1INFINITY(3)                Linux Programmer's Manual               INFINITY(3)
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NAME

6       INFINITY,  NAN,  HUGE_VAL,  HUGE_VALF,  HUGE_VALL - floating point con‐
7       stants
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SYNOPSIS

10       #define _ISOC99_SOURCE
11       #include <math.h>
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13       INFINITY
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15       NAN
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17       HUGE_VAL
18       HUGE_VALF
19       HUGE_VALL
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DESCRIPTION

22       The macro INFINITY expands to a float  constant  representing  positive
23       infinity.
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25       The  macro  NAN  expands  to  a float constant representing a quiet NaN
26       (when supported). A quiet NaN is a NaN ("not-a-number") that  does  not
27       raise  exceptions when it is used in arithmetic. The opposite is a sig‐
28       nalling NaN. See IEC 60559:1989.
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30       The macros HUGE_VAL, HUGE_VALF, HUGE_VALL expand to constants of  types
31       double,  float  and  long  double, respectively, that represent a large
32       positive value, possibly plus infinity.
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AVAILABILITY

36       On a glibc system, the macro HUGE_VAL is always available.   Availabil‐
37       ity  of the NAN macro can be tested using #ifdef NAN, and similarly for
38       INFINITY, HUGE_VALF, HUGE_VALL.  They will be defined  by  <math.h>  if
39       _ISOC99_SOURCE  or  _GNU_SOURCE  is  defined,  or  __STDC_VERSION__  is
40       defined and has a value not less than 199901L.
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CONFORMING TO

44       C99
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SEE ALSO

47       fpclassify(3), feature_test_macros(7)
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51                                  2004-10-31                       INFINITY(3)