I NEED HELP: Differences between MATLAB and Octave

[Marco Boni]

The simple code I've attached to this mail runs very fast under Matlab,
while it is executed very slow under Octave.

Why? Where I've failed!
 
 

-- 
Marco Boni
Viale delle Magnolie, 4
50142 - Firenze
Cell.: +39 335 6079353
Home : +39 055 7398033
Email: address@hidden
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 My machine is an i686 and running Red Hat Linux 7.2
               Why don't you try it?
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%entropia di un segnale random

closeplot;
clear all;
k=16;
nt=2^k;
a=floor(rand(1,nt)+.5);
dt=k+4;
for n=1:dt
   dimb=n;
   numb=floor(nt/dimb);
   dim=dimb*numb;
   aa=reshape(a(1:dim),dimb,numb);
   x=(1:1:n)-1;
   xx=2.^x;
   ris1=xx*aa+1;
   ris2=hist(ris1,2^n);
   ris3=ris2(find(ris2));
   %
size(ris3,2)/size(ris2,2);
   n
   p=ris3/numb;
   ris(n)=-sum(p.*log(p));
end;
entr=diff(ris);
entr(1)=log(2);
plot(entr);hold;plot(entr,'*');
plot(log(2)*ones(1,dt),'r');grid
input ("Pick a number, any number! ")