[thirdparty/man-pages.git] / man3 / fpclassify.3

.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
.\" Distributed under GPL, 2002-07-27 Walter Harms
.\" This was done with the help of the glibc manual.
.\"
.\" 2004-10-31, aeb, corrected
.TH FPCLASSIFY 3  2007-07-26 "" "Linux Programmer's Manual"
.SH NAME
fpclassify, isfinite, isnormal, isnan, isinf \- floating-point
classification macros
.SH SYNOPSIS
.nf
.B #include <math.h>
.sp
.BI "int fpclassify(" x );
.sp
.BI "int isfinite(" x );
.sp
.BI "int isnormal(" x );
.sp
.BI "int isnan(" x );
.sp
.BI "int isinf(" x );
.fi
.sp
Link with \fI\-lm\fP.
.sp
.in -4n
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.in
.sp
.\" I haven't fully grokked the source to determine the FTM requirements;
.\" in part, the following has been tested by experiment.
.ad l
.BR fpclassify (),
.BR isfinite (),
.BR isnormal ():
_XOPEN_SOURCE\ >=\ 600 || _ISOC99_SOURCE; or
.I cc\ -std=c99
.br
.BR isnan ():
_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE || _ISOC99_SOURCE; or
.I cc\ -std=c99
.br
.BR isinf ():
_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE\ >=\ 600 || _ISOC99_SOURCE; or
.I cc\ -std=c99
.ad b
.SH DESCRIPTION
Floating point numbers can have special values, such as
infinite or NaN.
With the macro
.BI fpclassify( x )
you can find out what type
.I x
is.
The macro takes any floating-point expression as argument.
The result is one of the following values:
.TP
.B FP_NAN
.I x
is "Not a Number".
.TP
.B FP_INFINITE
.I x
is either plus or minus infinity.
.TP
.B FP_ZERO
.I x
is zero.
.TP
.B FP_SUBNORMAL
.I x
is too small to be represented in normalized format.
.TP
.B FP_NORMAL
if nothing of the above is correct then it must be a
normal floating-point number.
.LP
The other macros provide a short answer to some standard questions.
.TP
.BI isfinite( x )
returns a non-zero value if
.br
(fpclassify(x) != FP_NAN && fpclassify(x) != FP_INFINITE)
.TP
.BI isnormal( x )
returns a non-zero value if
(fpclassify(x) == FP_NORMAL)
.TP
.BI isnan( x )
returns a non-zero value if
(fpclassify(x) == FP_NAN)
.TP
.BI isinf( x )
returns 1 if
.I x
is positive infinity, and \-1 if
.I x
is negative infinity.
.SH "CONFORMING TO"
C99
.SH NOTES
In glibc 2.01 and earlier,
.BR isinf ()
returns a non-zero value (actually: 1) if
.I x
is an infinity (positive or negative).
(This is all that C99 requires.)
.SH "SEE ALSO"
.BR finite (3),
.BR INFINITY (3),
.BR isgreater (3)
Commit	Line	Data
fea681da MK	1	.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
	2	.\" Distributed under GPL, 2002-07-27 Walter Harms
	3	.\" This was done with the help of the glibc manual.
	4	.\"
	5	.\" 2004-10-31, aeb, corrected
cc4615cc	6	.TH FPCLASSIFY 3 2007-07-26 "" "Linux Programmer's Manual"
fea681da	7	.SH NAME
2fd7b9d4 MK	8	fpclassify, isfinite, isnormal, isnan, isinf \- floating-point
2fd7b9d4 MK	9	classification macros
fea681da MK	10	.SH SYNOPSIS
	11	.nf
	12	.B #include <math.h>
	13	.sp
	14	.BI "int fpclassify(" x );
	15	.sp
	16	.BI "int isfinite(" x );
	17	.sp
	18	.BI "int isnormal(" x );
	19	.sp
	20	.BI "int isnan(" x );
	21	.sp
	22	.BI "int isinf(" x );
	23	.fi
462a7bad	24	.sp
cc4615cc MK	25	Link with \fI\-lm\fP.
	26	.sp
	27	.in -4n
	28	Feature Test Macro Requirements for glibc (see
	29	.BR feature_test_macros (7)):
	30	.in
	31	.sp
	32	.\" I haven't fully grokked the source to determine the FTM requirements;
	33	.\" in part, the following has been tested by experiment.
	34	.ad l
	35	.BR fpclassify (),
	36	.BR isfinite (),
	37	.BR isnormal ():
	38	_XOPEN_SOURCE\ >=\ 600 \|\| _ISOC99_SOURCE; or
	39	.I cc\ -std=c99
	40	.br
	41	.BR isnan ():
	42	_BSD_SOURCE \|\| _SVID_SOURCE \|\| _XOPEN_SOURCE \|\| _ISOC99_SOURCE; or
	43	.I cc\ -std=c99
	44	.br
	45	.BR isinf ():
	46	_BSD_SOURCE \|\| _SVID_SOURCE \|\| _XOPEN_SOURCE\ >=\ 600 \|\| _ISOC99_SOURCE; or
	47	.I cc\ -std=c99
	48	.ad b
fea681da MK	49	.SH DESCRIPTION
fea681da MK	50	Floating point numbers can have special values, such as
1c44bd5b MK	51	infinite or NaN.
1c44bd5b MK	52	With the macro
c13182ef	53	.BI fpclassify( x )
fea681da MK	54	you can find out what type
fea681da MK	55	.I x
1c44bd5b MK	56	is.
1c44bd5b MK	57	The macro takes any floating-point expression as argument.
c13182ef	58	The result is one of the following values:
fea681da	59	.TP
b20979f0	60	.B FP_NAN
fea681da MK	61	.I x
	62	is "Not a Number".
	63	.TP
b20979f0	64	.B FP_INFINITE
fea681da MK	65	.I x
fea681da MK	66	is either plus or minus infinity.
c13182ef	67	.TP
b20979f0	68	.B FP_ZERO
fea681da MK	69	.I x
	70	is zero.
	71	.TP
b20979f0	72	.B FP_SUBNORMAL
fea681da MK	73	.I x
	74	is too small to be represented in normalized format.
	75	.TP
b20979f0	76	.B FP_NORMAL
6dff8403	77	if nothing of the above is correct then it must be a
fea681da MK	78	normal floating-point number.
	79	.LP
	80	The other macros provide a short answer to some standard questions.
	81	.TP
	82	.BI isfinite( x )
eba72288	83	returns a non-zero value if
fea681da MK	84	.br
	85	(fpclassify(x) != FP_NAN && fpclassify(x) != FP_INFINITE)
	86	.TP
	87	.BI isnormal( x )
eba72288	88	returns a non-zero value if
fea681da MK	89	(fpclassify(x) == FP_NORMAL)
	90	.TP
	91	.BI isnan( x )
eba72288	92	returns a non-zero value if
fea681da MK	93	(fpclassify(x) == FP_NAN)
	94	.TP
	95	.BI isinf( x )
3243fedf MK	96	returns 1 if
	97	.I x
	98	is positive infinity, and \-1 if
	99	.I x
	100	is negative infinity.
2b2581ee MK	101	.SH "CONFORMING TO"
2b2581ee MK	102	C99
19c98696	103	.SH NOTES
3243fedf	104	In glibc 2.01 and earlier,
63aa9df0	105	.BR isinf ()
eba72288	106	returns a non-zero value (actually: 1) if
3243fedf MK	107	.I x
	108	is an infinity (positive or negative).
	109	(This is all that C99 requires.)
fea681da MK	110	.SH "SEE ALSO"
	111	.BR finite (3),
	112	.BR INFINITY (3),
	113	.BR isgreater (3)