Let \(M_n\) be a \(n\)-dimensional manifold and \((\Omega_1, \varphi_1)\), \((\Omega_2,\varphi_2)\) two local charts on \(M_n\) with \(\Omega_1\cap \Omega_2\neq \emptyset\). Then \(\varphi_1 \circ \varphi_2^{-1}\) is called change of charts or transition map of \(\varphi_2(\Omega_1\cap \Omega_2)\) onto \(\varphi_2(\Omega_1\cap \Omega_2)\).