man pages section 3: Extended Library Functions

## hypotl(3M)

#### Name

hypot, hypotf, hypotl– Euclidean distance function

#### Synopsis

```c99 [ flag... ] file... -lm [ library... ]
#include <math.h>

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

#### Description

These functions compute the length of the square root of x2 + y2 without undue overflow or underflow.

#### Return Values

Upon successful completion, these functions return the length of the hypotenuse of a right angled triangle with sides of length x2 and y2.

If the correct value would cause overflow, a range error occurs and hypot(), hypotf(), and hypotl() return the value of the macro HUGE_VAL, HUGE_VALF, and HUGE_VALL, respectively.

If x or y is ±Inf, +Inf is returned even if one of x or y is NaN.

If x or y is NaN and the other is not ±Inf, a NaN is returned.

#### Errors

These functions will fail if:

Range Error

The result overflows.

If the integer expression (math_errhandling & MATH_ERREXCEPT) is non-zero, the overflow floating-point exception is raised.

#### Usage

hypot(x,y), hypot(y,x), and hypot(x, -y) are equivalent.

hypot(x, ±0) is equivalent to fabs(x).

These functions takes precautions against underflow and overflow during intermediate steps of the computation.

An application wanting to check for exceptions should call feclearexcept(FE_ALL_EXCEPT) before calling these functions. On return, if fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an exception has been raised. An application should either examine the return value or check the floating point exception flags to detect exceptions.

#### Attributes

See attributes(5) for descriptions of the following attributes:

ATTRIBUTE TYPE

ATTRIBUTE VALUE

Interface Stability

Standard

MT-Level

MT-Safe