erf(3M)

NAME

     erf, erfc - error and complementary error functions

SYNOPSIS

     cc [ flag ... ] file ... -lm [ library ... ]
     #include <math.h>

     double erf(double x);

     double erfc(double x);

DESCRIPTION

     The erf() function computes the error function of x, defined
     as:

     2/sqrt(pi)\(**\|integral from 0 to x of exp(\-t\(**t) dt

     The erfc() function computes 1.0 - erf(x).

RETURN VALUES

     Upon successful completion,  erf()  and  erfc()  return  the
     value  of  the  error function and complementary error func-
     tion, respectively.

     If x is NaN, NaN is returned.

ERRORS

     No errors will occur.

USAGE

     The erfc() function is provided because of the extreme  loss
     of relative accuracy if erf(x) is called for large x and the
     result subtracted from 1.0.

ATTRIBUTES

     See attributes(5) for descriptions of the  following  attri-
     butes:

     ____________________________________________________________
    |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
    |_____________________________|_____________________________|
    | MT-Level                    | MT-Safe                     |
    |_____________________________|_____________________________|

SEE ALSO

     isnan(3M), attributes(5)