quite the same as you can see so what they propose is the following let's send all the data points or in that case all the data points in a particular mini-batch let's send them through the function and let's calculate their linearizations so the linearization is nothing else than you send them through the network to obtain the F value for the x value and then you calculate the gradient with respect to the input now you have to get used to this a bit because usually we calculate the gradient with respect to the weight but