## Hyperbolic Cosine

(cosh)

Calcute implements the **hyperbolic cosine** function with the *cosh* function.

cosh(1)
1.54308063482

It is defined in terms of the exponential function as cosh(x) = (exp(x) + exp(-x)) / 2.

A similarity exists between the trigonometric cosine and the hyperbolic cosine functions. While the former is best described graphically using a unit circle with equation (x^{2} + y^{2}) = 1, the hyperbolic cosine follows the unit hyperbola with equation (x^{2} - y^{2}) = 1 instead.