1.\" $OpenBSD: logb.3,v 1.9 2013/06/05 03:40:26 tedu 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: June 5 2013 $ 32.Dt LOGB 3 33.Os 34.Sh NAME 35.Nm logb , 36.Nm logbf , 37.Nm logbl , 38.Nm scalb , 39.Nm scalbf , 40.\".Nm scalbl , 41.Nm significand , 42.Nm significandf 43.Nd IEEE test functions 44.Sh SYNOPSIS 45.In math.h 46.Ft double 47.Fn logb "double x" 48.Ft float 49.Fn logbf "float x" 50.Ft long double 51.Fn logbl "long double x" 52.Ft double 53.Fn scalb "double x" "double n" 54.Ft float 55.Fn scalbf "float x" "float n" 56.\".Ft long double 57.\".Fn scalbl "long double x" "long double n" 58.Ft double 59.Fn significand "double x" 60.Ft float 61.Fn significandf "float x" 62.Sh DESCRIPTION 63These functions allow users to test conformance to 64.St -ieee754 . 65Their use is not otherwise recommended. 66.Pp 67.Fn logb x 68returns 69.Fa x Ns 's exponent 70.Fa n , 71a signed integer converted to double\-precision floating\-point. 72.Fn logb \*(Pm\*(If 73= +\*(If; 74.Fn logb 0 75= -\*(If with a division by zero exception. 76.Fn logbf 77is the single precision form of 78.Fn logb . 79.Fn logbl 80is the extended precision form of 81.Fn logb . 82.Pp 83.Fn scalb x n 84returns 85.Fa x Ns \(**(2** Ns Fa n ) 86computed by exponent manipulation. 87.Fn scalbf 88is the single precision form of 89.Fn scalb . 90.\".Fn scalbl 91.\"is the extended precision form of 92.\".Fn scalb . 93.Pp 94.Fn significand x 95returns 96.Fa sig , 97where 98.Fa x 99:= 100.Fa sig No \(** 2** Ns Fa n 101with 1 \(<= 102.Fa sig 103< 2. 104.Fn significand x 105is not defined when 106.Fa x 107is 0, \*(Pm\*(If, or \*(Na. 108.Fn significandf 109is the single precision for of 110.Fn significand . 111.Sh SEE ALSO 112.Xr ilogb 3 , 113.Xr scalbn 3 114.Sh STANDARDS 115.St -ieee754 116