JUN-SEOP SONG 12 [7] J. F. Traub, Iterative Methods for the Solution of Equations , Prentice-Hall, Englewood Cliffs, New Jersey, 1964. [8] S. Weerakoon, T. G. I. Fernando, A variant of Newton’s method with accelerated third-order conver- gence , Appl. Math. Lett. 13 (2000), 87-93. E-mail address : junseopsong@yonsei.ac.kr