function varargout = kepler_f(E)%% %%  [y]    = kepler(E)  returns the function value y= M - E + e sin(E),%  [y,yp] = kepler(E)  returns the function value in y and %                       the derivative in yp%%  Matthias Heinkenschloss%  Department of Computational and Applied Mathematics%  Rice University%  March 29, 2001%M = 1;e = 0.5;% return the function valuevarargout{1} = M - E + e*sin(E);if( nargout > 1 )  % return the derivative as the second argument  varargout{2} = -1 + e*cos(E);end