entrupd (Wavelet Toolbox)

Entropy update (wavelet packet)

Syntax

T = entrupd(T,ENT)
T = entrupd(T,ENT,PAR)

Description

entrupd is a one- or two-dimensional wavelet packet utility.

T = entrupd(T,ENT) or T = entrupd(T,ENT,PAR) returns for a given wavelet packet tree T, the updated tree using the entropy function ENT with the optional parameter PAR (see wenergy for more information).

Examples

% The current extension mode is zero-padding (see dwtmode).

% Load signal. 
load noisdopp; x = noisdopp;

% Decompose x at depth 2 with db1 wavelet packets 
% using shannon entropy. 
t = wpdec(x,2,'db1','shannon');

% Read entropy of all the nodes. 
nodes = allnodes(t);
ent = read(t,'ent',nodes);
ent'
ent =
    1.0e+04 *
    -5.8615 -6.8204 -0.0350 -7.7901 -0.0497 -0.0205 -0.0138

% Update nodes entropy. 
t = entrupd(t,'threshold',0.5); 
nent = read(t,'ent');
nent'
nent =
    937 488 320 241 175 170 163

See Also
wenergy, wpdec, wpdec2

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