 Hyperbolastic functions

It seems like you might be referring to "hyperbolic functions." Hyperbolic functions are analogs of the ordinary trigonometric functions but for a hyperbola rather than a circle. The primary hyperbolic functions are: 1. **Hyperbolic Sine** (\(\sinh\)): \[ \sinh(x) = \frac{e^x - e^{-x}}{2} \] 2.