1REMAINDER(3) Linux Programmer's Manual REMAINDER(3)
2
6 drem, dremf, dreml, remainder, remainderf, remainderl - floating-point
7 remainder function
8
10 #include <math.h>
11 /* The C99 versions */
13 double remainder(double x, double y);
14 float remainderf(float x, float y);
15 long double remainderl(long double x, long double y);
16 /* Obsolete synonyms */
18 double drem(double x, double y);
19 float dremf(float x, float y);
20 long double dreml(long double x, long double y);
21 Link with -lm.
23 Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
25 remainder():
27 _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
28 || _XOPEN_SOURCE >= 500
29 || /* Since glibc 2.19: */ _DEFAULT_SOURCE
30 || /* Glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
31 remainderf(), remainderl():
33 _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
34 || /* Since glibc 2.19: */ _DEFAULT_SOURCE
35 || /* Glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
36 drem(), dremf(), dreml():
38 /* Since glibc 2.19: */ _DEFAULT_SOURCE
39 || /* Glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
40
42 These functions compute the remainder of dividing x by y. The return
43 value is x-n*y, where n is the value x / y, rounded to the nearest in‐
44 teger. If the absolute value of x-n*y is 0.5, n is chosen to be even.
45 These functions are unaffected by the current rounding mode (see
47 fenv(3)).
48 The drem() function does precisely the same thing.
50
52 On success, these functions return the floating-point remainder, x-n*y.
53 If the return value is 0, it has the sign of x.
54 If x or y is a NaN, a NaN is returned.
56 If x is an infinity, and y is not a NaN, a domain error occurs, and a
58 NaN is returned.
59 If y is zero, and x is not a NaN, a domain error occurs, and a NaN is
61 returned.
62
64 See math_error(7) for information on how to determine whether an error
65 has occurred when calling these functions.
66 The following errors can occur:
68 Domain error: x is an infinity and y is not a NaN
70 errno is set to EDOM (but see BUGS). An invalid floating-point
71 exception (FE_INVALID) is raised.
72 These functions do not set errno for this case.
74 Domain error: y is zero
76 errno is set to EDOM. An invalid floating-point exception
77 (FE_INVALID) is raised.
78
80 For an explanation of the terms used in this section, see at‐
81 tributes(7).
82 ┌────────────────────────────────────────────┬───────────────┬─────────┐
84 │Interface │ Attribute │ Value │
85 ├────────────────────────────────────────────┼───────────────┼─────────┤
86 │drem(), dremf(), dreml(), remainder(), │ Thread safety │ MT-Safe │
87 │remainderf(), remainderl() │ │ │
88 └────────────────────────────────────────────┴───────────────┴─────────┘
89
91 The functions remainder(), remainderf(), and remainderl() are specified
92 in C99, POSIX.1-2001, and POSIX.1-2008.
93 The function drem() is from 4.3BSD. The float and long double variants
95 dremf() and dreml() exist on some systems, such as Tru64 and glibc2.
96 Avoid the use of these functions in favor of remainder() etc.
97
99 Before glibc 2.15, the call
100 remainder(nan(""), 0);
102 returned a NaN, as expected, but wrongly caused a domain error. Since
104 glibc 2.15, a silent NaN (i.e., no domain error) is returned.
105 Before glibc 2.15, errno was not set to EDOM for the domain error that
107 occurs when x is an infinity and y is not a NaN.
108
110 The call "remainder(29.0, 3.0)" returns -1.
111
113 div(3), fmod(3), remquo(3)
114
116 This page is part of release 5.12 of the Linux man-pages project. A
117 description of the project, information about reporting bugs, and the
118 latest version of this page, can be found at
119 https://www.kernel.org/doc/man-pages/.
120 2021-03-22 REMAINDER(3)