iFit/bose

 y = bose(p, x, [y]) : Bose

   iFunc/bose Bose fitting function
     n(x) = 1 ./ (exp(x/p(1)) - 1);
     y = n(x)+1 for x > 0
     y = n(x)   for x < 0

 The Bose factor has the sign of x.
   (n+1) converges to 0 for x -> -Inf, and to 1 for x-> +Inf. It diverges at x=0.
   n(x)+n(-x) = -1
         
 When 'x' is an energy in meV, the parameter p should be T/11.6045

 Reference: http://en.wikipedia.org/wiki/Bose-Einstein_statistics

 input:  p: Bose model parameters (double)
            p = [ Kb.T/hbar   in 'x' units ]
          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=bose(300/11.605, -10:10); or y=plot(bose);

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