How matlab does its fast Fourier transform.

Click here to down-load a diary that shows how fft and ifft work.
a *.ps file that demonstrate where aliasing error comes from.
another *.ps file that demonstrate where aliasing error comes from.

Click here to down-load find_spec.m, a routine that takes a vector and returns its power spectrum.

This (heat4.m) solves the heat equation with explicit time-stepping, and spectrally-computed space derivatives. A diary where heat4.m is used.

This (heat5.m) solves the heat equation with implicit time-stepping, and spectrally-computed space derivatives.