function r8lib_test139 ()

%*****************************************************************************80
%
%% TEST139 tests R8VEC_SORT_HEAP_D.
%
%  Licensing:
%
%    This code is distributed under the GNU LGPL license.
%
%  Modified:
%
%    14 April 2009
%
%  Author:
%
%    John Burkardt
%
  n = 20;

  fprintf ( 1, '\n' );
  fprintf ( 1, 'TEST139\n' );
  fprintf ( 1, '  R8VEC_SORT_HEAP_D descending sorts a DVEC.\n' );
 
  b = 0.0;
  c = 3.0 * n;
  seed = 123456789;

  [ a, seed ] = r8vec_uniform_ab ( n, b, c, seed );
 
  r8vec_print_some ( n, a, 1, 10, '  Original array:' );

  a = r8vec_sort_heap_d ( n, a );

  r8vec_print_some ( n, a, 1, 10, '  Descending sorted array:' );

  return
end