The “relative” function EXPRL is useful for accurately computing ex ‑ 1 near x = 0. Computing ex ‑ 1 using EXP(X) ‑ 1 near x = 0 is subject to large cancellation errors.

Similarly, ALNREL can be used to accurately compute ln(x + 1) near x = 0. Using the routine ALOG to compute ln(x + 1) near x = 0 is subject to large cancellation errors in the computation of 1 + X.