function value = p29_r8 ( action, name, value )

%*****************************************************************************80
%
%% P29_R8 sets or gets R8 parameters for problem 29.
%
%  Licensing:
%
%    This code is distributed under the MIT license.
%
%  Modified:
%
%    19 March 2007
%
%  Author:
%
%    John Burkardt
%
%  Input:
%
%    string ACTION,
%    'D' sets the parameter to its default value;
%    'G' gets a parameter.
%    'R' sets the parameter to a random value.
%    'S' sets a parameter,
%
%    string NAME, the name of the variable.
%    'R' is the radius.
%
%    real VALUE.
%    * If ACTION = 'S', then VALUE is an input quantity, and is the
%      new value to be assigned to NAME.
%
%  Output:
%
%    real VALUE.
%    * If ACTION = 'G' or 'R', then VALUE is an output quantity, 
%      and is the current value of NAME.
%
  persistent r;

  if ( action == 'D' || action == 'd' )

    if ( name == 'R' || name == 'r' || name == '*' )
      r = 0.3;
    end

  elseif ( action == 'G' || action == 'g' )

    if ( name == 'R' || name == 'r' )
      value = r;
    else
      fprintf ( 1, '\n' );
      fprintf ( 1, 'P29_R8 - Fatal error!\n' );
      fprintf ( 1, '  Unrecognized name = "%s".\n', name );
      error ( 'P29_R8 - Fatal error!' );
    end

  elseif ( action == 'R' || action == 'r' )

    if ( name == 'R' || name == 'r' )
      r = rand ( 1, 1 );
      value = r;
    else
      fprintf ( 1, '\n' );
      fprintf ( 1, 'P29_R8 - Fatal error!\n' );
      fprintf ( 1, '  Unrecognized name = "%s".\n', name );
      error ( 'P29_R8 - Fatal error!' );
    end

  elseif ( action == 'S' || action == 's' )

    if ( name == 'R' || name == 'r' )
      r = value;
    else
      fprintf ( 1, '\n' );
      fprintf ( 1, 'P29_R8 - Fatal error!\n' );
      fprintf ( 1, '  Unrecognized name = "%s".\n', name );
      error ( 'P29_R8 - Fatal error!' );
    end

  else

    fprintf ( 1, '\n' );
    fprintf ( 1, 'P29_R8 - Fatal error!\n' );
    fprintf ( 1, '  Unrecognized action = "%s".\n', action );
    error ( 'P29_R8 - Fatal error!' );

  end

  return
end
