# fmodf (3)

# NAME

fmod, fmodf, fmodl - floating-point remainder function# SYNOPSIS

#include <math.h>

Link withdouble fmod(doublex, doubley);float fmodf(floatx, floaty);long double fmodl(long doublex, long doubley);

*-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

|| /* 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).

Interface | Attribute | Value |

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

# 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)