I want to create a STATE SPACE function. I have converted higher order differential into first order differential. but I am not able to form matrix A(state matrix) and matrix B(input/control matrix) from the equations. Please help

function zp = statespace(t,z);

zp(1) = z(2);

zp(2) = w/m - c*z(2)/m - k*[z(1)*cos(phi(i)) + z(3)*sin(phi(i))].^(3/2);

zp(3) = z(4);

zp(4) = - c*z(4)/m - k*[z(1)*cos(phi(i)) + z(3)*sin(phi(i)) ].^(3/2);