1+ j_1*j_2*...*j_i + q^(i*j_i - (i-1)*j_{i-1}) + a_1*a_2*...*a_i/a_{k-i+1}.
> (q and a_1, a_2, ...  are previously defined values).

Well, you can start by defining a function f that takes i, [j_1,...,j_k] and the other parameters
and returns f_i (j_1,j_2, ..., j_i, other parameters).

At this point you should be able to finish with forvec.