...one of the most highly
regarded and expertly designed C++ library projects in the
world.

— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards

#include <boost/math/special_functions/cbrt.hpp>

namespace boost{ namespace math{ template <class T>calculated-result-typecbrt(T x); template <class T, class Policy>calculated-result-typecbrt(T x, const Policy&); }} // namespaces

Returns the cubed root of x: x^{1/3}.

The return type of this function is computed using the *result
type calculation rules*: the return is `double`

when *x* is an integer type and T otherwise.

The final Policy argument is optional and can be used to control the behaviour of the function: how it handles errors, what level of precision to use etc. Refer to the policy documentation for more details.

Implemented using Halley iteration.

For built in floating-point types `cbrt`

should have approximately 2 epsilon accuracy.

A mixture of spot test sanity checks, and random high precision test values calculated using NTL::RR at 1000-bit precision.