Input                                         
                                                                                                                                                         
                                                                                                                                                         
                                                                                                                                                         
                                                                                                                                                         
                                                                                                           Initialize                                    
                                                                                                                                                         
                                                                                                                                                         
                                                                                                                                                         
                                                                                                                                                         
                                                                                                                                                         
                                                                                                                                                         
                                                                                                                                                         
                                                                                                                                                         
                                                                                                                                                         
                           Randomly select a sample pair                                                                                                 
                                                                                                                                                         
                                                                                                                                                         
                                                                                                                                                         
                                                                                                                                                         
                                                                  Forward propagation                                                                    
                                                                                                                                                         
                                                                                                                                                         
                                                                                                                                                         
                                                                                                                                                         
                                                                             Computing gradient                                                          
                                                                                                                                                         
                                                                                                                                                         
                                                                                                                                                         
                                                                                                                                                         
                                                                                                                                                         
                                                                                                        Back propagation                                 
                                                                                                                                                         
                                                                                                                                                         
                                                                                                                                                         
                                                                                                                                                         
                                                                                                                                                         
                                                                                                           Caculate                                      
                                                                                                                                                         
                                                                                                                                                         
                                                                                                                                                         
                                                                                                                                                         
                                                                                                                                             convergence?
                                                                                                                                                         
                                                                                                                                                         
                                                                                                                                                         
                                                                                                                                                         
                                                                                                           Output