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

• Last Updated : 17 Aug, 2022

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

Syntax:

```template<class T> complex<T>
acosh (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 cosine of complex number z. Below programs illustrate the acosh() function in C++:

Example 1:

## cpp

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

Output:

`The acosh of (-2,0) is (1.31696,3.14159)`

Time Complexity: O(1)
Auxiliary Space: O(1)

Example 2:

## cpp

 `// c++ program to demonstrate``// example of acosh() function.` `#include& lt; bits / stdc++.h & gt;` `using` `namespace` `std;` `// driver program``int` `main()``{``    ``complex& lt;``    ``double``& gt;``    ``complexnumber(0.5, 0.0);` `    ``// use of acosh() function for complex number``    ``cout& lt;``    ``<``    ``"``    ``The acosh of& quot;``    ``<``    ``<``    ``complexnumber& lt;``    ``<``    ``"``    ``is& quot;``    ``<``    ``<``    ``acosh(complexnumber) & lt;``    ``<``    ``endl;` `    ``return` `0;``}`

Output:

`The acosh of (0.5,0) is (0,1.0472)`

Time Complexity: O(1)
Auxiliary Space: O(1)

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