1.\" $OpenBSD: ilogb.3,v 1.8 2020/10/31 15:14:39 kettenis Exp $ 2.\" Copyright (c) 1985, 1991 Regents of the University of California. 3.\" All rights reserved. 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice, this list of conditions and the following disclaimer. 10.\" 2. Redistributions in binary form must reproduce the above copyright 11.\" notice, this list of conditions and the following disclaimer in the 12.\" documentation and/or other materials provided with the distribution. 13.\" 3. Neither the name of the University nor the names of its contributors 14.\" may be used to endorse or promote products derived from this software 15.\" without specific prior written permission. 16.\" 17.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 18.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 21.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27.\" SUCH DAMAGE. 28.\" 29.\" from: @(#)ieee.3 6.4 (Berkeley) 5/6/91 30.\" 31.Dd $Mdocdate: October 31 2020 $ 32.Dt ILOGB 3 33.Os 34.Sh NAME 35.Nm ilogb , 36.Nm ilogbf , 37.Nm ilogbl 38.Nd extract exponent 39.Sh SYNOPSIS 40.In math.h 41.Ft int 42.Fn ilogb "double x" 43.Ft int 44.Fn ilogbf "float x" 45.Ft int 46.Fn ilogbl "long double x" 47.Sh DESCRIPTION 48.Fn ilogb 49returns 50.Fa x Ns 's exponent 51.Fa n , 52in integer format. 53.Fn ilogb \(+-infinity 54returns 55.Dv INT_MAX , 56.Fn ilogb NaN 57returns 58.Dv FP_ILOGBNAN 59and 60.Fn ilogb 0 61returns 62.Dv FP_ILOGB0 . 63The 64.Fn ilogbf 65function is a single precision version of 66.Fn ilogb . 67The 68.Fn ilogbl 69function is an extended precision version of 70.Fn ilogb . 71.Sh SEE ALSO 72.Xr ffs 3 , 73.Xr frexp 3 74.Sh STANDARDS 75.St -ieee754 76.Sh HISTORY 77The 78.Nm ilogb , 79.Nm ilogbf 80and 81.Nm ilogbl 82functions appeared in 83.Bx 4.3 , 84.Nx 1.1 85and 86.Ox 4.5 , 87respectively. 88