# acosh() function with example in C++

C++ acosh() function: Here, we are going to learn about the acosh() function with example of cmath header in C++ programming language?
Submitted by IncludeHelp, on April 28, 2019

## C++ acosh() function

acosh() function is a library function of cmath header, it is used to find nonnegative area hyperbolic cosine of the given value, it accepts a number (x) and returns the nonnegative area hyperbolic cosine of x.

Note: Value of the x should not be less than the 1, if arguments are less than 0, it returns a domain error (-nan).

Syntax of acosh() function:

```    acosh(x);
```

Parameter(s): x – is the number/value whose nonnegative area hyperbolic cosine is calculated.

Return value: double – it returns double type value that is the nonnegative area hyperbolic cosine of the given number/value x.

Example:

```    Input:
float x = 2.45;

Function call:
acosh(x);

Output:
1.54471
```

### C++ code to demonstrate the example of acosh() function

```// C++ code to demonstrate the example of
// acosh() function

#include <iostream>
#include <cmath>
using namespace std;

// main() section
int main()
{
float x;

x = 1.0;
cout<<"acosh("<<x<<"): "<<acosh(x)<<endl;

x = 10.23;
cout<<"acosh("<<x<<"): "<<acosh(x)<<endl;

x = 2.45;
cout<<"acosh("<<x<<"): "<<acosh(x)<<endl;

return 0;
}
```

Output

```acosh(1): 0
acosh(10.23): 3.01607
acosh(2.45): 1.54471
```

Example with domain error

If we provide the value less than 1, it returns -nan.

```// C++ code to demonstrate the example of
// acosh() function

#include <iostream>
#include <cmath>
using namespace std;

// main() section
int main()
{
float x;

//no error with this input value
x = 1.0;
cout<<"acosh("<<x<<"): "<<acosh(x)<<endl;

//domain error with this input value
x = 0.25;
cout<<"acosh("<<x<<"): "<<acosh(x)<<endl;

return 0;
}
```

Output

```acosh(1): 0
acosh(0.25): -nan
```

Reference: C++ acosh() function