xref: /minix3/lib/libm/man/nextafter.3 (revision 0a6a1f1d05b60e214de2f05a7310ddd1f0e590e7)

.\" $NetBSD: nextafter.3,v 1.5 2015/09/13 10:58:30 he Exp $
.\"
.\" Copyright (c) 2011 Jukka Ruohonen <jruohonen@iki.fi>
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
.\" PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
.Dd September 13, 2015
.Dt NEXTAFTER 3
.Os
.Sh NAME
.Nm nextafter ,
.Nm nextafterf ,
.Nm nextafterl ,
.Nm nexttoward ,
.Nm nexttowardf
.\"
.\" XXX: Not yet implemented.
.\"
.\" .Nm nexttowardl
.\"
.Nd next representable floating-point number
.Sh LIBRARY
.Lb libm
.Sh SYNOPSIS
.In math.h
.Ft double
.Fn nextafter "double x" "double y"
.Ft float
.Fn nextafterf "float x" "float y"
.Ft long double
.Fn nextafterl "long double x" "long double y"
.Ft double
.Fn nexttoward "double x" "long double y"
.Ft float
.Fn nexttowardf "float x" "long double y"
.Sh DESCRIPTION
The
.Fn nextafter ,
.Fn nextafterf ,
and
.Fn nextafterl
functions return the next machine representable number from
.Fa x
in direction of
.Fa y .
In other words, if
.Fa y
is less than
.Fa x ,
the functions return the largest representable floating-point number less than
.Fa x .
When
.Fa x
equals
.Fa y ,
the value of
.Fa y
is returned.
The three functions differ only in the type of the return value and
.Fa x .
.Pp
The
.Fn nexttoward
and
.Fn nexttowardf
functions are equivalent to the
.Fn nextafter
family of functions with two exceptions:
.Bl -enum -offset indent
.It
The second parameter has a type
.Vt long double .
.It
The return value is
.Fa y
converted to the type of the function, provided that
.Fa x
equals
.Fa y .
.El
.Sh RETURN VALUES
Upon successful completion, the described functions return
the next representable floating-point value as described above.
If
.Fa x
is finite but an overflow would occur,
a range error follows and the functions return
.Dv \*(Pm\*HHUGE_VAL ,
.Dv  \*(Pm\*HHUGE_VALF ,
or
.Dv  \*(Pm\*HHUGE_VALL
with the same sign as
.Fa x .
When either
.Fa x
or
.Fa y
is \*(Na, a \*(Na is returned.
When
.Fa x
is not
.Fa y
but the function value is subnormal, zero, or underflows,
a range error occurs, and either 0.0 or the correct function
value (if representable) is returned.
.Sh SEE ALSO
.Xr math 3
.Sh STANDARDS
The described functions conform to
.St -isoC-99 .