Submitted on: 05 October 1999.
Revised on: 24 November 1999.
Accepted on: 19 January 2000.
___________________JOURNAL OF COMPUTATIONAL MATHEMATICS
Submitted on: 04 October 2006.
Revised on: 19 January 2007.
Accepted on: 20 February 2007.
___________________JOURNAL OF COMPUTATIONAL MATHEMATICS
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Submitted on: 17 July 2007.
Revised on: 06 October 2007.
Accepted on: 22 October 2007.
___________________JOURNAL OF COMPUTATIONAL MATHEMATICS
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