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function [ y, z ] = FIRfilter( coef, z, x, norder ) 
 
global szsubf olpc; 
 
if nargin==4 
    order=norder; 
else 
    order=olpc; 
end 
     
b=coef(2:order+1);                           % Cut off 1 in the coefficients 
 
for t=1:szsubf 
    y(t) = sum(z(1:order).*b(order:-1:1))+x(t); 
    z(1:order)=[z(2:order),x(t)]; 
end