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 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" @(#)rint.3 5.1 (Berkeley) 5/2/91 33.\" 34.Dd May 2, 1991 35.Dt RINT 3 36.Os 37.Sh NAME 38.Nm rint 39.Nd and round-to-closest integer functions 40.Sh SYNOPSIS 41.Fd #include <math.h> 42.Ft double 43.Fn rint "double x" 44.Sh DESCRIPTION 45The 46.Fn rint 47function finds the integer (represented as a double precision number) 48nearest to 49.Fa x 50in the direction of the prevailing rounding mode. 51.Sh NOTES 52On a 53.Tn VAX , 54.Fn rint x 55is equivalent to adding half to the magnitude 56and then rounding towards zero. 57.Pp 58In the default rounding mode, to nearest, 59on a machine that conforms to 60.Tn IEEE 61754, 62.Fn rint x 63is the integer nearest 64.Fa x 65with the additional stipulation 66that if 67.Li |rint(x)\-x|=1/2 68then 69.Fn rint x 70is even. 71Other rounding modes can make 72.Fn rint 73act like 74.Fn floor , 75or like 76.Fn ceil , 77or round towards zero. 78.Pp 79Another way to obtain an integer near 80.Fa x 81is to declare (in C) 82.Bd -literal -offset indent 83double x;\0\0\0\0 int k;\0\0\0\0k\0=\0x; 84.Ed 85.Pp 86Most C compilers round 87.Fa x 88towards 0 to get the integer 89.Fa k , 90but 91some do otherwise. 92If in doubt, use 93.Fn floor , 94.Fn ceil , 95or 96.Fn rint 97first, whichever you intend. 98Also note that, if x is larger than 99.Fa k 100can accommodate, the value of 101.Fa k 102and the presence or absence of an integer overflow are hard to 103predict. 104.Sh SEE ALSO 105.Xr abs 3 , 106.Xr fabs 3 , 107.Xr ceil 3 , 108.Xr floor 3 , 109.Xr ieee 3 , 110.Xr math 3 111.Sh HISTORY 112A 113.Fn rint 114function appeared in 115.At v6 . 116