On the Derivatives of the Sigmoid
eecs.ceas.uc.edu › ~aminai › papersAn interesting property of the sigmoid is that the de- rivatives of y can be written in terms of y and w only. The first derivative ofy with respect to yj is given by: e -wx O.(1 ) = dy dx w. ( 1 + e-'x) 2 wy( - y). (4) The second derivative can be obtained from this by differentiating again with respect to x.