erfc, erfcf, erfcl - complementary error function

Attributes

       For an explanation of the terms used in this section, see attributes(7).
       ┌─────────────────────────────────────────────────────────────────────────────┬───────────────┬─────────┐
       │ Interface                                                                   │ Attribute     │ Value   │
       ├─────────────────────────────────────────────────────────────────────────────┼───────────────┼─────────┤
       │ erfc(), erfcf(), erfcl()                                                    │ Thread safety │ MT-Safe │
       └─────────────────────────────────────────────────────────────────────────────┴───────────────┴─────────┘

Description

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

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.

History

       C99, POSIX.1-2001.

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

Library

       Math library (libm, -lm)

Name

       erfc, erfcf, erfcl - complementary error function

Notes

       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).

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.

Standards

       C11, POSIX.1-2008.

Synopsis

#include<math.h>doubleerfc(doublex);floaterfcf(floatx);longdoubleerfcl(longdoublex);

   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 <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

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