symprod - error (again)

I am reposting this, as the person who was originally looking into this is on break. I am using the student version 7.12.0.365 of MATLAB.

The goal of the code below is to create a pre-specified number of vortices, denoted by the entries V(i). The vortices are in complex form (i.e. x+i*y etc). I would like to be able to take the symbolic product of the vortices (specified by the parameter vort_num).

For example: if I have 2 vortices V = [ x + y*i, x - 1 + y*i], then I would like psi_0 to be their symbolic product. The only problem is that I would like to be able to change the number of vortices easily, so I was trying to use the symprod function. This way I could easily expand from 2 vortices to 10,so on and so forth.

This is not working: I am getting the follow error:

??? Undefined function or method 'symprod' for input arguments of type 'sym'.

The code is:

    clc;
    clear;
    syms x y t k;

    vort_num = 2 %Set number of vortices

    A = ones(vort_num,3); %Construct a 3 row matrix consisting of each vortex parameter (A(row1),B(row2),E(row3))
    V = sym(ones(1,vort_num));

    for k = 1:vort_num
        A(k,3)=k-1 %Set displacement to be equal between each vortex, moving in the positive direction on the x-axis for each new vortex
        V(k) = A(k,1)*(x-A(k,3))+i*y*A(k,2) %Create complex form of each vortex
    end

    psi_0 = symprod(V(k), k, 1, vort_num); %Expand initial solution in polynomial form

I tried to change V to a symbolic matrix, but I am still having some issues.

Any help that you could provide could be extremely helpful.

Thanks Ima

[Andrew Newell]

That message about Walter's break is out of date. Rather than repost a question, edit your original question or add a comment so it jumps to the top of the queue.

[Walter Roberson]

The message is not out of date: our year-end is March 31 and I still have much to do.

[Andrew Newell]

How do you define "on a break"? You seem to be very active on this site still.