On the basic operations of interval multiple-precision arithmetic with center-radius form

概要

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Multiple-precision arithmetic with interval variables has been developed for computation with guaranteed high accuracy. There are several computer program packages which deal with interval variables of the inf-sup form, e.g. MPFI, etc. On the other hand, it is impressed by INTLAB that interval multiple-precision arithmetic using the center-radius form has advantages on memory size and computing time. However, arithmetic of the center-radius form sometimes makes the radius of an interval larger than the inf-sup form does, which would be one of the reasons why there is no practical program package for interval multiple-precision arithmetic with the center-radius form. The authors intend to establish a computer program package for multiple-precision arithmetic using intervals of the center-radius form which is still under construction. The present paper treats the problem of the center-radius form about the expansion of radii caused by the fundamental rules and the operation of square root. We propose several methods for calculation of multiplication, division, and square root, among which one can choose an appropriate method according to ones situation. Theoretical consideration and numerical examples are given for these methods.