fmod, fmodf, fmodl - floating-point remainder function

**#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

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.

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.

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.

For an explanation of the terms used in this section, see

**attributes**(7).

Interface |
Attribute |
Value |

fmod (), fmodf (), fmodl () |
Thread safety |
MT-Safe |

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

The variant returning

*double* also conforms to SVr4, 4.3BSD, C89.

Before version 2.10, the glibc implementation did not set

*errno* to

**EDOM** when a domain error occurred for an infinite

*x*.

**remainder**(3)