This is great! I&#x27;m exactly the person that post was intended for, with the limited ML background. I&#x27;m following both Andrew Ng&#x27;s and Richard Socher&#x27;s lectures. I got stuck around chain rule.<p>Speaking of Socher, he mentions in his dissertation about alternatives to using the Sigmoid:<p>&quot;Various other recent nonlinearities exist such as the hard tanh (which is faster to compute) or rectified linear: f(x) = max(0,x) (which does not suffer from the vanishing gradient problem as badly).&quot;<p>I wonder if one of these alternatives would improve on the XOR example? Am hoping to implement some ANNs on a mobile GPU, using iOS + Metal. But 10,000 epochs for the XOR example sounds a bit scary - as in turning an iPhone into a hand warmer.