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1.\" Copyright (c) 2003 Mike Barcroft <mike@FreeBSD.org>
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25.\" $FreeBSD: src/lib/libc/gen/fpclassify.3,v 1.5 2004/07/09 06:37:44 das Exp $
26.\"
27.Dd December 11, 2006
28.Dt FPCLASSIFY 3
29.Os
30.Sh NAME
31.Nm fpclassify , isfinite , isinf , isnan , isnormal
32.Nd "classify a floating-point number"
33.Sh LIBRARY
34.Lb libm
35.Sh SYNOPSIS
36.In math.h
37.Ft int
38.Fn fpclassify "real-floating x"
39.Ft int
40.Fn isfinite "real-floating x"
41.Ft int
42.Fn isinf "real-floating x"
43.Ft int
44.Fn isnan "real-floating x"
45.Ft int
46.Fn isnormal "real-floating x"
47.Sh DESCRIPTION
48The
49.Fn fpclassify
50macro takes an argument of
51.Fa x
52and returns one of the following manifest constants.
53.Bl -tag -width ".Dv FP_SUBNORMAL"
54.It Dv FP_INFINITE
55Indicates that
56.Fa x
57is an infinite number.
58.It Dv FP_NAN
59Indicates that
60.Fa x
61is not a number (NaN).
62.It Dv FP_NORMAL
63Indicates that
64.Fa x
65is a normalized number.
66.It Dv FP_SUBNORMAL
67Indicates that
68.Fa x
69is a denormalized number.
70.It Dv FP_ZERO
71Indicates that
72.Fa x
73is zero (0 or \-0).
74.El
75.Pp
76The
77.Fn isfinite
78macro returns a non-zero value if and only if its argument has
79a finite (zero, subnormal, or normal) value.
80The
81.Fn isinf ,
82.Fn isnan ,
83and
84.Fn isnormal
85macros return non-zero if and only if
86.Fa x
87is an infinity, NaN,
88or a non-zero normalized number, respectively.
89.Sh SEE ALSO
90.Xr isgreater 3 ,
91.Xr math 3 ,
92.Xr signbit 3
93.Sh STANDARDS
94The
95.Fn fpclassify ,
96.Fn isfinite ,
97.Fn isinf ,
98.Fn isnan ,
99and
100.Fn isnormal
101macros conform to
102.St -isoC-99 .
103.Sh HISTORY
104.Bx 3
105introduced
106.Fn isinf
107and
108.Fn isnan
109functions, which accepted
110.Vt double
111arguments; these have been superseded by the macros
112described above.