Coshc function

The `cosh` function, short for hyperbolic cosine, is a mathematical function denoted as \(\cosh(x)\). It is defined using the exponential function as follows: \[ \cosh(x) = \frac{e^x + e^{-x}}{2} \] where \(e\) is the base of the natural logarithm, approximately equal to 2.71828.