hypot(), hypotf(), hypotl()

Calculate the length of the hypotenuse for a right-angled triangle

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 );

Arguments:

x, y
The lengths of the sides that are adjacent to the right angle.

Library:

libm
The general-purpose math library.
libm-sve
(QNX Neutrino 7.1 or later) A library that optimizes the code for ARMv8.2 chips that have Scalable Vector Extension hardware.

Your system requirements will determine how you should work with these libraries:

Note: Compile your program with the -fno-builtin option to prevent the compiler from using a built-in version of the function.

Description:

These functions compute the length of the hypotenuse for a right triangle whose sides are x and y adjacent to the right angle. The calculation is equivalent to:

length = sqrt( x*x + y*y );

To check for error situations, use feclearexcept() and fetestexcept(). For example:

Returns:

The length of the hypotenuse.

If: These functions return: Errors:
The correct value would cause overflow Inf FE_OVERFLOW
x or y is ±Inf, and the other is any value including NaN Inf
x or y is NaN, and the other isn't ±Inf NaN
The correct result would cause underflow The correct result, after rounding FE_UNDERFLOW

These functions raise FE_INEXACT if the FPU reports that the result can't be exactly represented as a floating-point number.

Examples:

#include <stdio.h>
#include <math.h>
#include <fenv.h>
#include <stdlib.h>

int main( void )
{
    int except_flags;

    feclearexcept(FE_ALL_EXCEPT);

    printf( "%f\n", hypot( 3.0, 4.0 ) );

    except_flags = fetestexcept(FE_ALL_EXCEPT);
    if(except_flags) {
        /* An error occurred; handle it appropriately. */
    }

    return EXIT_SUCCESS;
}

produces the output:

5.000000

Classification:

C11, POSIX 1003.1

Safety:  
Cancellation point No
Interrupt handler Yes
Signal handler Yes
Thread Yes