---
name: "cabs"
section: "3"
platform: "linux"
package: "man-pages"
version: "6.19-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux", "freebsd"]
url: "https://new.carta.tech/cabs"
---

# cabs(3)

absolute value of a complex number

## NAME

cabs, cabsf, cabsl - absolute value of a complex number

## LIBRARY

Math library (*libm*, *-lm*)

## SYNOPSIS

```
#include <complex.h>
```

**double cabs(double complex** *z***);** **float cabsf(float complex** *z***);** **long double cabsl(long double complex** *z***);**

## DESCRIPTION

These functions return the absolute value of the complex number *z*. The result is a real number.

## ATTRIBUTES

For an explanation of the terms used in this section, see [**attributes**(7)](/attributes/7.md).

| | | |
| --- | --- | --- |
| **Interface** | **Attribute** | **Value** |
| **cabs**(), **cabsf**(), **cabsl**() | Thread safety | MT-Safe |

## STANDARDS

C11, POSIX.1-2008.

## HISTORY

glibc 2.1. C99, POSIX.1-2001.

## NOTES

The function is actually an alias for *hypot(a, b)* (or, equivalently, *sqrt(a\*a + b\*b)*).

## SEE ALSO

[**abs**(3)](/abs/3.md), [**cimag**(3)](/cimag/3.md), [**hypot**(3)](/hypot/3.md), [**complex**(7)](/complex/7.md)