entrupd

Purpose

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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