function [ w, xyz ] = tetrahedron_unit_o15 ( )

%*****************************************************************************80
%
%% tetrahedron_unit_o15() returns a 15 point quadrature rule for the unit tetrahedron.
%
%  Discussion:
%
%    The integration region is:
%
%      0 <= X
%      0 <= Y
%      0 <= Z
%      X + Y + Z <= 1.
%
%  Licensing:
%
%    This code is distributed under the MIT license.
%
%  Modified:
%
%    19 April 2009
%
%  Author:
%
%    John Burkardt
%
%  Reference:
%
%    Carlos Felippa,
%    A compendium of FEM integration formulas for symbolic work,
%    Engineering Computation,
%    Volume 21, Number 8, 2004, pages 867-890.
%
%  Output:
%
%    real W(15), the weights.
%
%    real XYZ(3,15), the abscissas.
%
  w(1:15,1) = [ ...
    0.071937083779018620010, ...
    0.071937083779018620010, ...
    0.071937083779018620010, ...
    0.071937083779018620010, ...
    0.069068207226272385281, ...
    0.069068207226272385281, ...
    0.069068207226272385281, ...
    0.069068207226272385281, ...
    0.052910052910052910053, ...
    0.052910052910052910053, ...
    0.052910052910052910053, ...
    0.052910052910052910053, ...
    0.052910052910052910053, ...
    0.052910052910052910053, ...
    0.11851851851851851852 ];

  xyz(1:3,1:15) = [ ...
    0.72408676584183090163,  0.091971078052723032789,  0.091971078052723032789; ...
    0.091971078052723032789,  0.72408676584183090163,  0.091971078052723032789; ...
    0.091971078052723032789,  0.091971078052723032789,  0.72408676584183090163; ...
    0.091971078052723032789,  0.091971078052723032789,  0.091971078052723032789; ...
    0.040619116511110274837,  0.31979362782962990839,  0.31979362782962990839; ...
    0.31979362782962990839,  0.040619116511110274837,  0.31979362782962990839; ...
    0.31979362782962990839,  0.31979362782962990839,  0.040619116511110274837; ...
    0.31979362782962990839,  0.31979362782962990839,  0.31979362782962990839; ...
    0.44364916731037084426,  0.44364916731037084426,  0.056350832689629155741; ...
    0.44364916731037084426,  0.056350832689629155741,  0.44364916731037084426; ...
    0.44364916731037084426,  0.056350832689629155741,  0.056350832689629155741; ...
    0.056350832689629155741,  0.44364916731037084426,  0.44364916731037084426; ...
    0.056350832689629155741,  0.44364916731037084426,  0.056350832689629155741; ...
    0.056350832689629155741,  0.056350832689629155741,  0.44364916731037084426; ...
    0.25000000000000000000,  0.25000000000000000000,  0.25000000000000000000 ]';

  return
end
