function r8lib_test1255 ( )

%*****************************************************************************80
%
%% TEST1255 tests R8VEC_INDEXED_HEAP_D_EXTRACT and related routines.
%
%  Licensing:
%
%    This code is distributed under the GNU LGPL license.
%
%  Modified:
%
%    17 August 2010
%
%  Author:
%
%    John Burkardt
%
  m = 20;
  n_max = 20;

  fprintf ( 1, '\n' );
  fprintf ( 1, 'TEST1255\n' );
  fprintf ( 1, '  For an indexed R8VEC,\n' );
  fprintf ( 1, '  R8VEC_INDEXED_HEAP_D_INSERT inserts a value into the heap.\n' );
  fprintf ( 1, '  R8VEC_INDEXED_HEAP_D_EXTRACT extracts the maximum value;\n' );
  fprintf ( 1, '  R8VEC_INDEXED_HEAP_D_MAX reports the maximum value.\n' );
  fprintf ( 1, '\n' );
  fprintf ( 1, '  These 3 operations are enough to model a priority queue.\n' );
%
%  Set the data array.  To keep things easy, we will use the indicator vector.
%
  a = r8vec_indicator ( m );
%
%  The index array will initially be a random subset of the numbers 1 to M,
%  in random order.
%
  n = 5;
  indx(1:11,1) = [ 9, 2, 8, 14, 5, 7, 15, 1, 19, 20, 3 ]';

  r8vec_print ( m, a, '  The data vector:' );
  i4vec_print ( n, indx, '  The index vector:' );
  fprintf ( 1, '\n' );
  fprintf ( 1, '  A(INDX):\n' );
  fprintf ( 1, '\n' );
  for i = 1 : n
    fprintf ( 1, '  %4d  %14.6f\n', i, a(indx(i)) );
  end
%
%  Create the descending heap.
%
  indx = r8vec_indexed_heap_d ( n, a, indx );

  i4vec_print ( n, indx, '  The index vector after heaping:' );
  fprintf ( 1, '\n' );
  fprintf ( 1, '  A(INDX) after heaping:\n' );
  fprintf ( 1, '\n' );
  for i = 1 : n
    fprintf ( 1, '  %4d  %14.6f\n', i, a(indx(i)) );
  end
%
%  Insert five entries, and monitor the maximum.
%
  for i = 1 : 5

    indx_insert = indx(n+1);

    fprintf ( 1, '\n' );
    fprintf ( 1, '  Inserting value %f\n', a(indx_insert) );

    [ n, indx ] = r8vec_indexed_heap_d_insert ( n, a, indx, indx_insert );

    indx_max = r8vec_indexed_heap_d_max ( n, a, indx );

    fprintf ( 1, '  Current maximum is %f\n', a(indx_max) );

  end
  r8vec_print ( m, a, '  The data vector after insertions:' );
  i4vec_print ( n, indx, '  The index vector after insertions:' );
  fprintf ( 1, '\n' );
  fprintf ( 1, '  A(INDX) after insertions:\n' );
  fprintf ( 1, '\n' );
  for i = 1 : n
    fprintf ( 1, '  %4d  %14.6f\n', i, a(indx(i)) );
  end
%
%  Extract the first 5 largest elements.
%
  fprintf ( 1, '\n' );
  fprintf ( 1, '  Now extract the maximum several times.\n' );
  fprintf ( 1, '\n' );

  for i = 1 : 5
    [ indx_extract, n, indx ] = r8vec_indexed_heap_d_extract ( n, a, indx );
    fprintf ( 1, '  Extracting maximum element A(%d) = %f\n', ...
      indx_extract, a(indx_extract) );
  end

  r8vec_print ( m, a, '  The data vector after extractions:' );
  i4vec_print ( n, indx, '  The index vector after extractions:' );
  fprintf ( 1, '\n' );
  fprintf ( 1, '  A(INDX) after extractions:\n' );
  fprintf ( 1, '\n' );
  for i = 1 : n
    fprintf ( 1, '  %4d  %14.6f\n', i, a(indx(i)) );
  end

  return
end