clear all;close all; 
fvz=44100; f=440; N=10; 
myz0=exp(i*2*pi*f/fvz);
my_hn=[1 -2*real(myz0) 1];
x=0:1:N*fvz-1;
t=x/fvz; 
noise=rand(1,N*fvz);
val=cos(2*pi*t*f)+noise; 
cval=conv(val,my_hn); 
plot(cval(3:100)); 
sum(cval.*cval)/(N*fvz);
soundsc(val, 44100); display("hram sum+f signal, stlac klavesu"); pause;
soundsc(cval, 44100);display("hram filtrovany sum+f signal");