SQRT(3) | Linux Programmer's Manual | SQRT(3) |

# NAME

sqrt, sqrtf, sqrtl - 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

cbrt(3), csqrt(3), hypot(3)# COLOPHON

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2021-03-22 |