1.\" $NetBSD: ldexp.3,v 1.1 2006/07/03 16:03:56 drochner Exp $ 2.\" 3.\" Copyright (c) 1991, 1993 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" This code is derived from software contributed to Berkeley by 7.\" the American National Standards Committee X3, on Information 8.\" Processing Systems. 9.\" 10.\" Redistribution and use in source and binary forms, with or without 11.\" modification, are permitted provided that the following conditions 12.\" are met: 13.\" 1. Redistributions of source code must retain the above copyright 14.\" notice, this list of conditions and the following disclaimer. 15.\" 2. Redistributions in binary form must reproduce the above copyright 16.\" notice, this list of conditions and the following disclaimer in the 17.\" documentation and/or other materials provided with the distribution. 18.\" 3. Neither the name of the University nor the names of its contributors 19.\" may be used to endorse or promote products derived from this software 20.\" without specific prior written permission. 21.\" 22.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32.\" SUCH DAMAGE. 33.\" 34.\" @(#)ldexp.3 8.2 (Berkeley) 4/19/94 35.\" 36.Dd March 21, 2006 37.Dt LDEXP 3 38.Os 39.Sh NAME 40.Nm ldexp 41.Nd multiply floating-point number by integral power of 2 42.Sh LIBRARY 43.Lb libm 44.Sh SYNOPSIS 45.In math.h 46.Ft double 47.Fn ldexp "double x" "int exp" 48.Ft float 49.Fn ldexpf "float x" "int exp" 50.Sh DESCRIPTION 51The 52.Fn ldexp 53function multiplies a floating-point number by an integral 54power of 2. 55.Sh RETURN VALUES 56The 57.Fn ldexp 58function returns the value of 59.Fa x 60times 2 raised to the power 61.Fa exp . 62.Pp 63If the input 64.Va x 65is a NaN, infinity, or 0.0, it is returned unchanged. 66.Pp 67If the result would cause an overflow, 68the global variable 69.Va errno 70is set to 71.Er ERANGE 72and infinity is returned, with the same sign as 73.Fa x . 74.Pp 75If the result would cause underflow to 0.0, 76the global variable 77.Va errno 78is set to 79.Er ERANGE 80and the value 0.0 is returned. 81.Sh SEE ALSO 82.Xr frexp 3 , 83.Xr math 3 , 84.Xr modf 3 85.Sh STANDARDS 86The 87.Fn ldexp 88function conforms to 89.St -ansiC . 90