# atanh() function for complex number in C++

The atanh() function for complex number is defined in the complex header file. This function is the complex version of the atanh() function. This function is used to calculate the complex arc hyperbolic tangent of complex number z and returns the arc hyperbolic tangent of complex number z.

Syntax:

```template<class T> complex<T>
atanh (const complex<T>& z );```

Parameter: This method takes a mandatory parameter z which represents the complex number.

Return value: This function returns the arc hyperbolic tangent of complex number z.

Below programs illustrate the atanh() function in C++

Example 1:

## cpp

 `// c++ program to demonstrate` `// example of atanh() function.`   `#include ` `using` `namespace` `std;`   `// driver program` `int` `main()` `{` `    ``complex<``double``> complexnumber(2.0, 0.0);`   `    ``// use of atanh() function for complex number` `    ``cout << "The atanh of "` `         ``<< complexnumber` `         ``<< " is "` `         ``<< atanh(complexnumber)` `         ``<< endl;`   `    ``return` `0;` `}`

Output:

`The atanh of (2, 0) is (0.549306, 1.5708)`

Time Complexity: O(1)

Auxiliary Space: O(1)

Example 2:

## Cpp

 `// c++ program to demonstrate` `// example of atanh() function.`   `#include ` `using` `namespace` `std;`   `// driver program` `int` `main()` `{` `    ``complex<``double``> complexnumber(2.0, -0.0);`   `    ``// use of atanh() function for complex number` `    ``cout << "The atanh of "` `         ``<< complexnumber` `         ``<< " is "` `         ``<< atanh(complexnumber)` `         ``<< endl;`   `    ``return` `0;` `}`

Output:

`The atanh of (2, -0) is (0.549306, -1.5708)`

Time Complexity: O(1)

Auxiliary Space: O(1)

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