Evaluates the real error function erf ( x ). Using a keyword, the inverse error function erf –1(x) can be evaluated.

x—Expression for which the error function is to be evaluated.

result—The value of the error function erf(x).

Double—If present and nonzero, double precision is used.

Inverse—Evaluates the real inverse error function erf–1(x). The inverse error function is defined only for –1 < x < 1.

The error function erf(x) is defined below:

All values of x are legal. The inverse error function y = erf –1(x) is such that x = erf (y).