I need help with a program in MatLab. I have developed that solves systems of differential equations.

The equation of motion is formulated as:

[m] x”+[c] x’ +[k]x = Force

I have a code that solves this system of equation in terms of x (displacement) vs time. The system is nonlinear. I’ve attached the codes. It gives me the graph of displacement vs time. However, I also need the response for acceleration and speed vs time. I would also like the response in frequency domain (Fourier Transform).

Finally, the force that is being used is a sinusoidal force, I would like to exchange it for the acceleration of an earthquake (El centro – Notepad file) plus the white noise (easily found on the internet). (I have a clue on how to do it, but I do not have time. So, if you have any question, feel free to ask me).

Thanks in advance!