erf(3M)                                                   erf(3M)



     NAME
          erf, erfc - error function and complementary error function

     SYNOPSIS
          #include <math.h>

          double erf(x)
          double x;

          double erfc(x)
          double x;

     DESCRIPTION
          The erf function returns the error function of x (the pre-
          cise formula is available in at standard calculus text).

          erfc, which returns 1.0 - erf(x), 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 (e.g. for x = 5,
          12 places are lost).

     SEE ALSO
          exp(3M).
































     April, 1990                                                     1