三道题，包括1：用多层感知器（MLP）神经网络误差反向传播（BP）算法实现异或问题:2：用奇阶互补法设计两带滤波器组(高、低通互补)，进而实现四带滤波器组 3：估计其功率谱-Three questions, including: 1 using multilayer perceptron ( MLP ) neural network and error back propagation ( BP ) algorithm to realize the XOR problem: 2: the odd order complementary method in the design of two-band filters ( complementary high, low pass ), so as to realize the four band filter group 3: to estimate the power spectrum