erfc(3) Library Functions Manual erfc(3)
NAME
erfc, erfcf, erfcl - complementary error function
LIBRARY
Math library (libm, -lm)
SYNOPSIS
#include <math.h>
double erfc(double x);
float erfcf(float x);
long double erfcl(long double x);
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
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 at-
tributes(7).
┌────────────────────────────────────────────┬───────────────┬─────────┐
│Interface │ Attribute │ Value │
├────────────────────────────────────────────┼───────────────┼─────────┤
│erfc(), erfcf(), erfcl() │ Thread safety │ MT-Safe │
└────────────────────────────────────────────┴───────────────┴─────────┘
STANDARDS
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)
Linux man-pages 6.03 2023-02-05 erfc(3)
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