Adaptive Growing Randomized Neural Networks for Solving Partial Differential Equations

Abstract: Randomized neural network (RNN) methods have been proposed for solving various partial differential equations (PDEs), demonstrating high accuracy and efficiency. However, initializing the fixed parameters remains a challenging issue. Additionally, RNNs often struggle to solve PDEs with sharp or discontinuous solutions. In this paper, we propose a novel approach called Adaptive Growing Randomized Neural Network (AG-RNN) to address these challenges. First, we establish a parameter initialization strategy based on frequency information to construct the initial RNN. After obtaining a numerical solution from this initial network, we use the residual as an error indicator. Based on the error indicator, we introduce growth strategies that expand the neural network, making it wider and deeper to improve the accuracy of the numerical solution. A key feature of AG-RNN is its adaptive strategy for determining the weights and biases of newly added neurons, enabling the network to expand in both width and depth without requiring additional training. Instead, all weights and biases are generated constructively, significantly enhancing the network's approximation capabilities compared to conventional randomized neural network methods. In addition, a domain splitting strategy is introduced to handle the case of discontinuous solutions. Extensive numerical experiments are conducted to demonstrate the efficiency and accuracy of this innovative approach.