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(), isnan(),         │ Thread safety │ MT-Safe │
       │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)