sqrt(), sqrtf(), sqrtl()

Calculate the nonnegative square root of a number

Synopsis:

#include <math.h>

double sqrt( double x );

float sqrtf( float x );

long double sqrtl( long double x );

Arguments:

x
The number that you want to calculate the square root of.

Library:

libm

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

Description:

These functions compute the nonnegative square root of x.

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

Returns:

The nonnegative square root of the given number. For finite values of x < -0, a domain error occurs, and these functions return NaN. The return value when x is -Inf is NaN, and a domain error occurs. If x is NaN, NaN is returned. If x is ±0 or +Inf, x is returned.

Errors:

FE_INVALID
The x argument is less than 0, or is -Inf.

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", sqrt(.5) );

    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:

0.707107

Classification:

ANSI, POSIX 1003.1

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