I finalized SLsimPPC. The code creates a Probabilistic Population Code that
%            encodes motion directions (e.g., a space of feature)
%            in neural tuning responses, implicitly encodes likelihood of all moti   %            on directions and readout the input motion direction.
%
%     usage:
%
%           output = SLsimPPC(70,20,200,'display=on')
%           output = SLsimPPC(70,100,200,'display=on')
%
%Description:
%
%   - A population of N neurons with tuning curves responses
%     to motion direction
%
%   - Tuning curves are von Mises
%     fi(direction) =  Gain*von mises + base firing;
%
%   - Neurons have preferred directions between 0 and 360º.
%
%   - Spike count has Poisson variability.
%
%
%%references:
%
%    http://homepages.inf.ed.ac.uk/pseries/CCN14/lab4.pdf
%    Jazayeri et al,2006, Nat.Neu
%    Ma et al,2006, Nat.Neu