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

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

Syntax:

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

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

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

Below programs illustrate the acos() function in C++:

Example 1:-

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

Output:

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

Example 2:-

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

Output:

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

My Personal Notes arrow_drop_up Check out this Author's contributed articles.

If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.

Improved By : ManasChhabra2

Article Tags :
Practice Tags :

Be the First to upvote.

Please write to us at contribute@geeksforgeeks.org to report any issue with the above content.