# Classification accuracy
	def accuracy(pred, gt):
    	return np.sum(pred == gt) / float(pred.shape[0])

	layer2_err = Ytr - layer2
    layer2_delta = layer2_err * sigmoid(layer2_err, True)

    layer1_err = layer2_delta.dot(weights1.T)
    layer1_delta = layer1_err * sigmoid(layer1, True)

    weights0 += lr * Xtr.T.dot(layer1_delta)
    weights1 += lr * layer1.T.dot(layer2_delta)