I’m trying to write my own NeuralNetwork, and I use my own Matrix2D class for the operations. I’m trying to write out the values of the neural neutworks first weigth matrix but I get an error like: 161|error: invalid use of member ‘Matrix2D NeuralNewtork::first_hidden_weights()’ (did you forget the ‘&’ ?)|
#include <iostream>
#include <stdlib.h>
#include <time.h>
using namespace std;
float RandomNumber()
{
return ((((double) rand() / (RAND_MAX))*2)-1);
}
class Matrix2D{
public:
int rows;
int columns;
float **matrix;
Matrix2D(int x, int y){
rows = x;
columns = y;
matrix = new float*[rows];
for (int i = 0; i < rows; i++) {
matrix[i] = new float[columns];
}
for (int i = 0; i < rows; i++) {
for (int j = 0; j < columns; j++) {
matrix[i][j] = 0;
}
}
}
Matrix2D randomizeMatrix(){
Matrix2D result(rows, columns);
for (int i = 0; i < rows; i++) {
for (int j = 0; j < columns; j++) {
matrix[i][j] = RandomNumber();
}
}
return result;
}
static Matrix2D scalarMultiply(Matrix2D x, float y){
Matrix2D result(x.rows, x.columns);
for (int i = 0; i < x.rows; i++) {
for (int j = 0; j < x.columns; j++) {
result.matrix[i][j] = x.matrix[i][j] * y;
}
}
return result;
}
static Matrix2D scalarAddition(Matrix2D x, float y){
Matrix2D result(x.rows, x.columns);
for (int i = 0; i < x.rows; i++) {
for (int j = 0; j < x.columns; j++) {
result.matrix[i][j] = x.matrix[i][j] + y;
}
}
return result;
}
static Matrix2D scalarSubstraction(Matrix2D x, float y){
Matrix2D result(x.rows, x.columns);
for (int i = 0; i < x.rows; i++) {
for (int j = 0; j < x.columns; j++) {
result.matrix[i][j] = x.matrix[i][j] - y;
}
}
return result;
}
static Matrix2D matrixAddition(Matrix2D x, Matrix2D y){
Matrix2D result(x.rows, x.columns);
for (int i = 0; i < x.rows; i++) {
for (int j = 0; j < x.columns; j++) {
result.matrix[i][j] = x.matrix[i][j] + y.matrix[i][j];
}
}
return result;
}
static Matrix2D matrixTranspose(Matrix2D x){
Matrix2D result(x.columns, x.rows);
for (int i = 0; i < x.rows; i++) {
for (int j = 0; j < x.columns; j++) {
result.matrix[j][i] = x.matrix[i][j];
}
}
return result;
}
static Matrix2D matrixMultiplication(Matrix2D x, Matrix2D y){
Matrix2D result(x.rows, y.columns);
for (int i = 0; i < result.rows; i++) {
for (int j = 0; j < result.columns; j++) {
float sum = 0;
for (int k = 0; k < x.columns; i++) {
sum += x.matrix[i][k] * y.matrix[k][j];
}
result.matrix[i][j] = sum;
}
}
return result;
}
void printMatrix(){
for (int i = 0; i < rows; i++) {
for (int j = 0; j < columns; j++) {
cout << matrix[i][j] << " ";
}
cout << endl;
}
cout << endl;
}
};
class NeuralNewtork{
public:
int numberof_input_nodes;
int numberof_hidden_layers;
int numberof_hidden_nodes;
int numberof_output_nodes;
Matrix2D first_hidden_weights();
Matrix2D* hidden_weigths();
Matrix2D output_weights();
Matrix2D* hidden_biases();
Matrix2D output_biases();
NeuralNewtork(int input_nodes, int hidden_layers, int hidden_nodes, int output_nodes){
numberof_input_nodes = input_nodes;
numberof_hidden_layers = hidden_layers;
numberof_hidden_nodes = hidden_nodes;
numberof_output_nodes = output_nodes;
Matrix2D first_hidden_weights(hidden_nodes, input_nodes);
first_hidden_weights.randomizeMatrix();
Matrix2D* hidden_weigths[numberof_hidden_layers-1];
for (int i=0; i<numberof_hidden_layers-1; i++){
hidden_weigths[i] = new Matrix2D(numberof_hidden_nodes, numberof_hidden_nodes);
hidden_weigths[i]->randomizeMatrix();
}
Matrix2D output_weights(numberof_output_nodes, numberof_hidden_nodes);
output_weights.randomizeMatrix();
Matrix2D* hidden_biases[numberof_hidden_layers];
for (int i=0; i<numberof_hidden_layers; i++){
hidden_biases[i] = new Matrix2D(numberof_hidden_nodes, 1);
hidden_biases[i]->randomizeMatrix();
}
Matrix2D output_biases(numberof_output_nodes, 1);
output_biases.randomizeMatrix();
}
Matrix2D feedForward(Matrix2D input){
}
};
int main()
{
srand (time(0));
//Matrix2D myMatrix(3,7);
//myMatrix.randomizeMatrix();
//myMatrix.printMatrix();
NeuralNewtork nn(4, 3, 5, 1);
nn.first_hidden_weights.printMatrix(); //<=This line gives the error:
return 0;
}
I’m trying to print out the first_hidden_weight Matrix2D obejcts matrix component to see if my code is working the way it’s intended, but I get an error when I try to access that variable.
>Solution :
The first problem is that you defined all your weights as zero-argument functions that return a Matrix2D as opposed to member variables. Drop the ().
Secondly, your constructor creates and initializes shadow variables, which are completely decoupled from your member variables.
Use the = operator to explicitly initialize them:
first_hidden_weights = Matrix2D(hidden_nodes, input_nodes);
For the hidden_weights and hidden_biases members, I suggest you use std::vector<Matrix2D>. This automates memory management and gives you a bunch of handy methods. You might initialize hidden_weights like so:
hidden_weights.reserve(numberof_hidden_layers-1);
for (int i=0; i<numberof_hidden_layers-1; i++){
hidden_weights.push_back(Matrix2D(numberof_hidden_nodes, numberof_hidden_nodes)); // or use emplace_back
hidden_weights.back().randomizeMatrix();
}
Finally, since you seem to call randomizeMatrix a lot after construction, consider making an explicit constructor that automatically randomizes:
enum class Randomize { Randomize };
class Matrix2D {
...
Matrix2D(int x, int y, Randomize)
: Matrix2D(x, y) { // delegate to the simple constructor
randomizeMatrix();
}
...
};
You can then simply write something like Matrix2D(x, y, Randomize).