1.\" $OpenBSD: logb.3,v 1.4 2008/12/12 00:10:26 martynas 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: December 12 2008 $ 32.Dt IEEE_TEST 3 33.Os 34.Sh NAME 35.Nm logb , 36.Nm logbf , 37.Nm logbl , 38.Nm scalb , 39.Nm scalbf , 40.Nm significand , 41.Nm significandf 42.Nd IEEE test functions 43.Sh SYNOPSIS 44.Fd #include <math.h> 45.Ft double 46.Fn logb "double x" 47.Ft float 48.Fn logbf "float x" 49.Ft long double 50.Fn logbl "long double x" 51.Ft double 52.Fn scalb "double x" "double n" 53.Ft float 54.Fn scalbf "float x" "float n" 55.Ft double 56.Fn significand "double x" 57.Ft float 58.Fn significandf "float x" 59.Sh DESCRIPTION 60These functions allow users to test conformance to 61.St -ieee754 . 62Their use is not otherwise recommended. 63.Pp 64.Fn logb x 65returns 66.Fa x Ns 's exponent 67.Fa n , 68a signed integer converted to double\-precision floating\-point. 69.Fn logb \*(Pm\*(If 70= +\*(If; 71.Fn logb 0 72= -\*(If with a division by zero exception. 73.Fn logbf 74is the single precision form of 75.Fn logb . 76.Fn logbl 77is the extended precision form of 78.Fn logb . 79.Pp 80.Fn scalb x n 81returns 82.Fa x Ns \(**(2** Ns Fa n ) 83computed by exponent manipulation. 84.Fn scalbf 85is the single precision form of 86.Fn scalb . 87.Pp 88.Fn significand x 89returns 90.Fa sig , 91where 92.Fa x 93:= 94.Fa sig No \(** 2** Ns Fa n 95with 1 \(<= 96.Fa sig 97< 2. 98.Fn significand x 99is not defined when 100.Fa x 101is 0, \*(Pm\*(If, or \*(Na. 102.Fn significandf 103is the single precision for of 104.Fn significand . 105.Sh SEE ALSO 106.Xr ieee 3 , 107.Xr math 3 108.Sh STANDARDS 109.St -ieee754 110