Equator. A function calculator. Equator is a software package that generates numerical values for over 200 mathematical functions. By using the “variable ranging” facility, one can get the values of a function for a given range of a variable, defined by the lower and upper bounds and an increment. Equator has no plotting capability, but to graph the output of a ranged calculation, one can easily transfer the data to graphing software (e.g. Excel). An input variable can be constructed in a general form as x=wt p +k, with the default values w=1, p=1, k=0, corresponding to x=t. Most of the answers are provided with 15-digit precision. The software is able to detect when precision is likely to have been lost and it curtails the output, reporting only the significant digits. The basic formulas for the algorithms used by Equator are available in the book by the same authors [An atlas of functions. With Equator, the atlas function calculator. With CD-ROM. 2nd ed. New York, NY: Springer (2008; Zbl 1167.65001)].