#include <math.h>

       double erfc(double x);
       float erfcf(float x);
       long double erfcl(long double x);

       Link with -lm.

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

           _POSIX_C_SOURCE >= 200112L;
           or cc -std=c99
       erfcf(), erfcl():
           _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600||
           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L;
           or cc -std=c99

       These  functions return the complementary error function of x, that is,
       1.0 - erf(x).

       On success, these functions return the complementary error function  of
       x, a value in the range [0,2].

       If x is a NaN, a NaN is returned.

       If x is +0 or -0, 1 is returned.

       If x is positive infinity, +0 is returned.

       If x is negative infinity, +2 is returned.

       If  the  function  result  underflows  and  produces an unrepresentable
       value, the return value is 0.0.

       If the function result underflows but produces a  representable  (i.e.,
       subnormal) value, that value is returned, and a range error occurs.

       See  math_error(7) for information on how to determine whether an error
       has occurred when calling these functions.

       The following errors can occur:

       Range error: result underflow (result is subnormal)
              An underflow floating-point exception (FE_UNDERFLOW) is raised.

       These functions do not set errno.

       For  an  explanation  of  the  terms  used   in   this   section,   see

       The  erfc(),  erfcf(),  and erfcl() functions are provided to avoid the
       loss accuracy that would occur for the calculation 1-erf(x)  for  large
       values of x (for which the value of erf(x) approaches 1).

       cerf(3), erf(3), exp(3)

       This  page  is  part of release 4.04 of the Linux man-pages project.  A
       description of the project, information about reporting bugs,  and  the
       latest     version     of     this    page,    can    be    found    at

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