This value mast be a vector

You should create a discussion/question, not a blog, to get help.

Nobody would be able to add a corrected worksheet in a blog comment.

try adding x[N=0 between the N=rows() and the for loop.

(= should be the back arrow)

until you have an array x you cannot calculate the summation of x*U

Regards

   Andy

did work in xmcd Andy?

When you create x[N-1 the summation requires x[N, which you have not defined. Andy suggests setting it to 0. That certainly makes the calcuation work, but you will have to decide what value x[N should actually be set to.

Thanks Richard