finite(3)                  Library Functions Manual                  finite(3)

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

LIBRARY
       Math library (libm, -lm)

SYNOPSIS
       #include <math.h>

       int finite(double x);
       int finitef(float x);
       int finitel(long double x);

       int isinf(double x);
       int isinff(float x);
       int isinfl(long double x);

       int isnan(double x);
       int isnanf(float x);
       int isnanl(long double x);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       finite(), finitef(), finitel():
           /* glibc >= 2.19: */ _DEFAULT_SOURCE
               || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

       isinf():
           _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE
               || /* glibc >= 2.19: */ _DEFAULT_SOURCE
               || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

       isinff(), isinfl():
           /* glibc >= 2.19: */ _DEFAULT_SOURCE
               || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

       isnan():
           _XOPEN_SOURCE || _ISOC99_SOURCE
               || /* glibc >= 2.19: */ _DEFAULT_SOURCE
               || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

       isnanf(), isnanl():
           _XOPEN_SOURCE >= 600
               || /* glibc >= 2.19: */ _DEFAULT_SOURCE
               || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

DESCRIPTION
       The finite(), finitef(), and finitel() functions return a nonzero value
       if x is neither infinite nor a "not-a-number" (NaN) value, and 0
       otherwise.

       The isnan(), isnanf(), and isnanl() functions return a nonzero value if
       x is a NaN value, and 0 otherwise.

       The isinf(), isinff(), and isinfl() functions return 1 if x is positive
       infinity, -1 if x is negative infinity, and 0 otherwise.

ATTRIBUTES
       For an explanation of the terms used in this section, see
       attributes(7).

       +--------------------------------------------+---------------+---------+
       |Interface                                   | Attribute     | Value   |
       +--------------------------------------------+---------------+---------+
       |finite (), finitef (), finitel (), isinf    | Thread safety | MT-Safe |
       |(), isinff (), isinfl (), isnan (), isnanf  |               |         |
       |(), isnanl ()                               |               |         |
       +--------------------------------------------+---------------+---------+
NOTES
       Note that these functions are obsolete.  C99 defines macros isfinite(),
       isinf(), and isnan() (for all types) replacing them.  Further note that
       the C99 isinf() has weaker guarantees on the return value.  See
       fpclassify(3).

SEE ALSO
       fpclassify(3)

Linux man-pages 6.7               2023-10-31                         finite(3)