get_partial_add_val Subroutine

  pure subroutine get_partial_add_val(this, upstream_grad, output)
    !! Get partial derivative with respect to left operand
    implicit none
    class(array_type), intent(in) :: this
    real(real32), dimension(:,:), intent(in) :: upstream_grad
    real(real32), dimension(:,:), intent(out) :: output

    if(size(upstream_grad,2).ne.size(output,2))then
       if(size(output,1).eq.1)then
          output(1,1) = sum(upstream_grad)
       else
          output(:,1) = sum(upstream_grad, dim=2)
       end if
    else
       if(size(output,1).eq.1.and.size(output,1).ne.size(upstream_grad,1))then
          output(1,:) = sum(upstream_grad,1)
       else
          output = upstream_grad
       end if
    end if
  end subroutine get_partial_add_val