function d = diagGauss(a,b,c,d)
    n = size(d)(1);
    for i=1:n-1
        if (i==1)
            c(1) /= b(1);
            d(1) /= b(1);
        else
            c(i) = c(i) / (b(i)-c(i-1)*a(i-1));
        d(i) = (d(i) - d(i-1)*a(i-1)) / (b(i)-c(i-1)*a(i-1));
        end
    end
    d(n) = (d(n) - d(n-1)*a(n-1)) / (b(n)-c(n-1)*a(n-1));
    for i=size(d)(1)-1:-1:1
        d(i) = d(i) - c(i)*d(i+1);
    end
end