hyperbolic function
n.
Any of a set of six functions related, for a real or complex variable x, to the hyperbola in a manner analogous to the relationship of the trigonometric functions to a circle, including:
■ The hyperbolic sine, defined by the equation sinh x = ¹/₂ (e^x - e-^x).
■ The hyperbolic cosine, defined by the equation cosh x = ¹/₂ (e^x + e-^x).
■ The hyperbolic tangent, defined by the equation tanh x = sinh x/cosh x.
■ The hyperbolic cotangent, defined by the equation coth x = cosh x/sinh x.
■ The hyperbolic secant, defined by the equation sech x = 1/cosh x.
■ The hyperbolic cosecant, defined by the equation csch x = 1/sinh x.

[TahlilGaran] American Dictionary ▲