Abstract
In Dai and Wen (Numer. Algor.
69, 337–341
2015), some improvements have been presented in the proof of Theorem 2 and Theorem 4 in Andrei (Numer. Algor.
47, 143–156
2008). However, due to incorrect inequalities used, the reasoning proof of Theorem 2.1 in Dai and Wen (Numer. Algor.
69, 337–341
2015) is incorrect. Moreover, the assumption on 0 <
c1 ≤
𝜃k < 1 of Theorem 2.1 cannot be deleted in Dai and Wen (Numer. Algor.
69, 337–341
2015). In this paper, the necessary corrections are made. Finally, another version of the proof process of Theorem 3.1 in (Numer. Algor.
69, 337–341
2015) is given. Throughout, we use the same notations and equation numbers as in Dai and Wen (Numer. Algor.
69, 337–341
2015), Andrei (Numer. Algor.
47, 143–156
2008).