APPROXIMATING CHI(N) EFFICIENTLY

A fast technique to evaluate x(n) to an accuracy of one part in N for 0.0 less-than-or-equal-to x less-than-or-equal-to 1.0 is discussed. Su ch approximations are useful in several scientific applications. The m ain features of the technique are as follows: Novelty: The fundamental and distinguishing contribution of our technique is the drastic reduc tion in the size of look-up tables used in the evaluation without a co mmensurate loss in performance or accuracy. Generality: The technique presented herein can be used in both hardware and software products de pending on the performance requirements and amount of silicon availabl e. The technique is illustrated more elaborately by discussing its use for computing light intensities in graphics modeling.