get_partial_outer_product_right Function

  function get_partial_outer_product_right(this, upstream_grad) result(output)
    implicit none
    class(array_type), intent(inout) :: this
    type(array_type), intent(in) :: upstream_grad
    type(array_type) :: output
    logical :: left_is_temporary_local
    type(array_type), pointer :: ptr

    left_is_temporary_local = this%left_operand%is_temporary
    this%left_operand%is_temporary = .false.
    if(this%is_forward)then
       ptr => this%left_operand .outer. upstream_grad
    else
       ! mathematically should be ptr => transpose(upstream_grad) .mmul. this%left_operand
       ! but for how we store vectors, this SHOULD BE equivalent
       ptr => matmul(this%left_operand, upstream_grad)
    end if
    this%left_operand%is_temporary = left_is_temporary_local
    call output%assign_and_deallocate_source(ptr)
  end function get_partial_outer_product_right