function[x]=chelosky_dejen_2018(M,b)
if det(M)==0
    error('algorithm is not working')
end
n = length( M );
L = zeros( n, n );
for i=1:n
    L(i, i) = sqrt( M(i, i) - L(i, :)*L(i, :)' );

    for j=(i + 1):n
        L(j, i) = ( M(j, i) - L(i, :)*L(j, :)' )/L(i, i);
    end
    
end
Y=L\b;
    x=L'\Y;
end