该代码为基于BP神经网络的预测算法。对于复杂的非线性系统，难以用数学方法准确建模，在这种情况下，可以建立BP神经网络表达这些非线性系统。(The code is a prediction algorithm based on BP neural network. It is difficult for complex nonlinear systems to be modeled accurately by mathematical methods. In this case, BP neural networks can be established to express these nonlinear systems.)