# DragonFly On-Line Manual Pages

FPCLASSIFY(3) DragonFly 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 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.
The symbol **isnanf**() is provided as an alias to **isnan**() for compatibility,
and its use is deprecated. Similarly, **finite**() and **finitef**() are depre-
cated versions of **isfinite**().
## 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

The **fpclassify**(), **isfinite**(), **isinf**(), **isnan**(), and **isnormal**() macros
were added in DragonFly 1.3. 3BSD introduced **isinf**() and **isnan**() func-
tions, which accepted *double* arguments; these have been superseded by the
macros described above.
DragonFly 4.3 January 26, 2005 DragonFly 4.3