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

       For an explanation of the terms used in this section, see attributes(7).
       ┌─────────────────────────────────────────────────────────────────────────────┬───────────────┬─────────┐
       │ Interface                                                                   │ Attribute     │ Value   │
       ├─────────────────────────────────────────────────────────────────────────────┼───────────────┼─────────┤
       │ finite(), finitef(), finitel(), isinf(), isinff(), isinfl(), isnan(),       │ Thread safety │ MT-Safe │
       │ isnanf(), isnanl()                                                          │               │         │
       └─────────────────────────────────────────────────────────────────────────────┴───────────────┴─────────┘

       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.

       Math library (libm, -lm)

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

       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).

fpclassify(3)

Linux man-pages 6.9.1                              2024-05-02                                          finite(3)

#include<math.h>intfinite(doublex);intfinitef(floatx);intfinitel(longdoublex);intisinf(doublex);intisinff(floatx);intisinfl(longdoublex);intisnan(doublex);intisnanf(floatx);intisnanl(longdoublex);

   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