FIX: added data-set normalization to the example net_test_1 to prevent 'nan'...

FIX: added data-set normalization to the example net_test_1 to prevent 'nan' results returned by Gradient descent method.

src/examples/net_test_1.cpp

@@ -141,5 +141,10 @@ int main() {
     net.randomize_parameters();
     optimize_via_gradient_descent( net, mse );
 
+    /* Normalize data to prevent 'nan' results */
+    ds.normalize();
+    net.randomize_parameters();
+    optimize_via_gradient_descent(net, mse);
+
     return 0;
 }