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| Commit | Line | Data |
|---|---|---|
| f984ed4a | 1 | From Prof. Kahan at UC at Berkeley |
| f9628029 KM |
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 | |
| f984ed4a MAN |
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 | |
| e4b02bf2 MAN |
23 | Erf\|(x) returns the error function of x; where |
| 24 | .if n \{\ | |
| f984ed4a | 25 | .PP |
| e4b02bf2 MAN |
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. \} | |
| f984ed4a | 30 | .PP |
| e4b02bf2 | 31 | Erfc\|(x) returns 1.0\-erf\|(x). |
| f984ed4a | 32 | .PP |
| e4b02bf2 MAN |
33 | The entry for erfc is provided because of the extreme loss |
| 34 | of relative accuracy if erf\|(x) is called for large x | |
| f984ed4a | 35 | and the result subtracted from 1. |
| e4b02bf2 | 36 | (e.g. for x = 10, 12 places are lost). |
| f984ed4a MAN |
37 | .SH SEE ALSO |
| 38 | intro(3M) |