NAME
fpclassify,
isfinite, isinf,
isnan, isnormal —
classify a floating-point
number
LIBRARY
library “libm”
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
Thefpclassify()
macro takes an argument of x and returns one of the
following 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 deprecated versions of isfinite().
SEE ALSO
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 FreeBSD 5.1.
3BSD introduced isinf() and
isnan() functions, which accepted
double arguments; these have been superseded by the
macros described above.