FFT filter - clean your signals and display results!

Perform Fourier transform, filter in frequency domain, reconstruct the signal.

The function introduces the implementation of fft and ifft in filtering and cleaning of signals.
The function plots
1. the original signal,
2. its transform,
3. the reconstructed (filtered) signal.
You can control the filtering by giving your parameters.
Comprehensive help is included (>>help fftf).
The code is extensively commented.