1.\" $NetBSD: nextafter.3,v 1.5 2015/09/13 10:58:30 he Exp $ 2.\" 3.\" Copyright (c) 2011 Jukka Ruohonen <jruohonen@iki.fi> 4.\" All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 15.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 16.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 17.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 18.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 19.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 20.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 21.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 22.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 23.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 24.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 25.\" POSSIBILITY OF SUCH DAMAGE. 26.\" 27.Dd September 13, 2015 28.Dt NEXTAFTER 3 29.Os 30.Sh NAME 31.Nm nextafter , 32.Nm nextafterf , 33.Nm nextafterl , 34.Nm nexttoward , 35.Nm nexttowardf 36.\" 37.\" XXX: Not yet implemented. 38.\" 39.\" .Nm nexttowardl 40.\" 41.Nd next representable floating-point number 42.Sh LIBRARY 43.Lb libm 44.Sh SYNOPSIS 45.In math.h 46.Ft double 47.Fn nextafter "double x" "double y" 48.Ft float 49.Fn nextafterf "float x" "float y" 50.Ft long double 51.Fn nextafterl "long double x" "long double y" 52.Ft double 53.Fn nexttoward "double x" "long double y" 54.Ft float 55.Fn nexttowardf "float x" "long double y" 56.Sh DESCRIPTION 57The 58.Fn nextafter , 59.Fn nextafterf , 60and 61.Fn nextafterl 62functions return the next machine representable number from 63.Fa x 64in direction of 65.Fa y . 66In other words, if 67.Fa y 68is less than 69.Fa x , 70the functions return the largest representable floating-point number less than 71.Fa x . 72When 73.Fa x 74equals 75.Fa y , 76the value of 77.Fa y 78is returned. 79The three functions differ only in the type of the return value and 80.Fa x . 81.Pp 82The 83.Fn nexttoward 84and 85.Fn nexttowardf 86functions are equivalent to the 87.Fn nextafter 88family of functions with two exceptions: 89.Bl -enum -offset indent 90.It 91The second parameter has a type 92.Vt long double . 93.It 94The return value is 95.Fa y 96converted to the type of the function, provided that 97.Fa x 98equals 99.Fa y . 100.El 101.Sh RETURN VALUES 102Upon successful completion, the described functions return 103the next representable floating-point value as described above. 104If 105.Fa x 106is finite but an overflow would occur, 107a range error follows and the functions return 108.Dv \*(Pm\*HHUGE_VAL , 109.Dv \*(Pm\*HHUGE_VALF , 110or 111.Dv \*(Pm\*HHUGE_VALL 112with the same sign as 113.Fa x . 114When either 115.Fa x 116or 117.Fa y 118is \*(Na, a \*(Na is returned. 119When 120.Fa x 121is not 122.Fa y 123but the function value is subnormal, zero, or underflows, 124a range error occurs, and either 0.0 or the correct function 125value (if representable) is returned. 126.Sh SEE ALSO 127.Xr math 3 128.Sh STANDARDS 129The described functions conform to 130.St -isoC-99 . 131