REMAINDER
Section: Linux Programmer's Manual (3)
Updated: 2017-09-15
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NAME
drem, dremf, dreml, remainder, remainderf, remainderl - floating-point remainder function
SYNOPSIS
#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
DESCRIPTION
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.
RETURN VALUE
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.
ERRORS
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 zeroerrno
-
is set to
EDOM.
An invalid floating-point exception
(FE_INVALID)
is raised.
ATTRIBUTES
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
|
CONFORMING TO
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.
BUGS
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.
errno was not set
EXAMPLE
The call "remainder(29.0, 3.0)" returns -1.
SEE ALSO
div(3),
fmod(3),
remquo(3)
COLOPHON
This page is part of release 4.13 of the Linux
man-pages
project.
A description of the project,
information about reporting bugs,
and the latest version of this page,
can be found at
https://www.kernel.org/doc/man-pages/.
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- ERRORS
-
- ATTRIBUTES
-
- CONFORMING TO
-
- BUGS
-
- EXAMPLE
-
- SEE ALSO
-
- COLOPHON
-
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- Running on 
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