drem, dremf, dreml, remainder, remainderf, remainderl - floating-point remainder function
Math library (libm
, -lm
)
#include <math.h>
double remainder(double x, double y);
float remainderf(float x, float y);
long double remainderl(long double x, long double y);
/* Obsolete synonyms */
[[deprecated]] double drem(double x, double y);
[[deprecated]] float dremf(float x, float y);
[[deprecated]] long double dreml(long double x, long double y);
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 <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
remainderf(), remainderl():
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
/* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* glibc <= 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.
The call "remainder(29.0, 3.0)" returns -1.
See math_error(7) for information on how to determine whether an error has occurred when calling these functions.
The following errors can occur:
x
is an infinity and y
is not a
NaNerrno
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.
y
is zeroerrno
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 |
C11, POSIX.1-2008.
None.
C99, POSIX.1-2001.
4.3BSD.
Tru64, glibc2.
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.