131 lines
3.2 KiB
Groff
131 lines
3.2 KiB
Groff
.\" Copyright (c) 2003 Mike Barcroft <mike@FreeBSD.org>
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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 AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd February 12, 2003
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.Dt FPCLASSIFY 3
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.Os
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.Sh NAME
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.Nm fpclassify , isfinite , isinf , isnan , isnormal
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.Nd "classify a floating-point number"
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In math.h
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.Ft int
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.Fn fpclassify "real-floating x"
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.Ft int
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.Fn isfinite "real-floating x"
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.Ft int
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.Fn isinf "real-floating x"
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.Ft int
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.Fn isnan "real-floating x"
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.Ft int
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.Fn isnormal "real-floating x"
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.Sh DESCRIPTION
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The
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.Fn fpclassify
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macro takes an argument of
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.Fa x
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and returns one of the following manifest constants.
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.Bl -tag -width ".Dv FP_SUBNORMAL"
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.It Dv FP_INFINITE
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Indicates that
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.Fa x
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is an infinite number.
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.It Dv FP_NAN
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Indicates that
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.Fa x
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is not a number (NaN).
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.It Dv FP_NORMAL
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Indicates that
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.Fa x
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is a normalized number.
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.It Dv FP_SUBNORMAL
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Indicates that
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.Fa x
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is a denormalized number.
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.It Dv FP_ZERO
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Indicates that
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.Fa x
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is zero (0 or \-0).
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.El
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.Pp
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The
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.Fn isfinite
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macro returns a non-zero value if and only if its argument has
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a finite (zero, subnormal, or normal) value.
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The
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.Fn isinf ,
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.Fn isnan ,
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and
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.Fn isnormal
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macros return non-zero if and only if
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.Fa x
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is an infinity, NaN,
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or a non-zero normalized number, respectively.
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.Pp
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The symbol
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.Fn isnanf
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is provided as an alias to
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.Fn isnan
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for compatibility, and its use is deprecated.
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.Sh SEE ALSO
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.Xr isgreater 3 ,
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.Xr math 3 ,
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.Xr signbit 3
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.Sh STANDARDS
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The
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.Fn fpclassify ,
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.Fn isfinite ,
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.Fn isinf ,
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.Fn isnan ,
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and
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.Fn isnormal
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macros conform to
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.St -isoC-99 .
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.Sh HISTORY
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The
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.Fn fpclassify ,
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.Fn isfinite ,
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.Fn isinf ,
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.Fn isnan ,
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and
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.Fn isnormal
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macros were added in
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.Fx 5.1 .
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.Bx 3
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introduced
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.Fn isinf
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and
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.Fn isnan
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functions, which accepted
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.Vt double
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arguments; these have been superseded by the macros
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described above.
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.Sh BUGS
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By default, the DEC Alpha architecture does not support IEEE rounding.
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See the compiler documentation for additional details.
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