double
     erf(double x);

     long double
     erfl(long double x);

     float();

     erff(float x);

     double
     erfc(double x);

     long double
     erfcl(long double x);

     float
     erfcf(float x);

DESCRIPTION

     These functions calculate the error function of x.

     The erf() function calculates the error function of x; where

           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() computes the difference of the error function erf(x) from
     1.0.  This is useful, since for large x use of erfc() avoids loss of pre-
     cision due to cancellation.

SPECIAL VALUES

     erf(+-0) returns +-0.

     erf(+-infinity) returns +-1.

     erfc(-infinity) returns 2.

     erfc(+infinity) returns +0.

SEE ALSO

     math(3)

STANDARDS

     The erf() and erfc() functions conform to ISO/IEC 9899:1999(E).

4.3 Berkeley Distribution      January 30, 2003      4.3 Berkeley Distribution