% 
% Written by:
% -- 
% John L. Weatherwax, Ph.D.         2002-11-05
% MIT Lincoln Laboratory
% 244 Wood Street
% Lexington, MA 02420-9176 USA
% 
% email: weatherwax@ll.mit.edu
% Voice: (781) 981-5370       Fax: (781) 981-0721
% 
% Please send comments and especially bug reports to the
% above email address.
% 
%-----

ni = [ -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 ];
xi = (pi/4)*ni;

g = zeros( size( ni ) );                % Initialize g;
for i=1:10
  g = g + (12*((-1)^(i+1))/(i^3))*sin(i*xi);
end

figure; hold on;
plot( xi, g, '-or' );
plot( xi, pi^2*xi - xi.^3, '-og' );