%
%   HW14_DEMO1_EQN.M   Function file for solution of HW14_DEMO1
%
%   This file simply evaluates zp = f(t,z) for the input t and z values.  In this
%   problem, f(t,z) and z are 2-element vectors. 
%       z1 --> position  and  z2 --> velocity
%
%   File prepared by J. R. White, UMass-Lowell (April 2005)
%
      function zp = eqnfile(t,z)
      zp = zeros(size(z));
      zp(1) = z(2);
      zp(2) = -13*z(1) - 6*z(2) + 10*sin(5*t);
%
%   end of function