NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | ATTRIBUTES | CONFORMING TO | NOTES | SEE ALSO | COLOPHON

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

NAME         top

       erfc, erfcf, erfcl - complementary error function

SYNOPSIS         top

       #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():
           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE
               || /* Since glibc 2.19: */ _DEFAULT_SOURCE
               || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
       erfcf(), erfcl():
           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
               || /* Since glibc 2.19: */ _DEFAULT_SOURCE
               || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

DESCRIPTION         top

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

RETURN VALUE         top

       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         top

       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.

ATTRIBUTES         top

       For an explanation of the terms used in this section, see
       attributes(7).

       ┌─────────────────────────┬───────────────┬─────────┐
       │Interface                Attribute     Value   │
       ├─────────────────────────┼───────────────┼─────────┤
       │erfc(), erfcf(), erfcl() │ Thread safety │ MT-Safe │
       └─────────────────────────┴───────────────┴─────────┘

CONFORMING TO         top

       C99, POSIX.1-2001, POSIX.1-2008.

       The variant returning double also conforms to SVr4, 4.3BSD.

NOTES         top

       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).

SEE ALSO         top

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

COLOPHON         top

       This page is part of release 4.07 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
       https://www.kernel.org/doc/man-pages/.

GNU                              2016-03-15                          ERFC(3)