# sqrt - Man Page

square root function

## Synopsis

#include <math.h> double sqrt(doublex); float sqrtf(floatx); long double sqrtl(long doublex);

`Link with `

*-lm*.

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

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

_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L || /* Since glibc 2.19: */ _DEFAULT_SOURCE || /* Glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

## Description

These functions return 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.

## Attributes

For an explanation of the terms used in this section, see attributes(7).

Interface | Attribute | Value |
---|---|---|

sqrt(), sqrtf(), sqrtl() | Thread safety | MT-Safe |

## Conforming to

C99, POSIX.1-2001, POSIX.1-2008.

The variant returning *double* also conforms to SVr4, 4.3BSD, C89.

## See Also

## Colophon

This page is part of release 5.11 of the Linux *man-pages* project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.

## Referenced By

cbrt(3), exp(3), exp10(3), exp2(3), ffmpeg-all(1), ffmpeg-filters(1), ffplay-all(1), ffprobe-all(1), glutSolidDodecahedron(3), glutWireDodecahedron(3), gmx-editconf(1), hypot(3), log(3), log10(3), log2(3), pow(3).

The man pages sqrtf(3) and sqrtl(3) are aliases of sqrt(3).