1finite(3)                  Library Functions Manual                  finite(3)
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3
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NAME

6       finite,  finitef, finitel, isinf, isinff, isinfl, isnan, isnanf, isnanl
7       - BSD floating-point classification functions
8

LIBRARY

10       Math library (libm, -lm)
11

SYNOPSIS

13       #include <math.h>
14
15       int finite(double x);
16       int finitef(float x);
17       int finitel(long double x);
18
19       int isinf(double x);
20       int isinff(float x);
21       int isinfl(long double x);
22
23       int isnan(double x);
24       int isnanf(float x);
25       int isnanl(long double x);
26
27   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
28
29       finite(), finitef(), finitel():
30           /* glibc >= 2.19: */ _DEFAULT_SOURCE
31               || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
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33       isinf():
34           _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE
35               || /* glibc >= 2.19: */ _DEFAULT_SOURCE
36               || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
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38       isinff(), isinfl():
39           /* glibc >= 2.19: */ _DEFAULT_SOURCE
40               || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
41
42       isnan():
43           _XOPEN_SOURCE || _ISOC99_SOURCE
44               || /* glibc >= 2.19: */ _DEFAULT_SOURCE
45               || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
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47       isnanf(), isnanl():
48           _XOPEN_SOURCE >= 600
49               || /* glibc >= 2.19: */ _DEFAULT_SOURCE
50               || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
51

DESCRIPTION

53       The finite(), finitef(), and finitel() functions return a nonzero value
54       if x is neither infinite nor a "not-a-number" (NaN) value, and 0 other‐
55       wise.
56
57       The isnan(), isnanf(), and isnanl() functions return a nonzero value if
58       x is a NaN value, and 0 otherwise.
59
60       The isinf(), isinff(), and isinfl() functions return 1 if x is positive
61       infinity, -1 if x is negative infinity, and 0 otherwise.
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ATTRIBUTES

64       For an  explanation  of  the  terms  used  in  this  section,  see  at‐
65       tributes(7).
66
67       ┌────────────────────────────────────────────┬───────────────┬─────────┐
68       │Interface                                   │ Attribute     │ Value   │
69       ├────────────────────────────────────────────┼───────────────┼─────────┤
70       │finite(), finitef(), finitel(), isinf(),    │ Thread safety │ MT-Safe │
71       │isinff(), isinfl(), isnan(), isnanf(),      │               │         │
72       │isnanl()                                    │               │         │
73       └────────────────────────────────────────────┴───────────────┴─────────┘
74

NOTES

76       Note that these functions are obsolete.  C99 defines macros isfinite(),
77       isinf(), and isnan() (for all types) replacing them.  Further note that
78       the C99 isinf() has weaker guarantees on the return value.  See fpclas‐
79       sify(3).
80

SEE ALSO

82       fpclassify(3)
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86Linux man-pages 6.04              2023-02-05                         finite(3)
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