This section introduces two mathematical functions that work like switches. Unlike most of the Excel functions (such as sine), which deliver a result value from an original value with no surprises, the saltus functions recognize only two result values:
1. Depending on the amount of the original value, they toggle between 0 and 1. The DELTA() function only recognizes one instance for which it returns
1. Otherwise, it always returns
0. The GESTEP() function, however, continuously toggles between
1, when the original value reaches or crosses a fixed minimum (a threshold).
The Dirac delta function δ(x) is the mathematical ancestor of these Excel functions. Like the two Excel functions, it belongs to the saltus functions. ...