Dear Andrea Marisotti,

You can try to require it to the manifacturer of VNAs (Agilent Technolgies or Keysight, Rohde & Schwarz, Anritsu, etc.). However, I think that they do not release their codes. Therefore, I think that you must make your code starting from the  measurements in frequency domain.

Dear Andrea,

you might find this interesting:

http://scikit-rf-web.readthedocs.org

It is Phyton, not Matlab, but might be close to what you are looking for.

Martin

@Angelo. It is what I am doing at the moment, but never like to reinvent the wheel! However, not only codes are not disclosed, but papers and manuals dealing with them are rarely clear and sharp to the target; they rather use ambiguous terms, such as when talking about direct frequency-domain processing of data to perform time-gating: they use a filter, it is designed only in case of Kaiser-Bessel window, but such design is subject to heavy constraints on length (number of taps) and roll-off, and this is not mentioned .. so probably implementation is in reality different. (this is just one example)

@Martin. Thanks! having a look at it, Python and Matlab, come on, are interchangeable, and my concern was mainly -- as said above -- not to reinvent the wheel. I want to show useful code in a book I'm writing and that I'm going to release soon. This is the last effort, that I have kept as the last one, waiting for something to ripe in the meanwhile.