NEURONS AS FUNCTIONS S(x) X -00 0 + +00 Fig.1 s(x)is a bounded monotone-nondecreasing function of x If c+,we get threshold signal function (dash line) Which is piecewise differentiableNEURONS AS FUNCTIONS S(x) x -∞ - 0 + +∞ Fig.1 s(x) is a bounded monotone-nondecreasing function of x If c→+∞，we get threshold signal function (dash line), Which is piecewise differentiable