function [K] = MacierzSztywnosci3(E, A, Iz, l, s, c)

Ke = E*Iz/(l^3)*[A*l^2/Iz 0 0 -A*l^2/Iz 0 0;
                0 12 6*l 0 -12 6*l;
                0 6*l 4*l^2 0 -6*l 2*l^2;
                -A*l^2/Iz 0 0 A*l^2/Iz 0 0;
                0 -12 -6*l 0 12 -6*l;
                0 6*l 2*l^2 0 -6*l 4*l^2];

R = zeros(6,6);

R(1,1) = c;
R(1,2) = s;
R(2,1) = -s;
R(2,2) = c;
R(3,3) = 1;
R(4,4) = c;
R(4,5) = s;
R(5,4) = -s;
R(5,5) = c;
R(6,6) = 1;

K = R'*Ke*R;

end