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sqrt - Man Page

square root function


Math library (libm, -lm)


#include <math.h>

double sqrt(double x);
float sqrtf(float x);
long double sqrtl(long double x);

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


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.


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.


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

sqrt(), sqrtf(), sqrtl()Thread safetyMT-Safe


C11, POSIX.1-2008.


C99, POSIX.1-2001.

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

See Also

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

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), stress-ng(1), unu-1op(1).

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

2024-05-02 Linux man-pages 6.9.1