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.Dd May 7, 2026
.Dt SQRT 3
.Os
.Sh NAME
.Nm cbrt ,
.Nm cbrtf ,
.Nm cbrtl ,
.Nm rsqrt ,
.Nm rsqrtf ,
.Nm rsqrtl,
.Nm sqrt ,
.Nm sqrtf ,
.Nm sqrtl
.Nd cube root, square root, and inverse square root functions
.Sh LIBRARY
.Lb libm
.Sh SYNOPSIS
.In math.h
.Ft double
.Fn cbrt "double x"
.Ft float
.Fn cbrtf "float x"
.Ft long double
.Fn cbrtl "long double x"
.Ft double
.Fn rsqrt "double x"
.Ft float
.Fn rsqrtf "float x"
.Ft long double
.Fn rsqrtl "long double x"
.Ft double
.Fn sqrt "double x"
.Ft float
.Fn sqrtf "float x"
.Ft long double
.Fn sqrtl "long double x"
.Sh DESCRIPTION
The
.Fn cbrt ,
.Fn cbrtf ,
and
.Fn cbrtl
functions compute
the cube root of
.Fa x .
.Pp
The
.Fn rsqrt ,
.Fn rsqrtf ,
and
.Fn rsqrtl
functions compute
the inverse square root of
.Fa x .
.Pp
The
.Fn sqrt ,
.Fn sqrtf ,
and
.Fn sqrtl
functions compute the
non-negative square root of
.Fa x .
.Sh RETURN VALUES
The
.Fn cbrt ,
.Fn cbrtf ,
and
.Fn cbrtl
functions return the requested cube root.
.Pp
The
.Fn rsqrt ,
.Fn rsqrtf ,
and
.Fn rsqrtl
functions return 1 divided by the square root of
.Fa x
unless an error occurs.
An attempt to take the
.Fn rsqrt
of negative
.Fa x
raises an invalid exception and causes an \*(Na to be returned.
The inverse square root of \*(Pm0 returns \*(Pm\(if and
raises a divide-by-zero exception.
.Pp
The
.Fn sqrt ,
.Fn sqrtf ,
and
.Fn sqrtl
functions return the requested square root
unless an error occurs.
An attempt to take the
.Fn sqrt
of negative
.Fa x
raises an invalid exception and causes an \*(Na to be returned
(except that the square root of -0 is valid and equal to -0.)
.Sh SEE ALSO
.Xr fenv 3 ,
.Xr math 3
.Sh STANDARDS
The
.Fn cbrt ,
.Fn cbrtf ,
.Fn cbrtl ,
.Fn sqrt ,
.Fn sqrtf ,
and
.Fn sqrtl
functions conform to
.St -isoC-99 .
The
.Fn rsqrt ,
.Fn rsqrtf ,
and
.Fn rsqrtl
functions conform to ISO/IEC 9899:2024 ("ISO C23").
.\" .St -isoC-24 .
.Sh HISTORY
The
.Fn cbrt
function appeared in
.Bx 4.3 .
The
.Fn sqrt
function appeared in
.At v2 .
.Fn sqrtl
function appeared in
.Fx 8.0 .
The
.Fn cbrtl
function appeared in
.Fx 9.0 .
The
.Fn rsqrt ,
.Fn rsqrtf ,
and
.Fn rsqrtl
functions appeared in
.Fx 16.0 .