I'm developing 2d frame stiffness analysis.. im on the the final stage.. how to solve "This value must be an interger".. this will appear when i try to input the member force to excel component.

i is a range variable, so you can display memf(i)[1, but if you want to assign the results to a variable then the inedexing must also appear on the LHS of the assignment. So X:=memf(i)[i will give you the same error, but X[i:-memf(i)[1 will create a vector, X, that contains the results. I don't think there's any way to do that directly in the Excel component (but I'm doing something in Excel right now that prevents me from trying it, so I am not sure of that), so you will have to create vectors that contain the desired results, and then use those vectors in the Excel component.