C++ Cube Root

C++ Cube Root

Ammar Ali Sep-11, 2022 C++ C++ Math
  1. Cube Root Using the cbrt() Function in C++
  2. Cube Root Using the pow() Function in C++

This tutorial will discuss computing the cube root of a number using the pow() or cbrt() function of the cmath library in C++.

Cube Root Using the cbrt() Function in C++

We can find the cube root of a number using the cbrt() function of the cmath library of C++. The basic syntax of the function is given below.

output = cbrt(input);

The input of the cbrt() function should be several data type int, float, double, or long. The input should not be a string or character value.

The cbrt() function returns the cube root of the input number in the double data type, but we can also store the result in other data types like float or long.

For example, let’s take the cube root of a number using the cbrt() function. See the code below.

#include <iostream>
#include <cmath>

int main() {
    double number = 3;
    double cubeRoot = std::cbrt(number);
    std::cout << cubeRoot;

    return 0;
}

Output:

1.44225

We have included two libraries, iostream and cmath, in the above code. The cout function in the above code belongs to the iostream library, which displays the output.

The cbrt() function belongs to the cmath library and is used to take the cube root of the given number. We have used the double data type to store the given number and the output of the cbrt function.

The cbrt() function returns the result in double data type but we can also use the cbrtf() and cbrtl() function to take the cube root of a number. The cbrtf() function returns the result in floating point data type and the cbrtl() function returns the data type in long data type.

The difference between these functions is the size of the output result. For example, the size of a float variable is 4 bytes, and the size of a double and long variable is 8 bytes.

So, a long or double variable will take more space in the memory than the float variable, but it can be used to take the cube root of very long numbers so that the result will be accurate.

Cube Root Using the pow() Function in C++

We can find the cube root of a number using the pow() function of the cmath library of C++. The pow() function takes the power of a given number.

We know that the cube root can be expressed as an exponent with the value 1/3, and to take the cube root of a number, we have to pass the 1/3 exponent as the power inside the pow() function. The basic syntax of the function is given below.

output = pow(input, power);

The input number and the power of the pow() function should be several data types float, double, or long. The input and the power should not be a string or character value.

The pow() function returns the result in the same data type as the input number and power. For example, let’s take the cube root of a number using the pow() function.

See the code below.

#include <iostream>
#include <cmath>

int main() {
    double number = 3;
    double power = 1/3.;
    double cubeRoot = std::pow(number, power);
    std::cout << cubeRoot;

    return 0;
}

Output:

1.44225

The result of the pow() function is the same as compared with the cbrt() function. The power function will not work if an input number is negative and will give unexpected results.

The pow() function will give an error if the number and the power are zero, and it will also give an error if the result is too large or too small.

Author: Ammar Ali
Ammar Ali avatar Ammar Ali avatar

Hello! I am Ammar Ali, a programmer here to learn from experience, people, and docs, and create interesting and useful programming content. I mostly create content about Python, Matlab, and Microcontrollers like Arduino and PIC.

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