FPCLASIFY(3)            BSD Library Functions Manual            FPCLASIFY(3)

NAME
     fpclassify, isfinite, isinf, isnan, isnormal -- classify a floating-point
     number

LIBRARY
     Math Library (libm, -lm)

SYNOPSIS
     ##include <>

     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);

DESCRIPTION
     The fpclassify() macro takes an argument of x and returns one of the fol-
     lowing manifest constants.

     FPINFINITE   Indicates that x is an infinite number.

     FPNAN        Indicates that x is not a number (NaN).

     FPNORMAL     Indicates that x is a normalized number.

     FPSUBNORMAL  Indicates that x is a denormalized number.

     FPZERO       Indicates that x is zero (0 or -0).

     The isfinite() macro returns a non-zero value if and only if its argument
     has a finite (zero, subnormal, or normal) value.  The isinf(), isnan(),
     and isnormal() macros return non-zero if and only if x is an infinity,
     NaN, or a non-zero normalized number, respectively.

     The symbol isnanf() is provided as an alias to isnan() for compatibility,
     and its use is deprecated.

SEE ALSO
     isgreater(3), math(3), signbit(3)

STANDARDS
     The fpclassify(), isfinite(), isinf(), isnan(), and isnormal() macros
     conform to ISO/IEC 9899:1999 (``ISO C99'').

HISTORY
     3BSD introduced isinf() and isnan() functions, which accepted double
     arguments; these have been superseded by the macros described above.

BSD                              July 8, 2004                              BSD