std::cbrt, std::cbrtf, std::cbrtl
Defined in header <cmath> |
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|---|---|---|
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 cube 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).
Parameters
| arg | - | value of a floating-point or Integral type |
Return value
If no errors occur, the cube root of arg (\(\small{\sqrt[3]{arg} }\)3√arg), 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.
Notes
std::cbrt(arg) is not equivalent to
std::pow(arg, 1.0/3) because the rational number \(\small{\frac1{3} }\)
1/3 is typically not equal to
1.0/3 and
std::pow cannot raise a negative base to a fractional exponent. Moreover,
std::cbrt(arg) usually gives more accurate results than
std::pow(arg, 1.0/3) (see example).
Example
#include <iostream>
#include <iomanip>
#include <cmath>
#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
See also
|
(C++11)(C++11)
|
raises a number to the given power (\(\small{x^y}\)xy) (function) |
|
(C++11)(C++11)
|
computes square root (\(\small{\sqrt{x} }\)√x) (function) |
|
(C++11)(C++11)(C++11)
|
computes square root of the sum of the squares of two or three (C++17) given numbers (\(\scriptsize{\sqrt{x^2+y^2} }\)√x2 +y2 ), (\(\scriptsize{\sqrt{x^2+y^2+z^2} }\)√x2 +y2 +z2 ) (function) |
C documentation for cbrt |
|
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