1.\" Copyright (c) 1985, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" %sccs.include.redist.man% 5.\" 6.\" @(#)rint.3 8.2 (Berkeley) 12/11/93 7.\" 8.Dd 9.Dt RINT 3 10.Os 11.Sh NAME 12.Nm rint 13.Nd round-to-closest integer functions 14.Sh SYNOPSIS 15.Fd #include <math.h> 16.Ft double 17.Fn rint "double x" 18.Sh DESCRIPTION 19The 20.Fn rint 21function finds the integer (represented as a double precision number) 22nearest to 23.Fa x 24in the direction of the prevailing rounding mode. 25.Sh NOTES 26On a 27.Tn VAX , 28.Fn rint x 29is equivalent to adding half to the magnitude 30and then rounding towards zero. 31.Pp 32In the default rounding mode, to nearest, 33on a machine that conforms to 34.Tn IEEE 35754, 36.Fn rint x 37is the integer nearest 38.Fa x 39with the additional stipulation 40that if 41.Li |rint(x)\-x|=1/2 42then 43.Fn rint x 44is even. 45Other rounding modes can make 46.Fn rint 47act like 48.Fn floor , 49or like 50.Fn ceil , 51or round towards zero. 52.Pp 53Another way to obtain an integer near 54.Fa x 55is to declare (in C) 56.Bd -literal -offset indent 57double x;\0\0\0\0 int k;\0\0\0\0k\0=\0x; 58.Ed 59.Pp 60Most C compilers round 61.Fa x 62towards 0 to get the integer 63.Fa k , 64but 65some do otherwise. 66If in doubt, use 67.Fn floor , 68.Fn ceil , 69or 70.Fn rint 71first, whichever you intend. 72Also note that, if x is larger than 73.Fa k 74can accommodate, the value of 75.Fa k 76and the presence or absence of an integer overflow are hard to 77predict. 78.Sh SEE ALSO 79.Xr abs 3 , 80.Xr fabs 3 , 81.Xr ceil 3 , 82.Xr floor 3 , 83.Xr ieee 3 , 84.Xr math 3 85.Sh HISTORY 86A 87.Fn rint 88function appeared in 89.At v6 . 90