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
       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), math_error(7)

COLOPHON

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       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)