# FMOD(3) - Linux man page online | Library functions

Floating-point remainder function.

Chapter

2017-09-15

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

## 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). ┌─────────────────────────┬───────────────┬─────────┐ │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)## COLOPHON

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/.**2017-09-15 FMOD(3)**

This manual | Reference | Other manuals |
---|---|---|

fmod(3) | referred by | remainder(3) | remquo(3) |

refer to | attributes(7) | feature_test_macros(7) | math_error(7) | remainder(3) |