table of contents
ERF(3) | Linux Programmer's Manual | ERF(3) |
NAME¶
erf, erff, erfl, - error function
SYNOPSIS¶
#include <math.h> double erf(double x); float erff(float x); long double erfl(long double x);
Link with -lm.
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
erf():
or cc -std=c99
erff(), erfl():
or cc -std=c99
DESCRIPTION¶
The erf() function returns the error function of x, defined as
RETURN VALUE¶
On success, these functions return the error function of x, a value in the range [-1, 1].
If x is a NaN, a NaN is returned.
If x is +0 (-0), +0 (-0) is returned.
If x is positive infinity (negative infinity), +1 (-1) is returned.
If x is subnormal, a range error occurs, and the return value is 2*x/sqrt(pi).
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 (x 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.
SEE ALSO¶
COLOPHON¶
This page is part of release 3.53 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/.
2010-09-20 | GNU |