inf. sec. 04

gistfile1.txt

function [ out ] = berlekamp_massey(  )
    
    z=[ 0   0   0  0  1  1 1  1  1  0  1  0  1  0  0  1  1  0  0  0  1  0 0 0 0  1 1 1  1  1];
    
    n = length(z);
    c = zeros(1,n);
    b= zeros(1,n);
    c(1) = 1;
    b(1) = 1;
    
    
    for r=1:n
        d = 0;
        for j = 0:r - 1
            d= xor(d,  z(r-j)*c(j+1));
        end
        
        if (d ~= 0)
            t = xor(c , [0 b(1:length(b)-1)]);
            b = c;
            c = t;
        else 
            % b(x) = xb(x)
            b = [0 b(1:length(b)-1)];%circshift(b, [0 1]);
        end
    end
    
    log_polynom(c);
    out = find(c, 1, 'last' ) - 1;

end


function []= log_polynom( poly )
%UNTITLED3 Summary of this function goes here
%   Detailed explanation goes here
    str = '';
    first = true;
    for i=1:length(poly)
        if (poly(i) == 1)
            if (first)
               first = false;
            else 
               str = [str ' + ']; 
            end
                
            if (i)==1
                str = [str  '1'];
            else 
                
                str = [str , 'x'];
                if (i-1 ~= 1)
                    str = [str,'^', char(int2str(i-1))]; 
                end
                
            end
        end
    end

    str
end