std::cbrt, std::cbrtf, std::cbrtl

abs(int)labsllabsimaxabs (C++11)
abs(float)fabs
divldivlldivimaxdiv (C++11)

fmod
remainder (C++11)
remquo (C++11)
fma (C++11)
fmax (C++11)
fmin (C++11)
fdim (C++11)
nannanfnanl (C++11)(C++11)(C++11)

Exponential functions

exp
exp2 (C++11)
expm1 (C++11)

log
log10
log1p (C++11)
log2 (C++11)

Power functions

sqrt
cbrt (C++11)

hypot (C++11)
pow

Trigonometric and
hyperbolic functions

sin
cos
tan
asin
acos
atan
atan2

sinh
cosh
tanh
asinh (C++11)
acosh (C++11)
atanh (C++11)

Error and gamma functions

erf (C++11)
erfc (C++11)

lgamma (C++11)
tgamma (C++11)

Nearest integer floating point operations

ceil
floor
roundlroundllround (C++11)(C++11)(C++11)

trunc (C++11)
nearbyint (C++11)
rintlrintllrint (C++11)(C++11)(C++11)

Floating point manipulation functions

ldexp
scalbnscalbln (C++11)(C++11)
ilogb (C++11)
logb (C++11)

frexp
modf
nextafternexttoward (C++11)(C++11)
copysign (C++11)

Classification and comparison

fpclassify (C++11)
isfinite (C++11)
isinf (C++11)
isnan (C++11)
isnormal (C++11)
signbit (C++11)

isgreater (C++11)
isgreaterequal (C++11)
isless (C++11)
islessequal (C++11)
islessgreater (C++11)
isunordered (C++11)

Types

div_t
ldiv_t
lldiv_t (C++11)

imaxdiv_t (C++11)
float_t (C++11)
double_t (C++11)

Macro constants

HUGE_VALFHUGE_VALHUGE_VALL (C++11)(C++11)
math_errhandlingMATH_ERRNOMATH_ERREXCEPT (C++11)
INFINITY (C++11)
NAN (C++11)

Classification
FP_NORMALFP_SUBNORMALFP_ZEROFP_INFINITEFP_NAN (C++11) (C++11) (C++11) (C++11) (C++11)

Defined in header `<cmath>`
	(1)
float cbrt ( float num ) ; double cbrt ( double num ); long double cbrt ( long double num ) ;			(until C++23)
/floating-point-type/ cbrt ( /floating-point-type/ num ) ;			(since C++23) (constexpr since C++26)
float cbrtf( float num );		(2)	(since C++11) (constexpr since C++26)
long double cbrtl( long double num ) ;		(3)	(since C++11) (constexpr since C++26)
SIMD overload (since C++26)
Defined in header `<simd>`
template < /math-floating-point/ V > constexpr /deduced-simd-t/<V> cbrt ( const V& v_num ) ;		(S)	(since C++26)
Additional overloads (since C++11)
Defined in header `<cmath>`
template < class Integer > double cbrt ( Integer num ) ;		(A)	(constexpr since C++26)

1-3) Computes the cube root of num. The library provides overloads of std::cbrt for all cv-unqualified floating-point types as the type of the parameter. (since C++23)

S) The SIMD overload performs an element-wise std::cbrt on v_num.

(See math-floating-point and deduced-simd-t

(since C++26)

A) Additional overloads are provided for all integer types, which are treated as double.

(since C++11)

Parameters

num

-

floating-point or integer value

Return value

If no errors occur, the cube root of num ($\small{\sqrt[3]{num} }$ $3 \sqrt num$

If a range error occurs due to underflow, the correct result (after rounding) is returned.

Error handling

Errors are reported as specified in math_errhandling.

If the implementation supports IEEE floating-point arithmetic (IEC 60559),

if the argument is ±0 or ±∞, it is returned, unchanged.
if the argument is NaN, NaN is returned.

Notes

std::cbrt(num) is not equivalent to std::pow (num, 1.0 / 3 ) because the rational number

13

is typically not equal to 1.0 / 3 and std::pow cannot raise a negative base to a fractional exponent. Moreover, std::cbrt(num) usually gives more accurate results than std::pow (num, 1.0 / 3 ) (see example).

The additional overloads are not required to be provided exactly as (A). They only need to be sufficient to ensure that for their argument num of integer type, std::cbrt(num) has the same effect as std:: cbrt ( static_cast < double > (num) )

Example

Run this code

#include <cmath>
#include <iomanip>
#include <iostream>
#include <limits>
 
int main()
{
    std::cout
        << "Normal use:\n"
        << "cbrt(729)       = " << std::cbrt(729) << '\n'
        << "cbrt(-0.125)    = " << std::cbrt(-0.125) << '\n'
        << "Special values:\n"
        << "cbrt(-0)        = " << std::cbrt(-0.0) << '\n'
        << "cbrt(+inf)      = " << std::cbrt(INFINITY) << '\n'
        << "Accuracy and comparison with `pow`:\n"
        << std::setprecision(std::numeric_limits<double>::max_digits10)
        << "cbrt(343)       = " << std::cbrt(343) << '\n'
        << "pow(343,1.0/3)  = " << std::pow(343, 1.0 / 3) << '\n'
        << "cbrt(-343)      = " << std::cbrt(-343) << '\n'
        << "pow(-343,1.0/3) = " << std::pow(-343, 1.0 / 3) << '\n';
}

Possible output:

Normal use:
cbrt(729)       = 9
cbrt(-0.125)    = -0.5
Special values:
cbrt(-0)        = -0
cbrt(+inf)      = inf
Accuracy and comparison with `pow`:
cbrt(343)       = 7
pow(343,1.0/3)  = 6.9999999999999991
cbrt(-343)      = -7
pow(-343,1.0/3) = -nan

Compiler support
Freestanding and hosted
Language
Standard library
Standard library headers
Named requirements
Feature test macros (C++20)
Language support library
Concepts library (C++20)
Diagnostics library
Memory management library
Metaprogramming library (C++11)
General utilities library
Containers library
Iterators library
Ranges library (C++20)
Algorithms library
Strings library
Text processing library
Numerics library
Date and time library
Input/output library
Filesystem library (C++17)
Concurrency support library (C++11)
Execution support library (C++26)
Technical specifications
Symbols index
External libraries

powpowfpowl (C++11)(C++11)	raises a number to the given power (\(\small{x^y}\) $x y$ ) (function)
sqrtsqrtfsqrtl (C++11)(C++11)	computes square root (\(\small{\sqrt{x}}\) $\sqrt x$ ) (function)
hypothypotfhypotl (C++11)(C++11)(C++11)	computes hypotenuse \(\scriptsize{\sqrt{x^2+y^2}}\) $\sqrt x 2 +y 2$ and \(\scriptsize{\sqrt{x^2+y^2+z^2}}\) $\sqrt x 2 +y 2 +z 2$ (since C++17) (function)
C documentation for cbrt