In the first, rotchain! function x was the variable, which respect we constructed the derivatives. It is like in a time dependent problem the t. As you move along the x axis, what shape the chain must have. So y is a function of x, y(x) = u[1] and dy/dx = u[2]. My main problem is exactly that I cannot, or I don’t know how to contain the time dependece in the rotchain! function. I tried to construct a different function for the rotation, rotation!, which is indeed a function of time.
So my main aim is that if I have a plot, it can be any plot, how can I make a 3d rotation of that plot around the y, or the upwards pointing axis?