Dear Ali

You have to elaborate you question a little more. You want Basis for FEM

I think what you want is given four points in 3D, how to find the basis for the space.

Hi

3D BASIS analyze the base isolated structures assuming the superstructure to be linear and updates the nonlinear forces in the isolation system by the semi-implicit Runge-Kutta method. What I really need is the algorithm of the semi-implicit Runge-Kutta method. I have the 4th order Runge-Kutta but I could not find the algorithm for the semi-implicit Runge-Kutta.

I would really appreciate if somebody could help.

Thanks