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+.\" Copyright (c) 1985, 1991, 1993
+.\"	The Regents of the University of California.  All rights reserved.
+.\"
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\"    notice, this list of conditions and the following disclaimer.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\"    notice, this list of conditions and the following disclaimer in the
+.\"    documentation and/or other materials provided with the distribution.
+.\" 3. All advertising materials mentioning features or use of this software
+.\"    must display the following acknowledgement:
+.\"	This product includes software developed by the University of
+.\"	California, Berkeley and its contributors.
+.\" 4. Neither the name of the University nor the names of its contributors
+.\"    may be used to endorse or promote products derived from this software
+.\"    without specific prior written permission.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+.\" SUCH DAMAGE.
+.\"
+.\"     @(#)rint.3	8.2 (Berkeley) 12/11/93
+.\"
+.Dd December 11, 1993
+.Dt RINT 3
+.Os
+.Sh NAME
+.Nm rint
+.Nd round-to-closest integer functions
+.Sh SYNOPSIS
+.Fd #include <math.h>
+.Ft double
+.Fn rint "double x"
+.Sh DESCRIPTION
+The
+.Fn rint
+function finds the integer (represented as a double precision number)
+nearest to
+.Fa x
+in the direction of the prevailing rounding mode.
+.Sh NOTES
+On a
+.Tn VAX ,
+.Fn rint x
+is equivalent to adding half to the magnitude
+and then rounding towards zero.
+.Pp
+In the default rounding mode, to nearest,
+on a machine that conforms to
+.Tn IEEE
+754,
+.Fn rint x
+is the integer nearest
+.Fa x
+with the additional stipulation
+that if
+.Li |rint(x)\-x|=1/2
+then
+.Fn rint x
+is even.
+Other rounding modes can make
+.Fn rint
+act like
+.Fn floor ,
+or like
+.Fn ceil ,
+or round towards zero.
+.Pp
+Another way to obtain an integer near
+.Fa x
+is to declare (in C)
+.Bd -literal -offset indent
+double x;\0\0\0\0 int k;\0\0\0\0k\0=\0x;
+.Ed
+.Pp
+Most C compilers round
+.Fa x
+towards 0 to get the integer
+.Fa k ,
+but
+some do otherwise.
+If in doubt, use
+.Fn floor ,
+.Fn ceil ,
+or
+.Fn rint
+first, whichever you intend.
+Also note that, if x is larger than
+.Fa k
+can accommodate, the value of
+.Fa k
+and the presence or absence of an integer overflow are hard to
+predict.
+.Sh SEE ALSO
+.Xr abs 3 ,
+.Xr fabs 3 ,
+.Xr ceil 3 ,
+.Xr floor 3 ,
+.Xr ieee 3 ,
+.Xr math 3
+.Sh HISTORY
+A
+.Fn rint
+function appeared in
+.At v6 .