1. A tool for making simplified circuit model by adaptive-order multipoint rational Arnoldi method, which contains the following procedures: (a) Input a mesh circuit and values of its parameters; (b) Establish a state matrix of original circuit mode; (c) Input the order of required simplified circuit and acquire the corresponding orthonormal matrix by adaptive-order multipoint rational Arnoldi algorithm; (d) Orthogonally project the state space of the original circuit into the state space of the simplified circuit.