function  Z =sigmoid0(Y)
%
%       function  Y  = SIGMOID(X)
%
%       This function represents the saturating properties of the cochlear amplifier
%       It has the shape of an  asymmetric sigmoid, with slope 1 at  X = 0 and
%       maxY - minY = 0.1.
%
%     〤opyright by Renato Nobili, Padova University, Italy, 2003 - Not for commercial use.


y1=0.1139;
y2=0.3736;
c1=0.7293;
c2=1.4974;
b=0.30991;
Z=(1./(1+c1*exp(-Y./y1)+c2*exp(-Y./y2)))-b;