next up previous contents index
Next: fct1d Up: Reference Previous: fvalues   Contents   Index


$ \bigcirc$Name

entropy Compute the entropy given by an histogram

$ \bigcirc$Command Synopsis

entropy Histo .

Histo : Input histogram (fsignal)

. (screen output) :

$ \bigcirc$Function Summary

void entropy (Histo , Entropy )

Fsignal Histo ;

double *Entropy ;

$ \bigcirc$Description

This module computes the Shannon entropy of the input histogram. If {sk}1 $\scriptstyle \leq$ k $\scriptstyle \leq$ K are the values of the input fsignal, then entropy computes

- $\displaystyle \sum_{{k=1}}^{K}$$\displaystyle \tilde{{s}}_{k}^{}$log$\displaystyle \tilde{{s}}_{k}^{}$

where $ \tilde{{s}}_{k}^{}$ = sk/($ \sum_{{l=1}}^{K}$sl). It is assumed that the sk's are positive.

$ \bigcirc$See Also

fscalq, fvq.

$ \bigcirc$Version 1.0

Last Modification date : Thu Nov 29 20:23:56 2001

$ \bigcirc$Author

Jean-Pierre D'Ales

mw 2004-05-05