FMOD(3) | Library Functions Manual | FMOD(3)

# NAME

`fmod`, `fmodf`, `fmodl` — floating-point remainder functions

# SYNOPSIS

Math Library (libm, -lm)
`#include <math.h>`

double
`fmod`(double x, double y);

float
`fmodf`(float x, float y);

long double
`fmodl`(long double x, long double y);

# DESCRIPTION

The `fmod`() function computes the floating-point remainder of x/y. The `fmodf`() function is a single precision version of `fmod`(). The `fmodl`() function is an extended precision version of `fmod`().

# RETURN VALUES

The `fmod`(), `fmodf`() and `fmodl`() functions return the value x-i*y, for some integer i such that, if y is non-zero, the result has the same sign as x and magnitude less than the magnitude of y. If y is zero, whether a domain error occurs or the `fmod`() function returns zero is implementation-defined.

# SEE ALSO

remainder(3)

# STANDARDS

The `fmod`() function conforms to ANSI X3.159-1989 (“ANSI C89”).

# HISTORY

An `fmod`() function first appeared in Version 5 AT&T UNIX.

June 7, 2025 | Debian