## table of contents

FMOD(3) | Linux Programmer's Manual | FMOD(3) |

# NAME¶

fmod, fmodf, fmodl - floating-point remainder function

# SYNOPSIS¶

#include <math.h>

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

Link with *-lm*.

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

|| /* 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¶

# COLOPHON¶

This page is part of release 5.10 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/.

2017-09-15 |