hypot, hypotf, hypotl — Euclidean distance function

## 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);```

`Link with -lm.`

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

hypot():

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

hypotf(), hypotl():

_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* Glibc versions <= 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 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) 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).

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

## Conforming to

C99, POSIX.1-2001, POSIX.1-2008.

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