function humps_lagrange ( n )

  x_data = linspace ( 0.0, 2.0, n );
  y_data = humps ( x_data );

  x = linspace ( 0.0, 2.0, 51 );
  y = humps ( x );
  y2 = zeros ( size ( x ) );
  for i = 1 : n
    y2 = y2 + y_data(i) * ell(i,x_data,x);
  end

  plot ( x, y, 'b-', ...
         x, y2, 'r-', ...
         x_data, y_data, 'k.', 'markersize', 25 );

  print ( '-dpng', 'humps_lagrange.png' );

  return
end

