Algorithm 743: WAPR--a Fortran routine for calculating real values of the W-function

We implement <italic>W</italic>-function approximation scheme described by Barry et al. A range of tests of the approximations is included so that the code can be assessed on any given machine. Users can calculate <italic>W(x)</italic> by specifying <italic>x</italic> itself or by specifying an offset from −exp(−1), the latter option necessitated by rounding errors that can arise for <italic>x</italic> close to −exp(−1). Results of running the code on a <italic>SUN</italic> workstation are included.