Khurul Wardati
(1), Indah Emilia Wijayanti
(2), Sri Wahyuni
(3)
(1)
Departement of Mathematics UIN Sunan Kalijaga Yogyakarta, Indonesia,
(2)
Department of Mathematics, UGM, Yogyakarta, Indonesia,
(3)
Department of Mathematics, UGM, Yogyakarta, Indonesia