get_partial_softmax_reverse_left Function

  function get_partial_softmax_reverse_left(this, upstream_grad) result(output)
    !! Get partial derivative of softmax reverse operation
    implicit none
    class(array_type), intent(inout) :: this
    type(array_type), intent(in) :: upstream_grad
    type(array_type) :: output

    type(array_type), pointer :: sum_yg, sum_yu
    type(array_type), pointer :: ptr

    sum_yg => sum(this%left_operand * this%right_operand, dim=this%indices(1))
    sum_yu => sum(this%left_operand * upstream_grad, dim=this%indices(1))

    ptr => upstream_grad * (this%right_operand - sum_yg) - this%right_operand * sum_yu
    call output%assign_and_deallocate_source(ptr)

  end function get_partial_softmax_reverse_left