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

Defined in header <cmath>
float       cbrt ( float arg );
float       cbrtf( float arg );
(1) (since C++11)
double      cbrt ( double arg );
(2) (since C++11)
long double cbrt ( long double arg );
long double cbrtl( long double arg );
(3) (since C++11)
double      cbrt ( IntegralType arg );
(4) (since C++11)
1-3) Computes the cubic root of arg.
4) A set of overloads or a function template accepting an argument of any integral type. Equivalent to 2) (the argument is cast to double).


arg - value of a floating-point or Integral type

Return value

If no errors occur, the cubic root of arg (3arg), is returned.

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.


std::cbrt(arg) is not equivalent to std::pow(arg, 1.0/3) because std::pow cannot raise a negative base to a fractional exponent.


#include <iostream>
#include <cmath>
int main()
    // normal use
    std::cout << "cbrt(729) = " << std::cbrt(729) << '\n'
              << "cbrt(-0.125) = " << std::cbrt(-0.125) << '\n';
    // special values
    std::cout << "cbrt(-0) = " << std::cbrt(-0.0) << '\n'
              << "cbrt(+inf) = " << std::cbrt(INFINITY) << '\n';


cbrt(729) = 9
cbrt(-0.125) = -0.5
cbrt(-0) = -0
cbrt(+inf) = inf

See also

raises a number to the given power (xy)
computes square root (x)
computes square root of the sum of the squares of two given numbers (x2

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