main_loop.cpp

int main(int argc, const char * argv[]) {    
    for (unsigned i = 0; i != 50; ++i) {        
        vector<float> pred = sigmoid(dot(X, W, 4, 4, 1 ) );
        vector<float> pred_error = y - pred;       
        vector<float> pred_delta = pred_error * sigmoid_d(pred);       
        vector<float> W_delta = dot(transpose( &X[0], 4, 4 ), pred_delta, 4, 4, 1);      
        W = W + W_delta;
    };
    return 0;
}