d3tanh.m

来自「非线型因素分析matlab仿真程序包」· M 代码 · 共 25 行

function [d1, d2, d3] = d3tanh(a, y)
% DTANH  Calculate three first derivatives of 'tanh'

% Copyright (C) 1999-2004 Antti Honkela, Harri Valpola,
% and Xavier Giannakopoulos.
%
% This package comes with ABSOLUTELY NO WARRANTY; for details
% see License.txt in the program package.  This is free software,
% and you are welcome to redistribute it under certain conditions;
% see License.txt for details.

if nargin < 2,
  y = tanh(a);
end

if nargout == 1
  d1 = 1 - (y .^ 2);
else
  y2 = y .^ 2;

  d1 = 1 - y2;
  d2 = -2 * y .* d1;
  d3 = 2 * d1 .* (3*y2 - 1);
end