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1.1 root 1: .\" Copyright (c) 1985 Regents of the University of California.
2: .\" All rights reserved. The Berkeley software License Agreement
3: .\" specifies the terms and conditions for redistribution.
4: .\"
5: .\" @(#)erf.3 6.2 (Berkeley) 5/12/86
6: .\"
7: .TH ERF 3M "May 12, 1986"
8: .UC 6
9: .SH NAME
10: erf, erfc \- error functions
11: .SH SYNOPSIS
12: .nf
13: .B #include <math.h>
14: .PP
15: .B double erf(x)
16: .B double x;
17: .PP
18: .B double erfc(x)
19: .B double x;
20: .fi
21: .SH DESCRIPTION
22: Erf\|(x) returns the error function of x; where
23: .if n \{\
24: .PP
25: erf(x) = 2/sqrt(pi)\(**\|integral from 0 to x of exp(\-t\(**t) dt. \}
26: .if t \{\
27: erf\|(x) :=
28: (2/\(sr\(*p)\|\(is\d\s8\z0\s10\u\u\s8x\s10\d\|exp(\-t\u\s82\s10\d)\|dt. \}
29: .PP
30: Erfc\|(x) returns 1.0\-erf\|(x).
31: .PP
32: The entry for erfc is provided because of the extreme loss
33: of relative accuracy if erf\|(x) is called for large x
34: and the result subtracted from 1.
35: (e.g. for x = 10, 12 places are lost).
36: .SH SEE ALSO
37: math(3M)
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