This work is a striking compendium of results concerning the design of a CORDIC coprocessor that supports, independently, both variable precision (VP) and interval (I) arithmetic. It represents an important milestone in the authors’ research, which stretches back ten years or more. Although coprocessors for basic VP and I arithmetic operations can be found in the literature, with elementary functions computed by polynomial approximation, the seminal contribution of this work is the extension to elementary function computation using the CORDIC algorithm.

Besides presenting a thorough treatment of the theory underlying their solution, the authors include considerable discussion on reducing its actual computation time, chiefly by expediting the rotation of an interval vector through an interval angle, and by omitting the processing of leading zero words. Though the reader might wish for more thorough timing comparisons with other hardware techniques, the results that are presented are quite promising, suggesting improvements that become more dramatic as the maximum precision increases, for nominal hardware cost.

This is a commendable piece of work, which should be of great interest to the builders of arithmetic coprocessors.