erf(S)                         6 January 1993                         erf(S)


 Name

    erf, erfc - error function and complementary error function

 Syntax


    cc  . . .  -lm


    #include <math.h>

    double erf (x)
    double x;

    double erfc (x)
    double x;


 Description

    The erf function returns the error function of x.

    erfc, which returns 1.0 minus erf(x), is provided because of the extreme
    loss of relative accuracy if erf(x) is called for a large x and the
    result subtracted from 1.0 (for example, for x = 5, 12 places are lost).

 See also

    exp(S)

 Standards conformance

    erf and erfc are conformant with:
    AT&T SVID Issue 2;
    and X/Open Portability Guide, Issue 3, 1989.