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136 lines
3.3 KiB
Groff
136 lines
3.3 KiB
Groff
.\" Copyright (c) 1985, 1991 Regents of the University of California.
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" from: @(#)sqrt.3 6.4 (Berkeley) 5/6/91
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.\" $Id: sqrt.3,v 1.1.1.1 1994/08/19 09:39:42 jkh Exp $
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.\"
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.Dd May 6, 1991
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.Dt SQRT 3
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.Os
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.Sh NAME
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.Nm cbrt ,
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.Nm cbrtf ,
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.Nm sqrt ,
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.Nm sqrtf
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.Nd cube root and square root functions
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.Sh SYNOPSIS
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.Fd #include <math.h>
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.Ft double
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.Fn cbrt "double x"
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.Ft float
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.Fn cbrtf "float x"
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.Ft double
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.Fn sqrt "double x"
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.Ft float
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.Fn sqrtf "float x"
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.Sh DESCRIPTION
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The
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.Fn cbrt
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and the
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.Fn cbrtf
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functions compute
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the cube root of
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.Ar x .
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.Pp
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The
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.Fn sqrt
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and the
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.Fn sqrtf
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functions compute the
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non-negative square root of x.
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.Sh RETURN VALUES
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The
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.Fn cbrt
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and the
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.Fn cbrtf
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functions return the requested cube root.
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The
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.Fn sqrt
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and the
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.Fn sqrtf
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functions return the requested square root
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unless an error occurs.
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On the
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.Tn VAX
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or
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.Tn Tahoe
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processor an attempt to take the
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.Fn sqrt
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of negative
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.Fa x
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causes an error; in this event,
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the global variable
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.Va errno
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is set to
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.Dv EDOM
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and a reserved operand fault is generated.
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.Sh ERROR (due to Roundoff etc.)
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The
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.Fn cbrt
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function
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is accurate to within 0.7
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.Em ulps .
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.Pp
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The
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.Fn sqrt
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function on a
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.Tn VAX
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is accurate to within 0.501
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.Em ulps .
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Sqrt on a machine that conforms to
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.Tn IEEE
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754 is correctly rounded
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in accordance with the rounding mode in force; the error is less than
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half an
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.Em ulp
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in the default mode (round\-to\-nearest).
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An
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.Em ulp
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is one
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.Em U Ns nit
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in the
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.Em L Ns ast
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.Em P Ns lace
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carried.
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.Sh SEE ALSO
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.Xr math 3 ,
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.Xr infnan 3
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.Sh STANDARDS
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The
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.Nm sqrt
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function conforms to
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.St -ansiC .
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.Sh HISTORY
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The
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.Nm cbrt
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function appeared in
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.Bx 4.3 .
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