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
42 integer. If the absolute value of x-n*y is 0.5, n is chosen to be
43 even.
44 These functions are unaffected by the current rounding mode (see
46 fenv(3)).
47 The drem() function does precisely the same thing.
49
51 On success, these functions return the floating-point remainder, x-n*y.
52 If the return value is 0, it has the sign of x.
53 If x or y is a NaN, a NaN is returned.
55 If x is an infinity, and y is not a NaN, a domain error occurs, and a
57 NaN is returned.
58 If y is zero, and x is not a NaN, a domain error occurs, and a NaN is
60 returned.
61
63 See math_error(7) for information on how to determine whether an error
64 has occurred when calling these functions.
65 The following errors can occur:
67 Domain error: x is an infinity and y is not a NaN
69 errno is set to EDOM (but see BUGS). An invalid floating-point
70 exception (FE_INVALID) is raised.
71 These functions do not set errno for this case.
73 Domain error: y is zero
75 errno is set to EDOM. An invalid floating-point exception
76 (FE_INVALID) is raised.
77
79 For an explanation of the terms used in this section, see
80 attributes(7).
81 ┌───────────────────────────┬───────────────┬─────────┐
83 │Interface │ Attribute │ Value │
84 ├───────────────────────────┼───────────────┼─────────┤
85 │drem(), dremf(), dreml(), │ Thread safety │ MT-Safe │
86 │remainder(), remainderf(), │ │ │
87 │remainderl() │ │ │
88 └───────────────────────────┴───────────────┴─────────┘
90 The functions remainder(), remainderf(), and remainderl() are specified
91 in C99, POSIX.1-2001, and POSIX.1-2008.
92 The function drem() is from 4.3BSD. The float and long double variants
94 dremf() and dreml() exist on some systems, such as Tru64 and glibc2.
95 Avoid the use of these functions in favor of remainder() etc.
96
98 Before glibc 2.15, the call
99 remainder(nan(""), 0);
101 returned a NaN, as expected, but wrongly caused a domain error. Since
103 glibc 2.15, a silent NaN (i.e., no domain error) is returned.
104 Before glibc 2.15, errno was not set to EDOM for the domain error that
106 occurs when x is an infinity and y is not a NaN.
107
109 The call "remainder(29.0, 3.0)" returns -1.
110
112 div(3), fmod(3), remquo(3)
113
115 This page is part of release 5.02 of the Linux man-pages project. A
116 description of the project, information about reporting bugs, and the
117 latest version of this page, can be found at
118 https://www.kernel.org/doc/man-pages/.
119 2017-09-15 REMAINDER(3)