function sigmoid_derivative_value_test ( )

%*****************************************************************************80
%
%% sigmoid_derivative_value_test() tests sigmoid_derivative_value().
%
%  Licensing:
%
%    This code is distributed under the MIT license.
%
%  Modified:
%
%    22 May 2024
%
%  Author:
%
%    John Burkardt
%
  fprintf ( 1, '\n' );
  fprintf ( 1, 'sigmoid_derivative_value_test():\n'  );
  fprintf ( 1, '  sigmoid_derivative_value() evaluates the nth derivative\n' );
  fprintf ( 1, '  of the sigmoid function at the location x.\n' );

  for n = 0 : 3

    xvec = linspace ( -5.0, +5.0, 51 );
    yvec = zeros ( 1, 51 );
    for i = 1 : 51
      yvec(i) = sigmoid_derivative_value ( n, xvec(i) );
    end

    clf ( );
    plot ( xvec, yvec, 'linewidth', 2 );
    grid ( 'on' );
    xlabel ( '<-- x -->' );
    ylabel ( '<-- s(x) -->' );
    s = sprintf ( '%d derivative of sigmoid function', n );
    title ( s );
    filename = sprintf ( 'sigmoid_derivative_%d.png', n );
    print ( '-dpng', filename );
    printf ( '  Graphics saved as "%s"\n', filename );

  end

  return
end

