LabVIEW
Loop
Solved!
Apparently your only confusion is with statement 50, so I must assume that the rest is mostly in place already. Can you post your Vi (i.e. what you have so far) so we can better see what needs to be done to complete it.
Also remember that loops and array indices in LabVIEW are zero based, so account for that when dealing with iterations and indices.
Here is what I was thinking about the first part of your computation (up to computing Presa2):
Notice that Q and F are "wires", and X lives "mostly in the wire". The way you index C suggests that it is really a 3D array (though its size seems wrong, but you index it as though it had a 2D array "played out in row-major order") -- if you define/create it as such, using it will be much easier.
Your final computation of Presa2 introduces a bit of "magic" called Recursion. You are basically evaluating a polynomial. If I write the polynomial in the form a0 + a1 * x^1 + a2 * x^2 + ..., and make the coefficients into an array [a0, a1, ...], consider the following function:
- f[empty array, x] = 0.
- f[non-empty array, x] = first element of array + f[rest-of-the-array] * x
I claim that f[array, x] is the function you want.
Suppose you only have a0. f[a0] (by the second rule) = a0 + f[empty array, x] = a0. OK so far.
Now how about [a0, a1]? f[a0, a1] = a0 + f[a1, x] = a0 + a1*x. I'll let you work out f[a0, a1, a2] for yourself.
Not every programming language supports Recursion (I don't believe that Fortran does). LabVIEW does, but you need to learn about sub-VIs, then you need to learn about re-entrant sub-VIs, a little more advanced, perhaps, than you are ready for.
There are ways to implement recursion using other means, but they tend to be a little clumsy, kind of like writing out the formula for Presa2 that you have in your Fortran code.
Bob Schor
