class(3C)

NAME
     fpclassify, isfinite, isinf, isnan, isnormal, signbit, fpclassifyf,
     isfinitef, isinff, isnanf, isnormalf, signbitf, fpclassifyl, isfinitel,
     isinfl, isnanl, isnormall, signbitl,
      - classification macros (and functions)

SYNOPSIS
     #include <math.h>

     int fpclassify(real-floating x);
     int isfinite(real-floating x);
     int isinf(real-floating x);
     int isnan(real-floating x);
     int isnormal(real-floating x);
     int signbit(real-floating x);

DESCRIPTION
     These macros (and functions) are not available for programs compiled with
     the O32 ABI.

     These macros are implemented in terms of ordinary functions depending on
     the argument used; for example, if x is a float expression, the macro
     fpclassify generates a call to the function fpclassifyf.  If x is a
     double expression, the macro generates a call to the function fpclassify.
     If x is a long double expression, the macro generates a call to the
     function fpclassifyl.

     The fpclassify macro returns the value of the number classification macro
     appropriate to the value of its argument.  Possible return values are
     FP_ZERO, FP_SUBNORMAL, FP_NORMAL, FP_INFINITE, and FP_NAN, whose values
     are defined in math.h.

     The isfinite macro returns a non-zero value if and only if its argument
     has a finite value.

     The isinf macro returns a nonzero value if and only if its argument has
     an infinite value.

     The isnan macro returns a nonzero value if and only if its argument is a
     NaN (not-a-number)

     The isnormal macro returns a nonzero value if and only if its argument
     has a normal value according to IEEE floating point definitions.

     The signbit macro returns a nonzero value if and only if the sign of its
     argument value is negative.

NOTES
     Long double operations on this system are only supported in round to
     nearest rounding mode (the default). The system must be in round to
     nearest rounding mode when calling any of the long double functions, or
     incorrect answers will result.
SEE ALSO
     math(3M), frexp(3C)