Returns the hyperbolic tangent of its argument.

    Format

      #include  <math.h>

      double tanh  (double x);

      float tanhf  (float x); (Integrity servers, Alpha)

      long double tanhl  (long double x); (Integrity servers, Alpha)

1 - Argument

 x

    A real number.

2 - Description

    The tanh functions return the hyperbolic tangent their argument,
    calculated as (e**x - e**(-x))/(e**x + e**(-x)).

3 - Return Values

    n                  The hyperbolic tangent of the argument.
    HUGE_VAL           The argument is too large; errno is set to
                       ERANGE.
    NaN                x is NaN; errno is set to EDOM.
    0                  Underflow occurred; errno is set to ERANGE.