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



NAME
       INFINITY,  NAN,  HUGE_VAL,  HUGE_VALF,  HUGE_VALL - floating-point con-
       stants

SYNOPSIS
       #define _ISOC99_SOURCE
       #include <&lt;math.h>&gt;

       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 sig-
       naling 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 plus infinity.

CONFORMING TO
       C99.

AVAILABILITY
       On a glibc system, the macro HUGE_VAL is always available.   Availabil-
       ity  of the NAN macro can be tested using #ifdef NAN, and similarly for
       INFINITY, HUGE_VALF, HUGE_VALL.  They will be defined  by  &lt;math.h&gt;  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 3.05 of the Linux  man-pages  project.   A
       description  of  the project, and information about reporting bugs, can
       be found at http://www.kernel.org/doc/man-pages/.



                                  2007-07-26                       INFINITY(3)