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[thirdparty/man-pages.git] / man3 / erf.3

.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
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.\" References consulted:
.\"     Linux libc source code
.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
.\"     386BSD man pages
.\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
.\" Modified 2002-07-27 by Walter Harms
.\" 	(walter.harms@informatik.uni-oldenburg.de)
.\"
.TH ERF 3  2010-09-20 "GNU" "Linux Programmer's Manual"
.SH NAME
erf, erff, erfl, \- error function
.SH SYNOPSIS
.nf
.B #include <math.h>

.BI "double erf(double " x );
.BI "float erff(float " x );
.BI "long double erfl(long double " x );

.fi
Link with \fI\-lm\fP.
.sp
.in -4n
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.in
.sp
.ad l
.BR erf ():
.RS 4
_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE || _ISOC99_SOURCE ||
_POSIX_C_SOURCE\ >=\ 200112L;
.br
or
.I cc\ -std=c99
.RE
.br
.BR erff (),
.BR erfl ():
.RS 4
_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE\ >=\ 600 || _ISOC99_SOURCE ||
_POSIX_C_SOURCE\ >=\ 200112L;
.br
or
.I cc\ -std=c99
.RE
.ad b
.SH DESCRIPTION
The
.BR erf ()
function returns the error function of \fIx\fP, defined
as
.TP
    erf(x) = 2/sqrt(pi)* integral from 0 to x of exp(\-t*t) dt
.SH RETURN VALUE
On success, these functions return the error function of
.IR x ,