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



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

SYNOPSIS
       #define _ISOC99_SOURCE
       #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, respec-
       tively, that represent a large positive value, possibly plus infinity.

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_VERSION__ is defined and has a value not less than 199901L.

SEE ALSO
       fpclassify(3), feature_test_macros(7), math_error(7)

COLOPHON
       This  page  is part of release 3.22 of the Linux man-pages project.  A description of the project, and informa-
       tion about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.



                                  2007-07-26                       INFINITY(3)