Entropy of an audio signal

i am trying to find the entropy of an audio signal, so i need first the probability of appearance of each values of the signal, the problem is, i have this values due to the histogram i did but how can i get those values and save them into a vector in order to fins the entropy? i already have the entropy function!

function entro = entropia(x)
%UNTITLED Summary of this function goes here
%   Detailed explanation goes here
x=[.5 .25 .125 .0625 .0625]; % these values must be the appearence probability of my signal values

tam=length(x); % tamaño del vector x

suma= 0;

for i=1:tam % hacer un for desde 1 hasta el tamaño del vector x 

h= x(i)*log2(1/x(i));  % funcion de entropia
suma = suma+ h; % la suma acumula los valores obtenidos por cada valor del vector x

end

entro = suma;
coder.extrinsic('disp')
disp (entro);

end

please help!

Answer 1

[maria]

Maybe it's too later, but:

1. For extract probability use 'hist' function: p = hist(signal) or p = hist(signal, lengths)

2. Don't need that long code for entropy! I think it's wrong, because is 'log2(x(i))' and not 'log2(1/x(i))'. But really better you replace ALL and use only: -sum(p.*log2(p))

Good Luck!