FINITE(3)                  Linux Programmer's Manual                 FINITE(3)



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

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 since 2.19: */ _DEFAULT_SOURCE
               || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
       isinf():
           _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE
               || /* Glibc since 2.19: */ _DEFAULT_SOURCE
               || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
       isinff(), isinfl():
           /* Glibc since 2.19: */ _DEFAULT_SOURCE
               || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
       isnan():
           _XOPEN_SOURCE || _ISOC99_SOURCE
               || /* Glibc since 2.19: */ _DEFAULT_SOURCE
               || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
       isnanf(), isnanl():
           _XOPEN_SOURCE >= 600
               || /* Glibc since 2.19: */ _DEFAULT_SOURCE
               || /* Glibc versions <= 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 other-
       wise.

       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).

       allbox;  lbw31  lb  lb  l  l l.  Interface Attribute Value T{ finite(),
       finitef(), finitel(),
       isinf(), isinff(), isinfl(),
       isnan(), isnanf(), isnanl() T}   Thread safety  MT-Safe

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 fpclas-
       sify(3).

SEE ALSO
       fpclassify(3)

COLOPHON
       This  page  is  part of release 4.16 of the Linux man-pages project.  A
       description of the project, information about reporting bugs,  and  the
       latest     version     of     this    page,    can    be    found    at
       https://www.kernel.org/doc/man-pages/.



                                  2017-09-15                         FINITE(3)