function [ x, y, z, w ] = rule03 ( )

%*****************************************************************************80
%
%% rule03() returns the hexahedron rule of precision 3.
%
%  Discussion:
%
%    We suppose we are given a hexahedron H with vertices
%    (0,0,0), (1,0,0), (1,1,0), (0,1,0), (0,0,1), (1,0,1), (1,1,1), (0,1,1),
%    We call a rule with n points, returning coordinates
%    x, y, z, and weights w.  Then the integral I of f(x,y,z) over H is 
%    approximated by Q as follows:
%
%    Q = volume(H) * sum ( 1 <= i <= n ) w(i) * f(x(i),y(i),z(i)) 
%
%  Licensing:
%
%    This code is distributed under the MIT license.
%
%  Modified:
%
%    01 May 2023
%
%  Author:
%
%    John Burkardt
%
%  Reference:
%
%    Freddie Witherden, Peter Vincent,
%    On the identification of symmetric quadrature rules for finite element methods,
%    Computers and Mathematics with Applications,
%    Volume 69, pages 1232-1241, 2015.
%
%  Output:
%
%    real x(n), y(n), z(n): the coordinates of quadrature points.
%
%    real w(n): the quadrature weights, which sum to 1.
%
  x = [ ...
          0.0000000000000000, ...
          0.5000000000000000, ...
          0.5000000000000000, ...
          0.5000000000000000, ...
          1.0000000000000000, ...
          0.5000000000000000 ];

  y = [ ...
          0.5000000000000000, ...
          0.5000000000000000, ...
          1.0000000000000000, ...
          0.5000000000000000, ...
          0.5000000000000000, ...
          0.0000000000000000 ];

  z = [ ...
          0.5000000000000000, ...
          1.0000000000000000, ...
          0.5000000000000000, ...
          0.0000000000000000, ...
          0.5000000000000000, ...
          0.5000000000000000 ];

  w = [ ...
          0.1666666666666667, ...
          0.1666666666666667, ...
          0.1666666666666667, ...
          0.1666666666666667, ...
          0.1666666666666667, ...
          0.1666666666666667 ];

  return
end
