1REMAINDER(3) Linux Programmer's Manual REMAINDER(3)
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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 versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
31 remainderf(), remainderl():
32 _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
33 || /* Since glibc 2.19: */ _DEFAULT_SOURCE
34 || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
35 drem(), dremf(), dreml():
36 /* Since glibc 2.19: */ _DEFAULT_SOURCE
37 || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
38
40 These functions compute the remainder of dividing x by y. The return
41 value is x-n*y, where n is the value x / y, rounded to the nearest in‐
42 teger. If the absolute value of x-n*y is 0.5, n is chosen to be even.
43 These functions are unaffected by the current rounding mode (see
45 fenv(3)).
46 The drem() function does precisely the same thing.
48
50 On success, these functions return the floating-point remainder, x-n*y.
51 If the return value is 0, it has the sign of x.
52 If x or y is a NaN, a NaN is returned.
54 If x is an infinity, and y is not a NaN, a domain error occurs, and a
56 NaN is returned.
57 If y is zero, and x is not a NaN, a domain error occurs, and a NaN is
59 returned.
60
62 See math_error(7) for information on how to determine whether an error
63 has occurred when calling these functions.
64 The following errors can occur:
66 Domain error: x is an infinity and y is not a NaN
68 errno is set to EDOM (but see BUGS). An invalid floating-point
69 exception (FE_INVALID) is raised.
70 These functions do not set errno for this case.
72 Domain error: y is zero
74 errno is set to EDOM. An invalid floating-point exception
75 (FE_INVALID) is raised.
76
78 For an explanation of the terms used in this section, see at‐
79 tributes(7).
80 ┌───────────────────────────┬───────────────┬─────────┐
82 │Interface │ Attribute │ Value │
83 ├───────────────────────────┼───────────────┼─────────┤
84 │drem(), dremf(), dreml(), │ Thread safety │ MT-Safe │
85 │remainder(), remainderf(), │ │ │
86 │remainderl() │ │ │
87 └───────────────────────────┴───────────────┴─────────┘
89 The functions remainder(), remainderf(), and remainderl() are specified
90 in C99, POSIX.1-2001, and POSIX.1-2008.
91 The function drem() is from 4.3BSD. The float and long double variants
93 dremf() and dreml() exist on some systems, such as Tru64 and glibc2.
94 Avoid the use of these functions in favor of remainder() etc.
95
97 Before glibc 2.15, the call
98 remainder(nan(""), 0);
100 returned a NaN, as expected, but wrongly caused a domain error. Since
102 glibc 2.15, a silent NaN (i.e., no domain error) is returned.
103 Before glibc 2.15, errno was not set to EDOM for the domain error that
105 occurs when x is an infinity and y is not a NaN.
106
108 The call "remainder(29.0, 3.0)" returns -1.
109
111 div(3), fmod(3), remquo(3)
112
114 This page is part of release 5.10 of the Linux man-pages project. A
115 description of the project, information about reporting bugs, and the
116 latest version of this page, can be found at
117 https://www.kernel.org/doc/man-pages/.
118 2020-06-09 REMAINDER(3)