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1.\" Copyright (c) 1985, 1991 Regents of the University of California.
2.\" All rights reserved.
3.\"
4.\" Redistribution and use in source and binary forms, with or without
5.\" modification, are permitted provided that the following conditions
6.\" are met:
7.\" 1. Redistributions of source code must retain the above copyright
8.\" notice, this list of conditions and the following disclaimer.
9.\" 2. Redistributions in binary form must reproduce the above copyright
10.\" notice, this list of conditions and the following disclaimer in the
11.\" documentation and/or other materials provided with the distribution.
12.\" 3. All advertising materials mentioning features or use of this software
13.\" must display the following acknowledgement:
14.\" This product includes software developed by the University of
15.\" California, Berkeley and its contributors.
16.\" 4. Neither the name of the University nor the names of its contributors
17.\" may be used to endorse or promote products derived from this software
18.\" without specific prior written permission.
19.\"
20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30.\" SUCH DAMAGE.
31.\"
32.\" from: @(#)sqrt.3 6.4 (Berkeley) 5/6/91
33.\" $FreeBSD: head/lib/msun/man/sqrt.3 84306 2001-10-01 16:09:29Z ru $
33.\" $FreeBSD: head/lib/msun/man/sqrt.3 84881 2001-10-13 12:23:23Z bde $
34.\"
35.Dd May 6, 1991
36.Dt SQRT 3
37.Os
38.Sh NAME
39.Nm cbrt ,
40.Nm cbrtf ,
41.Nm sqrt ,
42.Nm sqrtf
43.Nd cube root and square root functions
44.Sh LIBRARY
45.Lb libm
46.Sh SYNOPSIS
47.In math.h
48.Ft double
49.Fn cbrt "double x"
50.Ft float
51.Fn cbrtf "float x"
52.Ft double
53.Fn sqrt "double x"
54.Ft float
55.Fn sqrtf "float x"
56.Sh DESCRIPTION
57The
58.Fn cbrt
59and the
60.Fn cbrtf
61functions compute
62the cube root of
63.Ar x .
64.Pp
65The
66.Fn sqrt
67and the
68.Fn sqrtf
69functions compute the
70non-negative square root of x.
71.Sh RETURN VALUES
72The
73.Fn cbrt
74and the
75.Fn cbrtf
76functions return the requested cube root.
77The
78.Fn sqrt
79and the
80.Fn sqrtf
81functions return the requested square root
82unless an error occurs.
83On the
84.Tn VAX
85or
86.Tn Tahoe
87processor an attempt to take the
88.Fn sqrt
89of negative
90.Fa x
91causes an error; in this event,
92the global variable
93.Va errno
94is set to
95.Er EDOM
96and a reserved operand fault is generated.
97.Sh ERROR (due to Roundoff etc.)
98The
99.Fn cbrt
100function
101is accurate to within 0.7
102.Em ulps .
103.Pp
104The
105.Fn sqrt
106function on a
107.Tn VAX
108is accurate to within 0.501
109.Em ulps .
110Sqrt on a machine that conforms to
111.Tn IEEE
112754 is correctly rounded
113in accordance with the rounding mode in force; the error is less than
114half an
115.Em ulp
116in the default mode (round\-to\-nearest).
117An
118.Em ulp
119is one
120.Em U Ns nit
121in the
122.Em L Ns ast
123.Em P Ns lace
124carried.
125.Sh SEE ALSO
126.Xr math 3
127.Sh STANDARDS
128The
129.Fn sqrt
130function conforms to
131.St -isoC .
132.Sh HISTORY
133The
134.Fn cbrt
135function appeared in
136.Bx 4.3 .