How to get power spectrum plot from time series data?

I have been trying to plot power spectrum of chaotic model-system from time series data. I have saved the time series data in a .mat file. Please tell me what should I do next to get that plot.

[dpb]

See

doc fft  % example for PSD by FFT

Alternatively, if have Signal Processing TB, there are several alternative methods provided...try

lookfor psd

to see what is installed on your system...