train_epochs Subroutine

  subroutine train_epochs(self, x, y, eta, num_epochs, batch_size)
    !! Trains for num_epochs epochs with mini-bachtes of size equal to batch_size.
    class(network_type), intent(in out) :: self
    integer(ik), intent(in) :: num_epochs, batch_size
    real(rk), intent(in) :: x(:,:), y(:,:), eta

    integer(ik) :: i, n, nsamples, nbatch
    integer(ik) :: batch_start, batch_end

    real(rk) :: pos

    nsamples = size(y, dim=2)
    nbatch = nsamples / batch_size

    epochs: do n = 1, num_epochs
      batches: do i = 1, nbatch
      
        !pull a random mini-batch from the dataset  
        call random_number(pos)
        batch_start = int(pos * (nsamples - batch_size + 1))
        if (batch_start == 0) batch_start = 1
        batch_end = batch_start + batch_size - 1
   
        call self % train(x(:,batch_start:batch_end), y(:,batch_start:batch_end), eta)
       
      end do batches
    end do epochs

  end subroutine train_epochs