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# tanh() function in C++ STL

The tanh() is an inbuilt function in C++ STL which returns the hyperbolic tangent of an angle given in radians.

Syntax :

`tanh(data_type x)`

Parameter :The function accepts one mandatory parameter x which specifies the hyperbolic angle in radian. The parameter can be of double, float or long double datatype.

Return Value:The function returns the hyperbolic tangent of the argument.

Below programs illustrate the above method:

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

Program 1:

## CPP

 `// CPP program to demonstrate the``// tanh() function``#include ``using` `namespace` `std;` `int` `main()``{``    ``double` `x = 4.1, result;` `    ``result = ``tanh``(x);``    ``cout << ``"tanh(4.1) = "` `<< result << endl;` `    ``// x in Degrees``    ``double` `xDegrees = 90;``    ``x = xDegrees * 3.14159 / 180;` `    ``result = ``tanh``(x);``    ``cout << ``"tanh(90 degrees) = "` `<< result << endl;` `    ``return` `0;``}`

Output

```tanh(4.1) = 0.999451
tanh(90 degrees) = 0.917152

```

Program 2:

## CPP

 `// CPP program to demonstrate the``// tanh() function``#include ``using` `namespace` `std;` `int` `main()``{``    ``int` `x = -4;``    ``double` `result;` `    ``result = ``tanh``(x);``    ``cout << ``"tanh(-4) = "` `<< result << endl;` `    ``// x in Degrees``    ``double` `xDegrees = 90;``    ``x = xDegrees * 3.14159 / 180;` `    ``result = ``tanh``(x);``    ``cout << ``"tanh(90 degrees) = "` `<< result << endl;` `    ``return` `0;``}`

Output

```tanh(-4) = -0.999329
tanh(90 degrees) = 0.761594

```

Errors and Exceptions: The function returns no matching function for call to error when a string or character is passed as an argument.

Program 3:

## CPP

 `// CPP program to demonstrate the tanh()``// function when a string is passed as argument``#include ``using` `namespace` `std;` `int` `main()``{``    ``string x = ``"gfg"``;``    ``double` `result;` `    ``result = ``tanh``(x);``    ``cout << ``"tanh(x) = "` `<< result << endl;` `    ``return` `0;``}`

Output:

`prog.cpp:14:20: error: no matching function for call to 'tanh(std::__cxx11::string&)'result = tanh(x);`