fabsl(3)

fabsl3

Absolute value of floating-point number

Part of fabs(3).

Usage

#include <math.h>

double fabs(double x); float fabsf(float x); long double fabsl(long double x);

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

fabsf(), fabsl():

    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

Library

Math library (libm, -lm)

Overview

These functions return the absolute value of the floating-point number x.

Return value

These functions return the absolute value of x.

If x is a NaN, a NaN is returned.

If x is -0, +0 is returned.

If x is negative infinity or positive infinity, positive infinity is returned.

Errors

No errors occur.

Attributes

For an explanation of the terms used in this section, see attributes(7).

InterfaceAttributeValue
fabs(), fabsf(), fabsl()Thread safetyMT-Safe

Releases

13 releases since Debian 3.0 (Woody); the text changed 12 times.

  1. 3.0
  2. 3.1
  3. 4.0
  4. 5.0
  5. 6.0
  6. 7
  7. 8
  8. 9
  9. 10
  10. 11
  11. 12
  12. 13
  13. Arch

Standards

C11, POSIX.1-2008.

History

C99, POSIX.1-2001.

The variant returning double also conforms to SVr4, 4.3BSD, C89.

From man-pages 6.19-1 in Arch Linux 2026-11-01. Parsed by carta from the page's man source.