{{keywords>wiki library source code example reference}}
===== tanh =====
<code cpp>
    double tanh(double);
</code>
Returns hyperbolic tangent of a radian angle x. 

===== cpp Sourcecode Example =====
<code cpp>
#include <iostream> /* including standard library */
#include <cmath> /* including math library */

using namespace std;
int main( void )
{
    double x;
    x = log(42);

    //cout.setf(ios::fixed, ios::floatfield);
    cout.precision(8);

    cout << "hyperbolic tangent of 42 is " << tanh (x) << endl;
    return 0;
}
</code>

==== output ====
   hyperbolic tangent of 42 is 0.99886686