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NAN(2)                        System Calls Manual                       NAN(2)



NAME
       NaN, Inf, isNaN, isInf - not-a-number and infinity functions

SYNOPSIS
       #include <u.h>
       #include <libc.h>

       double NaN(void)

       double Inf(int)

       int    isNaN(double)

       int    isInf(double, int)

DESCRIPTION
       The  IEEE  floating point standard defines values called `not-a-number'
       and positive and negative `infinity'.  These values can be produced  by
       such  things as overflow and division by zero.  Also, the library func‐
       tions sometimes return them when the arguments are not in  the  domain,
       or  the  result is out of range.  By default, manipulating these values
       may cause a floating point exception on some processors but setfcr (see
       getfcr(2)) can change that behavior.

       NaN  returns  a double that is not-a-number.  IsNaN returns true if its
       argument is not-a-number.

       Inf(i) returns positive infinity if i is greater than or equal to zero,
       else  negative  infinity.   IsInf returns true if its first argument is
       infinity with the same sign as the second argument.

SOURCE
       /sys/src/libc/port/nan.c

SEE ALSO
       getfcr(2)



                                                                        NAN(2)