function ent = wentropy(x,t_ent,in3)

%WENTROPY Entropy (wavelet packet).

%   E = WENTROPY(X,T,P) returns the entropy E of the

%   vector or matrix X.

%   In both cases, output E is a real number.

%

%   T is a string containing the type of entropy:

%     T = 'shannon', 'threshold', 'norm',

%         'log energy' (or 'logenergy'), 'sure', 'user'.

%   or

%     T = FunName (which is any other string except those

%         previous Entropy Type Name listed above).

%         FunName is the MATLAB file name of your own

%         entropy function.

%

%   P is an optional parameter depending on the value of T:

%     If T = 'shannon' or 'log energy', P is not used.

%     If T = 'threshold' or 'sure', P is the threshold

%     and must be a positive number.

%     If T = 'norm', P is the power and must be such that 1 <= P.

%     If T = 'user', P is a string containing the MATLAB file name

%     of your own entropy function, with a single input X.

%     If T = FunName, P is an optional parameter with no constraints.

%

%   E = WENTROPY(X,T) is equivalent to E = WENTROPY(X,T,0).

%   M. Misiti, Y. Misiti, G. Oppenheim, J.M. Poggi 12-Mar-96.

%   Last Revision 16-Aug-2012.

%   Copyright 1995-2012 The MathWorks, Inc.

%   $Revision: 1.13.4.9 $

% Check arguments.

narginchk(2,3);

x = double(x(:));

switch t_ent

case 'shannon'       % in3 not used.

x = x(x~=0).^2;

ent = -sum(x.*log(eps+x));

case 'threshold'     % in3 is the threshold.

if nargin==2 || isempty(in3) || ischar(in3) || in3<0 , errStop; end

x = abs(x);

ent = sum(x > in3);

case 'sure'          % in3 is the threshold.

if nargin==2 || isempty(in3) || ischar(in3) || in3<0 , errStop; end

n = length(x);

x2 = x.^2; t2 = in3.^2;

xgt =  sum(x2 > t2); xlt = n - xgt;

ent = n - (2*xlt) + (t2*xgt) + sum(x2.*(x2 <= t2));

case 'norm'          % in3 = p , ent = (lp_norm)^p.

if nargin==2 || isempty(in3) || ischar(in3) || in3<1 , errStop; end

x = abs(x);

ent = sum(x.^in3);

case {'energy','log energy','logenergy'}     % in3 not used.

x = x(x~=0).^2;

ent = sum(log(x));

case 'user'  % in3 = '' , user entropy.

if nargin==2 || isempty(in3) || ~ischar(in3) , errStop; end

ent = feval(in3,x);

otherwise

%-----------------------------------------------------------%

% Bug & Generalization: temporary Patch (M.M. 20 June 2001) %

% For user defined entropy.                                 %

%-----------------------------------------------------------%

try

k = find(t_ent=='&');

entFunct = t_ent(k+1:end);

ent = feval(entFunct,x);

catch %#ok

try

if nargin==2 ,

ent = feval(t_ent,x);

else

ent = feval(t_ent,x,in3);

end

catch

errStop;

end

end

end

prec = 1.0E-10;

if abs(ent)

% Internal Function

function errStop

errargt(mfilename,...

getWavMSG('Wavelet:FunctionArgVal:Invalid_ArgVal'),'msg');

error(message('Wavelet:FunctionArgVal:Invalid_ArgVal'));