isnan(3C)

NAME
     isnan, isnand, isnanf, finite, fpclass, unordered, isnanl, finitel,
     fpclassl, unorderedl - determine type of floating-point number

SYNOPSIS
     #include <ieeefp.h>

     int isnand (double dsrc);

     int isnanf (float fsrc);

     int finite (double dsrc);

     fpclass_t fpclass (double dsrc);

     int unordered (double dsrc1, double dsrc2);

     fpclass_t fpclassl (long double dsrc);

     int finitel (long double dsrc);

     int unorderedl (long double dsrc1, long double dsrc2);

     #include <math.h>

     int isnan (double dsrc);

     int isnanl (long double dsrc);

DESCRIPTION
     (Note that the long double routines are only valid for the MIPSpro
     compilers.)  Long double functions have been renamed to be compliant with
     the ANSI-C standard, however to be backward compatible, they may still be
     called with the double precision function name prefixed with a q.
     (Exception:  function isnanl may be called with the name isnanq.)

     isnan, isnand, isnanf, and isnanl return true (1) if the argument dsrc or
     fsrc is a NaN; otherwise they return false (0).  The functionality of
     isnan is identical to that of isnand.

     fpclass and fpclassl return the class the dsrc belongs to.  The 10
     possible classes are as follows:
          FP_SNAN      signaling NaN
          FP_QNAN      quiet NaN
          FP_NINF      negative infinity
          FP_PINF      positive infinity
          FP_NDENORM   negative denormalized non-zero
          FP_PDENORM   positive denormalized non-zero
          FP_NZERO     negative zero
          FP_PZERO     positive zero
          FP_NNORM     negative normalized non-zero
          FP_PNORM     positive normalized non-zero

     In the case of long doubles, non-zero numbers less than 2**-916 in
     absolute value are classified as denormalized, since one of the numbers
     used in their representation may be a denormal double.

     finite and finitel return true (1) if the argument dsrc is neither
     infinity nor NaN; otherwise they return false (0).

     unordered and unorderedl return true (1) if one of their two arguments is
     unordered with respect to the other argument.  This is equivalent to
     reporting whether either argument is NaN.  If neither of the arguments is
     NaN, false (0) is returned.

     None of these routines generate any exceptions, even for signaling NaNs.

     Note that the SVR4 function fpclass is distinct from the functions
     documented in fp_class(3C).

SEE ALSO
     fpgetround(3C), fp_class(3C), intro(3M).