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erfc(3) — Linux manual page

NAME \|LIBRARY \|SYNOPSIS \|DESCRIPTION \|RETURN VALUE \|ERRORS \|ATTRIBUTES \|STANDARDS \|HISTORY \|NOTES \|SEE ALSO \|COLOPHON

erfc(3)                  Library Functions Manualerfc(3)

NAME top

       erfc, erfcf, erfcl - complementary error function

LIBRARY top

       Math library (libm,-lm)

SYNOPSIS top

#include <math.h>double erfc(doublex);float erfcf(floatx);long double erfcl(long doublex);   Feature Test Macro Requirements for glibc (seefeature_test_macros(7)):erfc():           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE               || /* Since glibc 2.19: */ _DEFAULT_SOURCE               || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCEerfcf(),erfcl():           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L               || /* Since glibc 2.19: */ _DEFAULT_SOURCE               || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

DESCRIPTION top

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

RETURN VALUE top

       On success, these functions return the complementary error       function ofx, a value in the range [0,2].       Ifx is a NaN, a NaN is returned.       Ifx is +0 or -0, 1 is returned.       Ifx is positive infinity, +0 is returned.       Ifx 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

       Seemath_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 seterrno.

ATTRIBUTES top

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

STANDARDS top

       C11, POSIX.1-2008.

HISTORY top

       C99, POSIX.1-2001.       The variant returningdouble also conforms to SVr4, 4.3BSD.

NOTES top

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

COLOPHON top

       This page is part of theman-pages (Linux kernel and C library       user-space interface documentation) project.  Information about       the project can be found at        ⟨https://www.kernel.org/doc/man-pages/⟩.  If you have a bug report       for this manual page, see       ⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.       This page was obtained from the tarball man-pages-6.15.tar.gz       fetched from       ⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on       2025-08-11.  If you discover any rendering problems in this HTML       version of the page, or you believe there is a better or more up-       to-date source for the page, or you have corrections or       improvements to the information in this COLOPHON (which isnot       part of the original manual page), send a mail to       man-pages@man7.orgLinux man-pages 6.15            2025-05-17erfc(3)

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