iFit/gauss

 y = gauss(p, x, [y]) : Gaussian

   iFunc/gauss Gaussian fitting function
     y = p(1)*exp(-0.5*((x-p(2))/p(3)).^2) + p(4);

   The HalfWidth parameter is the Gaussian square root variance (Sigma). 
   The 'true' half width is thus 1.177*HalfWidth.

 gauss(width)          creates a model with a specified width(sigma)
 gauss([ parameters ]) creates a model with specified model parameters

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

 input:  p: Gaussian 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=gauss([1 0 1 1], -10:10); or plot(gauss)

 Version: Aug. 22, 2017
 See also iFunc, iFunc/fits, iFunc/plot, gauss1, lorz
 (c) E.Farhi, ILL. License: EUPL.