data = load ( 'cubature_prism_sym_p20_n518_expand.txt' );
output = fopen ( 'rule20.c', 'w' );
n = size ( data, 1 );

fprintf ( output, 'void rule20 ( int n, double x[], double y[], double z[], double w[] )\n' ); 
fprintf ( output, '\n' );
fprintf ( output, '/******************************************************************************/\n' );
fprintf ( output, '/*\n' );
fprintf ( output, '  Purpose:\n' );
fprintf ( output, '\n' );
fprintf ( output, '    rule20() returns the prism rule of precision 20.\n' );
fprintf ( output, '\n' );
fprintf ( output, '  Discussion:\n' );
fprintf ( output, '\n' );
fprintf ( output, '    We suppose we are given a triangular prism P with vertices\n' );
fprintf ( output, '    (1,0,0), (0,1,0), (0,0,0),\n' );
fprintf ( output, '    (1,0,1), (0,1,1), (0,0,1),\n' );
fprintf ( output, '    We call a rule with n points, returning coordinates\n' );
fprintf ( output, '    x, y, z, and weights w.  Then the integral I of f(x,y,z) over P is \n' );
fprintf ( output, '    approximated by Q as follows:\n' );
fprintf ( output, '\n' );
fprintf ( output, '    Q = volume(P) * sum ( 1 <= i <= n ) w(i) * f(x(i),y(i),z(i)) \n' );
fprintf ( output, '\n' );
fprintf ( output, '  Licensing:\n' );
fprintf ( output, '\n' );
fprintf ( output, '    This code is distributed under the GNU LGPL license.\n' );
fprintf ( output, '\n' );
fprintf ( output, '  Modified:\n' );
fprintf ( output, '\n' );
fprintf ( output, '    03 May 2023\n' );
fprintf ( output, '\n' );
fprintf ( output, '  Author:\n' );
fprintf ( output, '\n' );
fprintf ( output, '    John Burkardt\n' );
fprintf ( output, '\n' );
fprintf ( output, '  Reference:\n' );
fprintf ( output, '\n' );
fprintf ( output, '    Jan Jaskowiec, Natarajan Sukumar,\n' );
fprintf ( output, '    High order symmetric cubature rules for tetrahedra and pyramids,\n' );
fprintf ( output, '    International Journal of Numerical Methods in Engineering,\n' );
fprintf ( output, '    Volume 122, Number 1, pages 148-171, 24 August 2020.\n' );
fprintf ( output, '\n' );
fprintf ( output, '  Input:\n' );
fprintf ( output, '\n' );
fprintf ( output, '    int n: the number of quadrature points for this rule.\n' );
fprintf ( output, '\n' );
fprintf ( output, '  Output:\n' );
fprintf ( output, '\n' );
fprintf ( output, '    double x(n), y(n), z(n): the coordinates of quadrature points.\n' );
fprintf ( output, '\n' );
fprintf ( output, '    double w[n]: the quadrature weights, which sum to 1.\n' );
fprintf ( output, '*/\n' );
fprintf ( output, '{\n' );
x = data(:,1);
y = data(:,2);
z = 0.5 * ( data(:,3) + 1.0 );
w = data(:,4);
fprintf ( output, '  static double x_save[] = {\n' );
for i = 1 : n - 1
  fprintf ( output, '    %24.16f,\n', x(i) );
end
fprintf ( output, '    %24.16f };\n', x(n) );

fprintf ( output, '\n' );
fprintf ( output, '  static double y_save[] = {\n' );
for i = 1 : n - 1
  fprintf ( output, '    %24.16f,\n', y(i) );
end
fprintf ( output, '    %24.16f };\n', y(n) );

fprintf ( output, '\n' );
fprintf ( output, '  static double z_save[] = {\n' );
for i = 1 : n - 1
  fprintf ( output, '    %24.16f,\n', z(i) );
end
fprintf ( output, '    %24.16f };\n', z(n) );

fprintf ( output, '\n' );
fprintf ( output, '  double w_save[] = {\n' );
for i = 1 : n - 1
  fprintf ( output, '    %24.16f,\n', w(i) );
end
fprintf ( output, '    %24.16f };\n', w(n) );
fprintf ( output, '\n' );

fprintf ( output, '  r8vec_copy ( n, x_save, x );\n' );
fprintf ( output, '  r8vec_copy ( n, y_save, y );\n' );
fprintf ( output, '  r8vec_copy ( n, z_save, z );\n' );
fprintf ( output, '  r8vec_copy ( n, w_save, w );\n' );

fprintf ( output, '\n' );
fprintf ( output, '  return;\n' );
fprintf ( output, '}\n' );

fclose ( output );
