#include <costshannon.h>
Inheritance diagram for costshannon::
Public Methods  
costshannon (packnode< double > *node)  
Calculate a modified version of the the Shannon entropy cost function for the wavelet packet tree, filling in the cost value at each node. More...  
Protected Methods  
double  costCalc (packnode< double > *node) 
An implementation of a modified version of the Shannon entropy function as a wavelet packet cost function. More... 
Definition at line 50 of file costshannon.h.

Calculate a modified version of the the Shannon entropy cost function for the wavelet packet tree, filling in the cost value at each node.
Definition at line 60 of file costshannon.h. 00060 { traverse( node ); } 

An implementation of a modified version of the Shannon entropy function as a wavelet packet cost function. This is described in section 8.3.2 of Ripples in Mathematics by Jensen and la CourHarbo. The log function here is the natural log (sometimes denoted as ln()). Note that the result of the entropy function is always negative. Reimplemented from costbase. Definition at line 21 of file costshannon.cpp. 00022 { 00023 assert( node != 0 ); 00024 00025 size_t len = node>length(); 00026 const double *a = node>getData(); 00027 00028 double sum = 0.0; 00029 for (int i = 0; i < len; i++) { 00030 double val = 0.0; 00031 if (a[i] != 0.0) { 00032 double square = a[i] * a[i]; 00033 val = square * log( square ); 00034 } 00035 sum = sum + val; 00036 } 00037 00038 return sum; 00039 } // costshannon 