%
%   SF_DEMO3_EQN.M   Function file for SF_DEMO3.M
%
%   This file simply evaluates yp = f(x,y) for the input x and y values.
%   Called as part of solution for plotting slope fields and solution curves.
%
%   File prepared by J. R. White, UMass-Lowell (Feb. 2005)
%
      function yp = eqnfile(x,y)
      yp = x.*x - y.*y;
%
%   end of function
