so3_cayinv.m

function f = so3_cayinv(v)
  
p = (4+v'*v);

f = 1/p*[ -(v(3)^2+v(2)^2-4-v(1)^2), 2*(2*v(3)+v(2)*v(1)), 2*(v(3)*v(1)-2*v(2));
          -2*(2*v(3)-v(2)*v(1)), -(-4+v(1)^2-v(2)^2+v(3)^2), 2*(2*v(1)+v(3)*v(2));
          2*(2*v(2)+v(3)*v(1)),   2*(-2*v(1)+v(3)*v(2)), (4-v(1)^2-v(2)^2+v(3)^2)];