---
name: "hypot"
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/hypot"
---

# hypot(3)

Euclidean distance function

## NAME

hypot, hypotf, hypotl - Euclidean distance function

## LIBRARY

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

## SYNOPSIS

```
#include <math.h>
```

**double hypot(double** *x***, double** *y***);** **float hypotf(float** *x***, float** *y***);** **long double hypotl(long double** *x***, long double** *y***);**

Feature Test Macro Requirements for glibc (see [**feature\_test\_macros**(7)](/feature_test_macros/7.md)):

**hypot**():

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

**hypotf**(), **hypotl**():

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

## DESCRIPTION

These functions return sqrt(*x*\**x*+*y*\**y*). This is the length of the hypotenuse of a right-angled triangle with sides of length *x* and *y*, or the distance of the point (*x*,*y*) from the origin.

The calculation is performed without undue overflow or underflow during the intermediate steps of the calculation.

## RETURN VALUE

On success, these functions return the length of the hypotenuse of a right-angled triangle with sides of length *x* and *y*.

If *x* or *y* is an infinity, positive infinity is returned.

If *x* or *y* is a NaN, and the other argument is not an infinity, a NaN is returned.

If the result overflows, a range error occurs, and the functions return **HUGE\_VAL**, **HUGE\_VALF**, or **HUGE\_VALL**, respectively.

If both arguments are subnormal, and the result is subnormal, a range error occurs, and the correct result is returned.

## ERRORS

See [**math\_error**(7)](/math_error/7.md) for information on how to determine whether an error has occurred when calling these functions.

The following errors can occur:

- Range error: result overflow

  *errno* is set to **ERANGE**. An overflow floating-point exception (**FE\_OVERFLOW**) is raised.

- Range error: result underflow

  An underflow floating-point exception (**FE\_UNDERFLOW**) is raised.

-

  These functions do not set *errno* for this case.

## ATTRIBUTES

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

| | | |
| --- | --- | --- |
| **Interface** | **Attribute** | **Value** |
| **hypot**(), **hypotf**(), **hypotl**() | Thread safety | MT-Safe |

## STANDARDS

C11, POSIX.1-2008.

## HISTORY

C99, POSIX.1-2001.

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

## SEE ALSO

[**cabs**(3)](/cabs/3.md), [**sqrt**(3)](/sqrt/3.md)