# SQRT

## NAME

sqrt, sqrtf, sqrtl − square root function

## SYNOPSIS

**#include <math.h>**

**double sqrt(double** *x***);**

float sqrtf(float *x***);**

long double sqrtl(long double *x***);**

Link with *−lm*.

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

**sqrtf**(), **sqrtl**():

_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L;

or *cc -std=c99*

## DESCRIPTION

The **sqrt**() function returns the nonnegative square root of *x*.

## RETURN VALUE

On success, these functions return the square root of *x*.

If *x* is a NaN, a NaN is returned.

If *x* is +0 (−0), +0 (−0) is returned.

If *x* is positive infinity, positive infinity is returned.

If *x* is less than −0, a domain error occurs, and a NaN 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:

Domain error: *x* less than −0

*errno* is set to **EDOM**. An invalid floating-point exception (**FE_INVALID**) is raised.

## CONFORMING TO

C99, POSIX.1-2001. The variant returning *double* also conforms to SVr4, 4.3BSD, C89.

## SEE ALSO

**cbrt(3)**, **csqrt(3)**, **hypot(3)**

## COLOPHON

This page is part of release 3.53 of the Linux *man-pages* project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man−pages/.