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ERFC(3)                    Linux Programmer's Manual                   ERFC(3)

NAME
       erfc, erfcf, erfcl - complementary error function
SYNOPSIS
       #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)):
       erfc():
           _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE || _ISOC99_SOURCE ||
           _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
DESCRIPTION
       The erfc() function returns the complementary error function of x, that
       is, 1.0 - erf(x).
RETURN VALUE
       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.
ERRORS
       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.
CONFORMING TO
       C99, POSIX.1-2001.  The variant returning double also conforms to SVr4,
       4.3BSD.
NOTES
       The erfc() 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).
SEE ALSO
       cerf(3), erf(3), exp(3)
COLOPHON
       This  page  is  part of release 3.53 of the Linux man-pages project.  A
       description of the project, and information about reporting  bugs,  can
       be found at http://www.kernel.org/doc/man-pages/.

GNU                               2010-09-20                           ERFC(3)