FABS(3) | Library Functions Manual | FABS(3)

# NAME

`fabs`, `fabsf`, `fabsl` — floating-point absolute value functions

# SYNOPSIS

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

double
`fabs`(double x);

float
`fabsf`(float x);

long double
`fabsl`(long double x);

# DESCRIPTION

The `fabs`() function computes the absolute value of a floating-point number x. The `fabsf`() function is a single precision version of `fabs`(). The `fabsl`() function is an extended precision version of `fabs`().

# RETURN VALUES

The `fabs`(), `fabsf`() and `fabsl`() functions return the absolute value of x.

# SEE ALSO

abs(3), ceil(3), floor(3), rint(3)

# STANDARDS

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

# HISTORY

An `fabs`() function first appeared in Version 6 AT&T UNIX.

June 6, 2025 | Debian