1.\" $NetBSD: ldexp.3,v 1.4 2011/09/18 05:33:13 jruoho 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 September 18, 2011 37.Dt LDEXP 3 38.Os 39.Sh NAME 40.Nm ldexp , 41.Nm ldexpf 42.Nd multiply floating-point number by integral power of 2 43.Sh LIBRARY 44.Lb libm 45.Sh SYNOPSIS 46.In math.h 47.Ft double 48.Fn ldexp "double x" "int exp" 49.Ft float 50.Fn ldexpf "float x" "int exp" 51.Sh DESCRIPTION 52The 53.Fn ldexp 54family of functions compute 55.Bd -ragged -offset indent 56.Va x 57* 582^\fIexp\fR 59.Ed 60.Pp 61for a real floating-point number 62.Fa x . 63.Sh RETURN VALUES 64The functions return the value of 65.Fa x 66times 2 raised to the power 67.Fa exp . 68Otherwise the following may occur: 69.Bl -enum -offset indent 70.It 71If 72.Fa x 73is \*(Na, a \*(Na is returned. 74.It 75If 76.Fa exp 77is zero or 78.Fa x 79is either \*(Pm 0 or \*(Pm\[if], 80.Fa x 81is returned. 82.It 83If the call would cause an overflow, a range error occurs and either 84.Dv \*(Pm\*HHUGE_VAL , 85.Dv \*(Pm\*HHUGE_VALF , 86or 87.Dv \*(Pm\*HHUGE_VALL 88is returned, depending on the sign of 89.Fa x 90and the type of the return value. 91.It 92If an underflow would be caused by the correct value, 93and the value is not representable, either 0.0 or 94an implementation-defined value is returned. 95.El 96.Sh SEE ALSO 97.Xr frexp 3 , 98.Xr math 3 , 99.Xr modf 3 100.Sh STANDARDS 101The described functions conform to 102.St -isoC-99 . 103