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FPCLASSIFY(3)            BSD Library Functions Manual            FPCLASSIFY(3)

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

LIBRARY
     Math Library (libm, -lm)

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);

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

     FP_INFINITE   Indicates that x is an infinite number.

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

     FP_NORMAL     Indicates that x is a normalized number.

     FP_SUBNORMAL  Indicates that x is a denormalized number.

     FP_ZERO       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.

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     arguments; these have been superseded by the macros described above.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