function [ w, x, y ] = triangle_quadrature_six ( )

%*****************************************************************************80
%
%% TRIANGLE_QUADRATURE_SIX returns a six-point quadrature rule for the triangle.
%
%  Discussion:
%
%    The rule is for the unit triangle.
%
%    The integral of F(X,Y) is approximated by
%
%      I( F(X,Y) ) = 1/2 sum W(I) * F(X(I),Y(I) ).
%
%    This is rule number 5 from Strang and Fix.
%
%  Licensing:
%
%    This code is distributed under the GNU LGPL license. 
%
%  Modified:
%
%    19 March 2011
%
%  Author:
%
%    John Burkardt
%
%  Reference:
%
%    Gilbert Strang, George Fix,
%    An Analysis of the Finite Element Method,
%    Prentice Hall, 1973, page 184,
%    ISBN: 096140888X,
%    LC: TA335.S77.
%
%  Parameters:
%
%    Output, real W(6), the weights.
%
%    Output, real X(6), Y(6), the points.
%
  a = 0.816847572980459;
  b = 0.091576213509771;
  c = 0.108103018168070;
  d = 0.445948490915965;
  r = 0.109951743655322;
  s = 0.223381589678011;

  x = [ a, b, b, c, d, d ];
  y = [ b, a, b, d, c, d ];
  w = [ r, r, r, s, s, s ];

  return
end
