127 lines
3.3 KiB
Groff
127 lines
3.3 KiB
Groff
.\" $NetBSD: nextafter.3,v 1.4 2011/09/18 05:33:14 jruoho Exp $
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.\"
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.\" Copyright (c) 2011 Jukka Ruohonen <jruohonen@iki.fi>
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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.Dd September 18, 2011
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.Dt NEXTAFTER 3
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.Os
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.Sh NAME
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.Nm nextafter ,
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.Nm nextafterf ,
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.Nm nextafterl ,
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.Nm nexttoward
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.\"
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.\" XXX: Not yet implemented.
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.\"
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.\" .Nm nexttowardf ,
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.\" .Nm nexttowardl
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.\"
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.Nd next representable floating-point number
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.Sh LIBRARY
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.Lb libm
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.Sh SYNOPSIS
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.In math.h
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.Ft double
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.Fn nextafter "double x" "double y"
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.Ft float
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.Fn nextafterf "float x" "float y"
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.Ft long double
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.Fn nextafterl "long double x" "long double y"
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.Ft double
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.Fn nexttoward "double x" "long double y"
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.Sh DESCRIPTION
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The
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.Fn nextafter ,
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.Fn nextafterf ,
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and
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.Fn nextafterl
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functions return the next machine representable number from
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.Fa x
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in direction of
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.Fa y .
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In other words, if
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.Fa y
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is less than
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.Fa x ,
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the functions return the largest representable floating-point number less than
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.Fa x .
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When
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.Fa x
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equals
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.Fa y ,
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the value of
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.Fa y
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is returned.
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The three functions differ only in the type of the return value and
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.Fa x .
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.Pp
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The
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.Fn nexttoward
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function is equivalent to the
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.Fn nextafter
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family of functions with two exceptions:
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.Bl -enum -offset indent
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.It
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The second parameter has a type
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.Vt long double .
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.It
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The return value is
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.Fa y
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converted to the type of the function, provided that
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.Fa x
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equals
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.Fa y .
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.El
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.Sh RETURN VALUES
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Upon successful completion, the described functions return
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the next representable floating-point value as described above.
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If
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.Fa x
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is finite but an overflow would occur,
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a range error follows and the functions return
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.Dv \*(Pm\*HHUGE_VAL ,
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.Dv \*(Pm\*HHUGE_VALF ,
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or
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.Dv \*(Pm\*HHUGE_VALL
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with the same sign as
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.Fa x .
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When either
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.Fa x
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or
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.Fa y
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is \*(Na, a \*(Na is returned.
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When
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.Fa x
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is not
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.Fa y
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but the function value is subnormal, zero, or underflows,
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a range error occurs, and either 0.0 or the correct function
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value (if representable) is returned.
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.Sh SEE ALSO
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.Xr math 3
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.Sh STANDARDS
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The described functions conform to
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.St -isoC-99 .
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