function yprime = nndpend(t,y)
%NNDPEND Dynamical model of a pendulum.
%	
%	NNDPEND(T,Y)
%	  T - Time
%	  Y - State = [angle; angular velocity]
%   Returns Derivative of state vector.

% First Version, 8-31-95.

%==================================================================

yprime(1) = y(2);
yprime(2) = -sin(y(1)) - 0.2*y(2);