ERFC(3) - man page online | library functions

Complementary error function.

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 These functions return 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.
ATTRIBUTES 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 C99, POSIX.1-2001, POSIX.1-2008. The variant returning double also conforms to SVr4, 4.3BSD.
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).
SEE ALSO cerf(3), erf(3), exp(3)
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GNU 2015-04-19 ERFC(3)
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erfc(3) referred by erf(3)
refer to attributes(7) | cerf(3) | erf(3) | exp(3) | feature_test_macros(7) | math_error(7)