xref: /openbsd/lib/libm/man/remainder.3 (revision 3d8817e4)
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30.\"     from: @(#)ieee.3	6.4 (Berkeley) 5/6/91
31.\" $FreeBSD: src/lib/msun/man/remainder.3,v 1.6 2008/03/30 20:48:02 das Exp $
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33.Dd $Mdocdate: March 26 2010 $
34.Dt REMAINDER 3
35.Os
36.Sh NAME
37.Nm remainder ,
38.Nm remainderf ,
39.Nm remquo ,
40.Nm remquof
41.Nd minimal residue functions
42.Sh SYNOPSIS
43.In math.h
44.Ft double
45.Fn remainder "double x" "double y"
46.Ft float
47.Fn remainderf "float x" "float y"
48.Ft double
49.Fn remquo "double x" "double y" "int *quo"
50.Ft float
51.Fn remquof "float x" "float y" "int *quo"
52.Sh DESCRIPTION
53.Fn remainder ,
54.Fn remainderf ,
55.Fn remquo ,
56and
57.Fn remquof
58return the remainder
59.Fa r
60:=
61.Fa x
62\-
63.Fa n\(**y
64where
65.Fa n
66is the integer nearest the exact value of
67.Bk -words
68.Fa x Ns / Ns Fa y ;
69.Ek
70moreover if
71.Pf \*(Ba Fa n
72\-
73.Sm off
74.Fa x No / Fa y No \*(Ba
75.Sm on
76=
771/2
78then
79.Fa n
80is even.
81Consequently
82the remainder is computed exactly and
83.Sm off
84.Pf \*(Ba Fa r No \*(Ba
85.Sm on
86\*(Le
87.Sm off
88.Pf \*(Ba Fa y No \*(Ba/2 .
89.Sm on
90But attempting to take the remainder when
91.Fa y
92is 0 or
93.Fa x
94is \*(Pm\*(If is an invalid operation that produces a \*(Na.
95.Pp
96The
97.Fn remquo
98and
99.Fn remquof
100functions also store the last
101.Va k
102bits of
103.Fa n
104in the location pointed to by
105.Fa quo ,
106provided that
107.Fa n
108exists.
109The number of bits
110.Va k
111is platform-specific, but is guaranteed to be at least 3.
112.Sh SEE ALSO
113.Xr fmod 3 ,
114.Xr math 3 ,
115.Xr nextafter 3
116.Sh STANDARDS
117The
118.Fn remainder ,
119.Fn remainderf ,
120.Fn remquo ,
121and
122.Fn remquof
123routines conform to
124.St -isoC-99 .
125The remainder is as defined in
126.St -ieee754 .
127.Pp
128.Fn drem
129and
130.Fn dremf
131are deprecated aliases for
132.Fn remainder
133and
134.Fn remainderf ,
135respectively.
136.Sh HISTORY
137The
138.Fn remainder
139and
140.Fn remainderf
141functions appeared in
142.Bx 4.3
143and
144.Nx 1.2 ,
145respectively.
146The
147.Fn remquo
148and
149.Fn remquof
150functions were added in
151.Ox 4.4 .
152