function quartic_gauss ( n, a, b )

%% quartic_gauss uses Gauss quadrature to estimate integral quartic(x) dx
%
  q_exact = quartic_int ( a, b );

  [ x, w ] = gauss_ab ( n, a, b );
  q_gauss = w' * quartic(x);

  e = q_exact - q_gauss;

  fprintf ( 1, '\n' );
  fprintf ( 1, 'quartic_gauss:\n' );
  fprintf ( 1, '  Gauss quadrature of quartic(x)\n' );
  fprintf ( 1, '  Interval = [%g,%g]\n', a, b );
  fprintf ( 1, '  N = %d\n', n );
  fprintf ( 1, '  I(quartic(),a,b) = %g\n', q_exact );
  fprintf ( 1, '  G(quartic(),a,b) = %g\n', q_gauss );
  fprintf ( 1, '  E = I-G          = %g\n', e );

  return
end

