Evaluation of functions on microcomputers: exp(x)

AbstractThis paper is a continuation of a study of numerical software for evaluating elementary functions in a microcomputer environment. Here we describe three algorithms for evaluation of the exponential function that are based on rationals, polynomials and coarse table look-up, respectively. Focus is on the design of fast algorithms that preserve full machine precision in small scale machines which use truncated binary fixed point arithmetic with at most a sixteen-bit wordlength. Included in the paper is a comparison of the performance of these algorithms implemented in two contemporary microcomputers