usr/src/lib/libm/common_source/erf.3

From Prof. Kahan at UC at Berkeley
.\" Copyright (c) 1985 Regents of the University of California.
.\" All rights reserved.  The Berkeley software License Agreement
.\" specifies the terms and conditions for redistribution.
.\"
.\"	@(#)erf.3	6.1 (Berkeley) %G%
.\"
.TH ERF 3M  ""
.UC 6
.SH NAME
erf, erfc \- error functions
.SH SYNOPSIS
.nf
.B #include <math.h>
.PP
.B double erf(x)
.B double x;
.PP
.B double erfc(x)
.B double x;
.fi
.SH DESCRIPTION
Erf\|(x) returns the error function of x; where
.if n \{\
.PP
erf(x) = 2/sqrt(pi)\(**\|integral from 0 to x of exp(\-t\(**t) dt. \}
.if t \{\
erf\|(x) :=
(2/\(sr\(*p)\|\(is\d\s8\z0\s10\u\u\s8x\s10\d\|exp(\-t\u\s82\s10\d)\|dt. \}
.PP
Erfc\|(x) returns 1.0\-erf\|(x).
.PP
The entry for erfc is provided because of the extreme loss
of relative accuracy if erf\|(x) is called for large x
and the result subtracted from 1.
(e.g. for x = 10, 12 places are lost).
.SH SEE ALSO
intro(3M)
Commit	Line	Data
	1	From Prof. Kahan at UC at Berkeley
	2	.\" Copyright (c) 1985 Regents of the University of California.
	3	.\" All rights reserved. The Berkeley software License Agreement
	4	.\" specifies the terms and conditions for redistribution.
	5	.\"
	6	.\" @(#)erf.3 6.1 (Berkeley) %G%
	7	.\"
	8	.TH ERF 3M ""
	9	.UC 6
	10	.SH NAME
	11	erf, erfc \- error functions
	12	.SH SYNOPSIS
	13	.nf
	14	.B #include <math.h>
	15	.PP
	16	.B double erf(x)
	17	.B double x;
	18	.PP
	19	.B double erfc(x)
	20	.B double x;
	21	.fi
	22	.SH DESCRIPTION
	23	Erf\\|(x) returns the error function of x; where
	24	.if n \{\
	25	.PP
	26	erf(x) = 2/sqrt(pi)\(\\|integral from 0 to x of exp(\-t\(t) dt. \}
	27	.if t \{\
	28	erf\\|(x) :=
	29	(2/\(sr\(*p)\\|\(is\d\s8\z0\s10\u\u\s8x\s10\d\\|exp(\-t\u\s82\s10\d)\\|dt. \}
	30	.PP
	31	Erfc\\|(x) returns 1.0\-erf\\|(x).
	32	.PP
	33	The entry for erfc is provided because of the extreme loss
	34	of relative accuracy if erf\\|(x) is called for large x
	35	and the result subtracted from 1.
	36	(e.g. for x = 10, 12 places are lost).
	37	.SH SEE ALSO
	38	intro(3M)