Section (3) erf
erf, erff, erfl — error function
||long double x
These functions return the error function of
x, defined as
- erf(x) = 2/sqrt(pi)* integral from 0 to x of exp(−t*t) dt
On success, these functions return the error function of
x, a value in the
range [−1, 1].
x is a NaN, a
NaN is returned.
x is +0
(−0), +0 (−0) is returned.
x is positive
infinity (negative infinity), +1 (−1) is returned.
x is subnormal,
a range error occurs, and the return value is
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(
An underflow floating-point exception (
FE_UNDERFLOW) is raised.
These functions do not set
For an explanation of the terms used in this section, see attributes(7).
C99, POSIX.1-2001, POSIX.1-2008.
The variant returning double also conforms to SVr4, 4.3BSD.
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Linux libc source code
Lewine_zsingle_quotesz_s _POSIX Programmer_zsingle_quotesz_s Guide_ (O_zsingle_quotesz_Reilly & Associates, 1991)
386BSD man pages
Modified 1993-07-24 by Rik Faith (faithcs.unc.edu)
Modified 2002-07-27 by Walter Harms