Recently, a special class of recurrent neural network (termed Zhang neural network, ZNN) has been generalized for solving systems of time-varying nonlinear equations (STVNE), and a resultant continuous (or say, continuous-time) ZNN model has been proposed and analyzed. To generalize the idea for digital computers and numerical algorithms, this paper discretizes the continuous STVNE-solving ZNN using Euler difference and improves the discrete (or say, discretetime) ZNN models by employing Broyden method. Results of various numerical experiments are presented to verify the effectiveness of the proposed discrete ZNN models, especially the Broyden-method aided ones.
Keywords-Broyden method; Zhang neural network; timevarying; systems of nonlinear equations; discrete methods
I. INTRODUCTIONFor the needs of various applications, there have been lots of efficient numerical methods for solving systems of nonlinear equations, with Broyden method [1] being one of them. However, in many real-time applications, systems are dynamical. Those methods aimed for time-invariant systems cannot perform well when applied to time-varying ones.Zhang neural network (ZNN) is an efficient continuous model for solving dynamical problems [2]-[4], and has been proved to be able to solve systems of time-varying nonlinear equations (STVNE) with exponential convergence rate [5]. For numerical implementation, the STVNE-solving continuous ZNN is discretized into two discrete models: DZ-K (discrete ZNN with the system's time-derivative information f t known) and DZ-U (discrete ZNN with the system's timederivative information f t unknown).Similar to Newton method, DZ-K and DZ-U may suffer from problems of computing the inverse of Jacobian matrix. Like Broyden method improving Newton method, this paper improves DZ-K and DZ-U by employing Broyden method [1], producing two new models, DZ-K-B and DZ-U-B, respectively. Finally, results of numerical experiments on the proposed discrete ZNN models are presented with their experimental properties described and concluded.