freebsd-dev/lib/libc/gen/fpclassify.3
David Schultz 29bf6af890 - Move the functions presently described in in ieee(3) to their own
manpages.  They are not very related, so separating them makes it
  easier to add meaningful cross-references and extend some of the
  descriptions.
- Move the part of math(3) that discusses IEEE 754 to the ieee(3)
  manpage.
2005-01-27 05:46:17 +00:00

134 lines
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.\" Copyright (c) 2003 Mike Barcroft <mike@FreeBSD.org>
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.Dd January 26, 2005
.Dt FPCLASSIFY 3
.Os
.Sh NAME
.Nm fpclassify , isfinite , isinf , isnan , isnormal
.Nd "classify a floating-point number"
.Sh LIBRARY
.Lb libm
.Sh SYNOPSIS
.In math.h
.Ft int
.Fn fpclassify "real-floating x"
.Ft int
.Fn isfinite "real-floating x"
.Ft int
.Fn isinf "real-floating x"
.Ft int
.Fn isnan "real-floating x"
.Ft int
.Fn isnormal "real-floating x"
.Sh DESCRIPTION
The
.Fn fpclassify
macro takes an argument of
.Fa x
and returns one of the following manifest constants.
.Bl -tag -width ".Dv FP_SUBNORMAL"
.It Dv FP_INFINITE
Indicates that
.Fa x
is an infinite number.
.It Dv FP_NAN
Indicates that
.Fa x
is not a number (NaN).
.It Dv FP_NORMAL
Indicates that
.Fa x
is a normalized number.
.It Dv FP_SUBNORMAL
Indicates that
.Fa x
is a denormalized number.
.It Dv FP_ZERO
Indicates that
.Fa x
is zero (0 or \-0).
.El
.Pp
The
.Fn isfinite
macro returns a non-zero value if and only if its argument has
a finite (zero, subnormal, or normal) value.
The
.Fn isinf ,
.Fn isnan ,
and
.Fn isnormal
macros return non-zero if and only if
.Fa x
is an infinity, NaN,
or a non-zero normalized number, respectively.
.Pp
The symbol
.Fn isnanf
is provided as an alias to
.Fn isnan
for compatibility, and its use is deprecated.
Similarly,
.Fn finite
and
.Fn finitef
are deprecated versions of
.Fn isfinite .
.Sh SEE ALSO
.Xr isgreater 3 ,
.Xr math 3 ,
.Xr signbit 3
.Sh STANDARDS
The
.Fn fpclassify ,
.Fn isfinite ,
.Fn isinf ,
.Fn isnan ,
and
.Fn isnormal
macros conform to
.St -isoC-99 .
.Sh HISTORY
The
.Fn fpclassify ,
.Fn isfinite ,
.Fn isinf ,
.Fn isnan ,
and
.Fn isnormal
macros were added in
.Fx 5.1 .
.Bx 3
introduced
.Fn isinf
and
.Fn isnan
functions, which accepted
.Vt double
arguments; these have been superseded by the macros
described above.