NAME    [Toc]    [Back]

     erf, erff, erfc, erfcf - error function operators

SYNOPSIS    [Toc]    [Back]

     #include <math.h>

     double
     erf(double x);

     float
     erff(float x);

     double
     erfc(double x);

     float
     erfcf(float x);

DESCRIPTION    [Toc]    [Back]

     These functions calculate the error function of x.

     The erf() calculates the error function of x, and the erff()
function is
     a  single precision version of erf().  The error function is
defined as:

           erf(x) = 2/sqrt(pi)*integral from 0 to x of  exp(-t*t)
dt.

     The erfc() function calculates the complementary error function of x;
     that is erfc() subtracts the result of  the  error  function
erf(x) from
     1.0.   This  is  useful, since for large x places disappear.
The erfcf()
     function is a single precision version of erfc().

SEE ALSO    [Toc]    [Back]

     math(3)

HISTORY    [Toc]    [Back]

     The erf() and erfc() functions appeared in 4.3BSD.

OpenBSD     3.6                          April      20,      1991