private static void Forward()
{
for (int l = 0; l < L; l++)
{
Z[l + 1] = MatrixMath.Add(MatrixMath.Multiply(W[l], A[l]), b[l]);
A[l + 1] = MatrixMath.F(Z[l + 1], layerFunctions[l + 1], epsilonLeaky, false); //false mean apply function, true means apply function derivative
}
Z[L + 1] = MatrixMath.Add(MatrixMath.Multiply(W[L], A[L]), b[L]); //last layer pre-activation
if (criterion == "MSE") //last layer activation
{
A[L + 1] = Z[L + 1].Clone();
}
else if (criterion == "SoftMax")
{
A[L + 1] = new Matrix(10, 1);
double Denom = MatrixMath.SumExp(Z[L + 1]);
for (int c = 0; c < Z[L + 1].Rows; c++)
{
A[L + 1][c, 0] = Math.Exp(Z[L + 1][c, 0]) / Denom;
}
}
}
private static void Backward(int k)
{
errors[L + 1] = MatrixMath.Subtract(A[L + 1], label); //error at output layer neurons
for (int l = L; l >= 1; l--) // error at hidden layers neurons e[l] = W[l].Transpose * e[l+1]) . F'(Z[l]) where * is matrix multiplication and . is hadamard multiplication
{
errors[l] = MatrixMath.HadamardProduct(MatrixMath.Multiply(MatrixMath.Transpose(W[l]), errors[l + 1]), MatrixMath.F(Z[l], layerFunctions[l], epsilonLeaky, true));
}
for (int l = 0; l <= L; l++)
{
dW[l] = MatrixMath.Multiply(errors[l + 1], MatrixMath.Transpose(A[l]));
db[l] = errors[l + 1];
}
for (int l = 0; l <= L; l++)
{
acc_dW[k][l] = dW[l].Clone();
acc_db[k][l] = db[l].Clone();
//deltaW[l] = MatrixMath.Add(deltaW[l], dW[l]);
//deltab[l] = MatrixMath.Add(deltab[l], db[l]);
}
}