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.\" from: @(#)ieee.3 6.4 (Berkeley) 5/6/91 33.\" $Id: ieee.3,v 1.7 1994/03/10 18:15:07 jtc Exp $ 34.\" 35.Dd Feb 25, 1994 36.Dt IEEE 3 37.Os 38.Sh NAME 39.Nm copysign , 40.Nm finite , 41.Nm ilogb , 42.Nm nextafter , 43.Nm remainder , 44.Nm scalbn 45.Nd Functions for IEEE arithmetic 46.Sh SYNOPSIS 47.Fd #include <math.h> 48.Ft double 49.Fn copysign "double x" "double y" 50.Ft int 51.Fn finite "double x" 52.Ft int 53.Fn ilogb "double x" 54.Ft double 55.Fn nextafter "double x" "double y" 56.Ft double 57.Fn remainder "double x" "double y" 58.Ft double 59.Fn scalbn "double x" "int n" 60.Sh DESCRIPTION 61These functions are required or recommended by 62.St -ieee754 . 63.Pp 64.Fn copysign 65returns 66.Fa x 67with its sign changed to 68.Fa y Ns 's. 69.Pp 70.Fn finite 71returns the value 1 just when 72\-\*(If \*(Lt 73.Fa x 74\*(Lt +\*(If; 75otherwise a 76zero is returned 77(when 78.Pf \\*(Ba Ns Fa x Ns \\*(Ba 79= \*(If or 80.Fa x 81is \*(Na 82.Pp 83.Fn ilogb 84returns 85.Fa x Ns 's exponent 86.Fa n , 87in integer format. 88.Fn ilogb \*(Pm\*(If 89returns 90.Dv INT_MAX 91and 92.Fn ilogb 0 93returns 94.Dv INT_MIN . 95.Pp 96.Fn nextafter 97returns the next machine representable number from 98.Fa x 99in direction 100.Fa y . 101.Pp 102.Fn remainder 103returns the remainder 104.Fa r 105:= 106.Fa x 107\- 108.Fa n\(**y 109where 110.Fa n 111is the integer nearest the exact value of 112.Bk -words 113.Fa x Ns / Ns Fa y ; 114.Ek 115moreover if 116.Pf \\*(Ba Fa n 117\- 118.Sm off 119.Fa x No / Fa y No \\*(Ba 120.Sm on 121= 1221/2 123then 124.Fa n 125is even. Consequently 126the remainder is computed exactly and 127.Sm off 128.Pf \\*(Ba Fa r No \\*(Ba 129.Sm on 130\*(Le 131.Sm off 132.Pf \\*(Ba Fa y No \\*(Ba/2. 133.Sm on 134But 135.Fn remainder x 0 136and 137.Fn remainder \*(If 0 138are invalid operations that produce a \*(Na. 139.Pp 140.Fn scalbn 141returns 142.Fa x Ns \(**(2** Ns Fa n ) 143computed by exponent manipulation. 144.Sh SEE ALSO 145.Xr math 3 146.Sh HISTORY 147The 148.Nm ieee 149functions appeared in 150.Bx 4.3 . 151.Sh STANDARDS 152.St -ieee754 153