new doc and optical backprop

tests/backpropagation_perf.cpp

@@ -0,0 +1,26 @@
+#include <NeuralNetwork/FeedForward/Network.h>
+
+#include <cassert>
+#include <iostream>
+#include "../include/NeuralNetwork/Learning/BackPropagation.h"
+
+int main() {
+	{	// XOR problem
+		NeuralNetwork::FeedForward::Network n(2);
+		NeuralNetwork::ActivationFunction::Sigmoid a(-1);
+		n.appendLayer(200,a);
+		n.appendLayer(500,a);
+		n.appendLayer(900,a);
+		n.appendLayer(1,a);
+
+		n.randomizeWeights();
+
+		NeuralNetwork::Learning::BackPropagation prop;
+		for(int i=0;i<100;i++) {
+			prop.teach(n,{1,0},{1});
+			prop.teach(n,{1,1},{0});
+			prop.teach(n,{0,0},{0});
+			prop.teach(n,{0,1},{1});
+		}
+	}
+}