function quad_angles_test ( )

%*****************************************************************************80
%
%% QUAD_ANGLES_TEST tests QUAD_ANGLES.
%
%  Licensing:
%
%    This code is distributed under the GNU LGPL license.
%
%  Modified:
%
%    01 August 2018
%
%  Author:
%
%    John Burkardt
%
  fprintf ( 1, '\n' );
  fprintf ( 1, 'QUAD_ANGLES_TEST\n' );
  fprintf ( 1, '  QUAD_ANGLES returns the angles of a quadrilateral\n' );
  fprintf ( 1, '  in radians.\n' );

  q = [ ...
    0.0, 1.0, 1.0, 0.0; ...
    0.0, 0.0, 1.0, 1.0 ];

  r82vec_print ( 4, q, '  Quadrilateral coordinates:' );
  angles = quad_angles ( q );
  r8vec_print ( 4, angles, '  Interior angles:' );
  fprintf ( 1, '  Angles sum to %g\n',sum ( angles ) );

  q = [ ...
    0.0, 1.0, 2.0, 0.0; ...
    0.0, 0.0, 1.0, 1.0 ];

  r82vec_print ( 4, q, '  Quadrilateral coordinates:' );
  angles = quad_angles ( q );
  r8vec_print ( 4, angles, '  Interior angles:' );
  fprintf ( 1, '  Angles sum to %g\n',sum ( angles ) );

  q = [ ...
    0.0, 1.0, 0.25, 0.0; ...
    0.0, 0.0, 0.25, 1.0 ];

  r82vec_print ( 4, q, '  Quadrilateral coordinates:' );
  angles = quad_angles ( q );
  r8vec_print ( 4, angles, '  Interior angles:' );
  fprintf ( 1, '  Angles sum to %g\n',sum ( angles ) );

  q = [ ...
    0.0, 1.0, -0.5, 0.0; ...
    0.0, 0.0,  0.5, 1.0 ];

  r82vec_print ( 4, q, '  Quadrilateral coordinates:' );
  angles = quad_angles ( q );
  r8vec_print ( 4, angles, '  Interior angles:' );
  fprintf ( 1, '  Angles sum to %g\n',sum ( angles ) );

  return
end
