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



NAME
       INFINITY, NAN, HUGE_VAL, HUGE_VALF, HUGE_VALL - floating-point constants

SYNOPSIS
       #define _ISOC99_SOURCE      /* See feature_test_macros(7) */
       #include <math.h>

       INFINITY

       NAN

       HUGE_VAL
       HUGE_VALF
       HUGE_VALL

DESCRIPTION
       The macro INFINITY expands to a float constant representing positive infinity.

       The  macro  NAN  expands to a float constant representing a quiet NaN (when supported).  A
       quiet NaN is a NaN ("not-a-number") that does not raise exceptions  when  it  is  used  in
       arithmetic.  The opposite is a signaling NaN.  See IEC 60559:1989.

       The  macros  HUGE_VAL, HUGE_VALF, HUGE_VALL expand to constants of types double, float and
       long double, respectively, that represent a large positive value, possibly positive infin‐
       ity.

CONFORMING TO
       C99.

AVAILABILITY
       On  a glibc system, the macro HUGE_VAL is always available.  Availability of the NAN macro
       can be tested using #ifdef NAN, and similarly for INFINITY,  HUGE_VALF,  HUGE_VALL.   They
       will  be  defined  by <math.h> if _ISOC99_SOURCE or _GNU_SOURCE is defined, or __STDC_VER‐
       SION__ is defined and has a value not less than 199901L.

SEE ALSO
       fpclassify(3), math_error(7)

COLOPHON
       This page is part of release 3.74 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 http://www.kernel.org/doc/man-pages/.



                                            2007-07-26                                INFINITY(3)