An exponentially-fitted explicit Runge-Kutta method is constructed, which e
xactly integrates differential initial-value problems whose solutions are l
inear combinations of functions of the form exp(omega x) and exp(-omega x)
(omega is an element of R or iR); this method is compared to a previously c
onstructed method of Simos. Numerical experiments show the efficiency of th
e new method. (C) 1999 Elsevier Science B.V. All rights reserved.