question about shooting method

[krwlz101]

I am working on modeling the resonse of a spring mass damper system to a variety of periodic inputs.  As a result, I am learning how to solve differential equations using labview.

I am currently using the the example vi "Shooting Method" as a guide.  I had a simple question, and wondered if any could answer it.

In the bottom of the Runge Kutta vi, why is the RHS of the equation built into an array with string variable y?  Is this the method that vi uses to determine that y is the first differential of the x equation?

[Darin.K]

For this VI you input a series of equations:  x1' = f1(x1,x2,..,t), x2' = f2(x1,x2,...,t) and so on.

the array [x,y] tells you that x1 = x, x2 = y

If you look at the equations:  x'=y, y'=f(x,y,t) you see that the first element is x' which equals y.

A long way of saying, that your answer is correct.  Hopefully you now know why it is correct. 

[krwlz101]

I think that I understand, and thanks for the explanation.  It has been a long time since I did diff eq, and making the computer do it is not any easier.