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(), isinff(), isinfl(),   │ Thread safety │ MT-Safe │
       │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)