## [46726a]: inst / jointentropy.m  Maximize  Restore  History

### 44 lines (40 with data), 1.5 kB

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43``` ```## Copyright (C) 2006 Muthiah Annamalai ## ## This program is free software; you can redistribute it and/or modify ## it under the terms of the GNU General Public License as published by ## the Free Software Foundation; either version 2 of the License, or ## (at your option) any later version. ## ## This program is distributed in the hope that it will be useful, ## but WITHOUT ANY WARRANTY; without even the implied warranty of ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the ## GNU General Public License for more details. ## ## You should have received a copy of the GNU General Public License ## along with this program; If not, see . ## -*- texinfo -*- ## @deftypefn {Function File} {} jointentropy (@var{xy}) ## ## Computes the joint entropy of the given channel transition matrix. ## By definition we have @code{H(@var{x}, @var{y})} given as ## @code{H(@var{x}:@var{y}) = SUMx(SUMy(P(@var{x}, @var{y}) * ## log2(p(@var{x}, @var{y}))))} ## @end deftypefn ## @seealso{entropy, conditionalentropy} function val=jointentropy(XY) if nargin < 1 || ~ismatrix(XY) error('Usage: jointentropy(XY) where XY is the transition matrix'); end val=0.0; S=size(XY); if (S(1)==1) val=entropy(XY) else row=S(2); for i=1:row val=val+entropy(XY(i,:)); end end return end %!assert(jointentropy([0.7 0.3; 0.3 0.7]),1.7626,1e-4) ```