iFit/lorz

 y = lorz(p, x, [y]) : Lorentzian

   iFunc/lorz Lorentzian fitting function
     y = p(1) ./ (1+ ((x-p(2)).^2/p(3)^2) ) + p(4);

   This expression assumes that the Amplitude is independent from the Width.

 lorz(width)          creates a model with a specified width
 lorz([ parameters ]) creates a model with specified model parameters

 Reference: http://en.wikipedia.org/wiki/Lorentzian_function

 input:  p: Lorentzian model parameters (double)
            p = [ Amplitude Centre HalfWidth BackGround ]
          or 'guess'
         x: axis (double)
         y: when values are given and p='guess', a guess of the parameters is performed (double)
 output: y: model value
 ex:     y=lorz([1 0 1 1], -10:10); or plot(lorz)

 Version: Aug. 22, 2017
 See also iFunc, iFunc/fits, iFunc/plot
 (c) E.Farhi, ILL. License: EUPL.