Back-propagation-Neural-Network using neural newwork with back propagation learning function : y = x1^2 +x2^2 Neural: 10, lr:1, momenton: 0 Neural: 10, lr:0.01, momenton: 0.9 See result https://github.com/LiaoSteve/Back-propagation-Neural-Network/blob/master/BPNN.docx