# FMOD

NAME

SYNOPSIS

DESCRIPTION

RETURN VALUE

ERRORS

ATTRIBUTES

CONFORMING TO

BUGS

SEE ALSO

COLOPHON

## NAME

fmod, fmodf,
fmodl - floating-point remainder function

## SYNOPSIS

**#include
<math.h>**

**double
fmod(double** *x***, double** *y***); **

float fmodf(float *x***, float** *y***);
**

long double fmodl(long double *x***, long
double** *y***);**

Link with
*-lm*.

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

**fmodf**(),
**fmodl**():

_ISOC99_SOURCE ||
_POSIX_C_SOURCE >= 200112L

|| /* Since glibc 2.19: */ _DEFAULT_SOURCE

|| /* Glibc versions <= 2.19: */ _BSD_SOURCE ||
_SVID_SOURCE

## DESCRIPTION

These functions
compute the floating-point remainder of dividing *x* by
*y*. The return value is *x* - *n* *
*y*, where *n* is the quotient of *x* /
*y*, rounded toward zero to an integer.

## RETURN VALUE

On success,
these functions return the value
*x *- *n***y*, for some integer
*n*, such that the returned value has the same sign as
*x* and a magnitude less than the magnitude of
*y*.

If *x* or
*y* is a NaN, a NaN is returned.

If *x* is
an infinity, a domain error occurs, and a NaN is
returned.

If *y* is
zero, a domain error occurs, and a NaN is returned.

If *x* is
+0 (-0), and *y* is not zero, +0 (-0) 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

*errno* is set to
**EDOM** (but see BUGS). An invalid floating-point
exception (**FE_INVALID**) is raised.

Domain error: *y* is
zero

*errno* 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).

## CONFORMING TO

C99,
POSIX.1-2001, POSIX.1-2008.

The variant
returning *double* also conforms to SVr4, 4.3BSD,
C89.

## BUGS

Before version
2.10, the glibc implementation did not set *errno* to
**EDOM** when a domain error occurred for an infinite
*x*.

## SEE ALSO

**remainder**(3)

## COLOPHON

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