_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

The
erfc()
function returns 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.

CONFORMING TO

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

NOTES

The
erfc()
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).

This page is part of release 3.27 of the Linux
man-pages
project.
A description of the project,
and information about reporting bugs,
can be found at
http://www.kernel.org/doc/man-pages/.