ERF(3)

NAME
1.14 `erf', `erff', `erfc', `erfcf'--error function

SYNOPSIS
     #include <math.h>
     double erf(double X);
     float erff(float X);
     double erfc(double X);
     float erfcf(float X);

DESCRIPTION
`erf' calculates an approximation to the "error function", which estimates the probability that an observation will fall within X standard deviations of the mean (assuming a normal distribution).
   `erfc' calculates the complementary probability; that is, `erfc(X)' is `1 - erf(X)'. `erfc' is computed directly, so that you can use it to avoid the loss of precision that would result from subtracting large probabilities (on large X) from 1.
   `erff' and `erfcf' differ from `erf' and `erfc' only in the argument and result types.

RETURNS
For positive arguments, `erf' and all its variants return a probability--a number between 0 and 1.

PORTABILITY
None of the variants of `erf' are ANSI C.

SEE ALSO
erf is part of the library. The full documentation for is maintained as a Texinfo manual. If info and are properly installed at your site, the command

    info

will give you access to the complete manual.