# Man Page

### Manual Section... (3) - page: remainder

## NAME

drem, dremf, dreml, remainder, remainderf, remainderl - floating-point remainder function## SYNOPSIS

Link with#include <math.h>/* The C99 versions */double remainder(doublex, doubley);float remainderf(floatx, floaty);long double remainderl(long doublex, long doubley);/* Obsolete synonyms */double drem(doublex, doubley);float dremf(floatx, floaty);long double dreml(long doublex, long doubley);

*-lm*.

Feature Test Macro Requirements for glibc (see
**feature_test_macros**(7)):

**remainder**():
_SVID_SOURCE || _BSD_SOURCE || _XOPEN_SOURCE >= 500 || _ISOC99_SOURCE; or
*cc -std=c99*

**remainderf**(),
**remainderl**():
_SVID_SOURCE || _BSD_SOURCE || _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE; or
*cc -std=c99*

**drem**(),
**dremf**(),
**dreml**():
_SVID_SOURCE || _BSD_SOURCE

## DESCRIPTION

The**remainder**() function computes 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 -
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.

## CONFORMING TO

The functions**remainder**(),

**remainderf**(), and

**remainderl**() are specified in C99 and POSIX.1-2001.

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

The call

remainder(nan(""), 0);

returns a NaN, as expected, but wrongly causes a domain error; it should yield a silent NaN.

## EXAMPLE

The call "remainder(29.0, 3.0)" returns -1.## SEE ALSO

**div**(3),

**fmod**(3),

**remquo**(3)

## COLOPHON

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## Index

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Time: 15:26:47 GMT, June 11, 2010