1.\" Copyright (c) 1985, 1991 Regents of the University of California.
2.\" All rights reserved.
3.\"
4.\" Redistribution and use in source and binary forms, with or without
5.\" modification, are permitted provided that the following conditions
6.\" are met:
7.\" 1. Redistributions of source code must retain the above copyright
8.\" notice, this list of conditions and the following disclaimer.
--- 12 unchanged lines hidden (view full) ---
21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26.\" SUCH DAMAGE.
27.\"
28.\" from: @(#)ieee.3 6.4 (Berkeley) 5/6/91
29.\" $FreeBSD: head/lib/msun/man/ilogb.3 165906 2007-01-09 01:02:06Z imp $
30.\"
31.Dd November 6, 2005
32.Dt ILOGB 3
33.Os
34.Sh NAME
35.Nm ilogb ,
36.Nm ilogbf ,
37.Nm ilogbl ,
38.Nm logb ,
39.Nm logbf
40.Nd extract exponent
41.Sh LIBRARY
42.Lb libm
43.Sh SYNOPSIS
44.In math.h
45.Ft int
46.Fn ilogb "double x"
47.Ft int
48.Fn ilogbf "float x"
49.Ft int
50.Fn ilogbl "long double x"
51.Ft double
52.Fn logb "double x"
53.Ft float
54.Fn logbf "float x"
55.Sh DESCRIPTION
56.Fn ilogb ,
57.Fn ilogbf
58and
59.Fn ilogbl
60return
61.Fa x Ns 's exponent
62in integer format.
63.Fn ilogb \*(Pm\*(If
64returns
65.Dv INT_MAX ,
66.Fn ilogb \*(Pm\*(Na
67returns
68.Dv FP_ILOGBNAN ,
69and
70.Fn ilogb 0
71returns
72.Dv FP_ILOGB0 .
73.Pp
74.Fn logb x
75and
76.Fn logbf x
77return
78.Fa x Ns 's exponent
79in floating\-point format with the same precision as
80.Fa x .
81.Fn logb \*(Pm\*(If
82returns +\*(If, and
83.Fn logb 0
84returns -\*(If with a division by zero exception.
85.Sh SEE ALSO
86.Xr frexp 3 ,
87.Xr ieee 3 ,
88.Xr math 3 ,
89.Xr scalbn 3
90.Sh STANDARDS
91The
92.Fn ilogb ,
93.Fn ilogbf ,
94.Fn ilogbl ,
95.Fn logb
96and
97.Fn logbf
98routines conform to
99.St -isoC-99 .
100.Fn logb
101and
102.Fn logbf
103implement the logb function recommended by
104.St -ieee754 .
105.Sh HISTORY
106The
107.Fn logb
108function appeared in
109.Bx 4.3 .
110The
111.Fn ilogb
112function appeared in
113.Fx 1.1.5 .
114The
115.Fn ilogbf
116and
117.Fn logbf
118functions appeared in
119.Fx 2.0 .
120The
121.Fn ilogbl
122function appeared in
123.Fx 5.4 .
2.\" All rights reserved.
3.\"
4.\" Redistribution and use in source and binary forms, with or without
5.\" modification, are permitted provided that the following conditions
6.\" are met:
7.\" 1. Redistributions of source code must retain the above copyright
8.\" notice, this list of conditions and the following disclaimer.
--- 12 unchanged lines hidden (view full) ---
21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26.\" SUCH DAMAGE.
27.\"
28.\" from: @(#)ieee.3 6.4 (Berkeley) 5/6/91
29.\" $FreeBSD: head/lib/msun/man/ilogb.3 165906 2007-01-09 01:02:06Z imp $
30.\"
31.Dd November 6, 2005
32.Dt ILOGB 3
33.Os
34.Sh NAME
35.Nm ilogb ,
36.Nm ilogbf ,
37.Nm ilogbl ,
38.Nm logb ,
39.Nm logbf
40.Nd extract exponent
41.Sh LIBRARY
42.Lb libm
43.Sh SYNOPSIS
44.In math.h
45.Ft int
46.Fn ilogb "double x"
47.Ft int
48.Fn ilogbf "float x"
49.Ft int
50.Fn ilogbl "long double x"
51.Ft double
52.Fn logb "double x"
53.Ft float
54.Fn logbf "float x"
55.Sh DESCRIPTION
56.Fn ilogb ,
57.Fn ilogbf
58and
59.Fn ilogbl
60return
61.Fa x Ns 's exponent
62in integer format.
63.Fn ilogb \*(Pm\*(If
64returns
65.Dv INT_MAX ,
66.Fn ilogb \*(Pm\*(Na
67returns
68.Dv FP_ILOGBNAN ,
69and
70.Fn ilogb 0
71returns
72.Dv FP_ILOGB0 .
73.Pp
74.Fn logb x
75and
76.Fn logbf x
77return
78.Fa x Ns 's exponent
79in floating\-point format with the same precision as
80.Fa x .
81.Fn logb \*(Pm\*(If
82returns +\*(If, and
83.Fn logb 0
84returns -\*(If with a division by zero exception.
85.Sh SEE ALSO
86.Xr frexp 3 ,
87.Xr ieee 3 ,
88.Xr math 3 ,
89.Xr scalbn 3
90.Sh STANDARDS
91The
92.Fn ilogb ,
93.Fn ilogbf ,
94.Fn ilogbl ,
95.Fn logb
96and
97.Fn logbf
98routines conform to
99.St -isoC-99 .
100.Fn logb
101and
102.Fn logbf
103implement the logb function recommended by
104.St -ieee754 .
105.Sh HISTORY
106The
107.Fn logb
108function appeared in
109.Bx 4.3 .
110The
111.Fn ilogb
112function appeared in
113.Fx 1.1.5 .
114The
115.Fn ilogbf
116and
117.Fn logbf
118functions appeared in
119.Fx 2.0 .
120The
121.Fn ilogbl
122function appeared in
123.Fx 5.4 .