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

Use the -l m option to qcc to link against this library.

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():

Returns:

The length of the hypotenuse.

If the correct value would cause an overflow, a range error occurs, and these functions return 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, the functions return NaN.

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

Errors:

FE_OVERFLOW
The result is too large to be representable.
FE_UNDERFLOW
The result is subnormal with a loss of precision.

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_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW);
    if(except_flags) {
        /* An error occurred; handle it appropriately. */
    }

    return EXIT_SUCCESS;
}

produces the output:

5.000000

Classification:

ANSI, POSIX 1003.1

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