1 .\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
3 .\" %%%LICENSE_START(GPL_NOVERSION_ONELINE)
4 .\" Distributed under GPL
7 .\" This was done with the help of the glibc manual.
9 .\" 2004-10-31, aeb, corrected
10 .TH FPCLASSIFY 3 2013-08-06 "" "Linux Programmer's Manual"
12 fpclassify, isfinite, isnormal, isnan, isinf \- floating-point
18 .BI "int fpclassify(" x );
20 .BI "int isfinite(" x );
22 .BI "int isnormal(" x );
32 Feature Test Macro Requirements for glibc (see
33 .BR feature_test_macros (7)):
36 .\" I haven't fully grokked the source to determine the FTM requirements;
37 .\" in part, the following has been tested by experiment.
43 _XOPEN_SOURCE\ >=\ 600 || _ISOC99_SOURCE ||
44 _POSIX_C_SOURCE\ >=\ 200112L;
51 _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE || _ISOC99_SOURCE ||
52 _POSIX_C_SOURCE\ >=\ 200112L;
59 _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE\ >=\ 600 || _ISOC99_SOURCE ||
60 _POSIX_C_SOURCE\ >=\ 200112L;
67 Floating point numbers can have special values, such as
71 you can find out what type
74 The macro takes any floating-point expression as argument.
75 The result is one of the following values:
83 is either positive infinity or negative infinity.
91 is too small to be represented in normalized format.
94 if nothing of the above is correct then it must be a
95 normal floating-point number.
97 The other macros provide a short answer to some standard questions.
100 returns a nonzero value if
102 (fpclassify(x) != FP_NAN && fpclassify(x) != FP_INFINITE)
105 returns a nonzero value if
106 (fpclassify(x) == FP_NORMAL)
109 returns a nonzero value if
110 (fpclassify(x) == FP_NAN)
115 is positive infinity, and \-1 if
117 is negative infinity.
119 .SS Multithreading (see pthreads(7))
127 macros are thread-safe.
133 the standards merely say that the return value is nonzero
134 if and only if the argument has an infinite value.
136 In glibc 2.01 and earlier,
138 returns a nonzero value (actually: 1) if
140 is positive infinity or negative infinity.
141 (This is all that C99 requires.)