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)):

```
_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)

This page is part of release 4.15 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/.