function yprime = nndhop(t,y)
%NNDHOP Calculates the derivative for Hopfield network
%
%	NNDHOP(t,y)
%	  t - Current time
%	  y - Current output
%	Returns dy.

global lambda;
global W;
global b;

a = 2/pi*atan(lambda*pi*y*0.5);
yprime = -y+W*a+b;