template<class T> calculated-result-type acosh(const T x); template<class T, class Policy> calculated-result-type acosh(const T x, const Policy&);
Computes the reciprocal of (the restriction to the range of
cosine function, at x. Values returned are positive. Generalised
Taylor series are used near 1 and Laurent series are used near the infinity
to ensure accuracy.
If x is in the range
]-∞;+1[ then returns the result
The return type of this function is computed using the result
type calculation rules: the return type is
double when T is an integer type, and T
The final Policy argument is optional and can be used to control the behaviour of the function: how it handles errors, what level of precision to use etc. Refer to the policy documentation for more details.