1.\" $NetBSD: nextafter.3,v 1.4 2011/09/18 05:33:14 jruoho 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 18, 2011 28.Dt NEXTAFTER 3 29.Os 30.Sh NAME 31.Nm nextafter , 32.Nm nextafterf , 33.Nm nextafterl , 34.Nm nexttoward 35.\" 36.\" XXX: Not yet implemented. 37.\" 38.\" .Nm nexttowardf , 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.Sh DESCRIPTION 55The 56.Fn nextafter , 57.Fn nextafterf , 58and 59.Fn nextafterl 60functions return the next machine representable number from 61.Fa x 62in direction of 63.Fa y . 64In other words, if 65.Fa y 66is less than 67.Fa x , 68the functions return the largest representable floating-point number less than 69.Fa x . 70When 71.Fa x 72equals 73.Fa y , 74the value of 75.Fa y 76is returned. 77The three functions differ only in the type of the return value and 78.Fa x . 79.Pp 80The 81.Fn nexttoward 82function is equivalent to the 83.Fn nextafter 84family of functions with two exceptions: 85.Bl -enum -offset indent 86.It 87The second parameter has a type 88.Vt long double . 89.It 90The return value is 91.Fa y 92converted to the type of the function, provided that 93.Fa x 94equals 95.Fa y . 96.El 97.Sh RETURN VALUES 98Upon successful completion, the described functions return 99the next representable floating-point value as described above. 100If 101.Fa x 102is finite but an overflow would occur, 103a range error follows and the functions return 104.Dv \*(Pm\*HHUGE_VAL , 105.Dv \*(Pm\*HHUGE_VALF , 106or 107.Dv \*(Pm\*HHUGE_VALL 108with the same sign as 109.Fa x . 110When either 111.Fa x 112or 113.Fa y 114is \*(Na, a \*(Na is returned. 115When 116.Fa x 117is not 118.Fa y 119but the function value is subnormal, zero, or underflows, 120a range error occurs, and either 0.0 or the correct function 121value (if representable) is returned. 122.Sh SEE ALSO 123.Xr math 3 124.Sh STANDARDS 125The described functions conform to 126.St -isoC-99 . 127