drem, dremf, dreml, remainder, remainderf, remainderl - floating-point remainder
function
#include <math.h>
/* The C99 versions */
double remainder(double x, double y);
float remainderf(float x, float y);
long double remainderl(long double x, long double y);
/* Obsolete synonyms */
double drem(double x, double y);
float dremf(float x, float y);
long double dreml(long double x, long double y);
Link with
-lm.
Feature Test Macro Requirements for glibc (see
feature_test_macros(7)):
remainder():
_ISOC99_SOURCE ||
_POSIX_C_SOURCE >= 200112L
|| _XOPEN_SOURCE >= 500
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
remainderf(),
remainderl():
_ISOC99_SOURCE ||
_POSIX_C_SOURCE >= 200112L
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
drem(),
dremf(),
dreml():
/* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
These functions compute the remainder of dividing
x by
y. The
return value is
x-
n*
y, where
n is the value
x / y, rounded to the nearest integer. If the absolute
value of
x-
n*
y is 0.5,
n is chosen to be even.
These functions are unaffected by the current rounding mode (see
fenv(3)).
The
drem() function does precisely the same thing.
On success, these functions return the floating-point remainder,
x-
n*
y. If the return value is 0, it has the sign of
x.
If
x or
y is a NaN, a NaN is returned.
If
x is an infinity, and
y is not a NaN, a domain error occurs,
and a NaN is returned.
If
y is zero, and
x is not a NaN, a domain error occurs, and a NaN
is returned.
See
math_error(7) for information on how to determine whether an error
has occurred when calling these functions.
The following errors can occur:
- Domain error: x is an infinity and y is not a NaN
- errno is set to EDOM (but see BUGS). An invalid
floating-point exception (FE_INVALID) is raised.
- These functions do not set errno for this case.
- Domain error: y is zero
- errno is set to EDOM. An invalid floating-point exception
(FE_INVALID) is raised.
For an explanation of the terms used in this section, see
attributes(7).
| Interface |
Attribute |
Value |
| drem (), dremf (), dreml (), remainder (), remainderf (), remainderl
() |
Thread safety |
MT-Safe |
The functions
remainder(),
remainderf(), and
remainderl()
are specified in C99, POSIX.1-2001, and POSIX.1-2008.
The function
drem() is from 4.3BSD. The
float and
long
double variants
dremf() and
dreml() exist on some systems,
such as Tru64 and glibc2. Avoid the use of these functions in favor of
remainder() etc.
Before glibc 2.15, the call
remainder(nan(""), 0);
returned a NaN, as expected, but wrongly caused a domain error. Since glibc
2.15, a silent NaN (i.e., no domain error) is returned.
Before glibc 2.15,
errno was not set to
EDOM for the domain error
that occurs when
x is an infinity and
y is not a NaN.
The call "remainder(29.0, 3.0)" returns -1.
div(3),
fmod(3),
remquo(3)