iFit/lognormal

 y = lognormal(p, x, [y]) : Log-Normal distribution function. 

   iFunc/lognormal Log-Normal distribution function. 
     y  = p(4)+ p(1)/sqrt(2)/p(3)./x .* exp( -log(x/p(2)).^2 /2/p(3)/p(3) )

 lognormal(centre)         creates a model with a specified centre
 lognormal([ parameters ]) creates a model with specified model parameters

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

 input:  p: Log-Normal model parameters (double)
            p = [ Amplitude Center Width 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=lognormal([1 0 1 1], -10:10); or plot(lognormal);

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