Understanding Hyperbolic Tangent
The hyperbolic tangent function, tanh(x), is one of the six hyperbolic functions. It is defined as the ratio of the hyperbolic sine to the hyperbolic cosine: tanh(x) = sinh(x)/cosh(x). Using exponential notation, tanh(x) = (ex - e-x) / (ex + e-x).
Key Properties
Definition
The ratio of hyperbolic sine to hyperbolic cosine.
tanh(x) = sinh(x) / cosh(x)
Exponential Form
Expressed using Euler's number e.
(e^x - e^-x) / (e^x + e^-x)
Range
The output is always between -1 and 1 (exclusive), approaching these as asymptotes.
Range: (-1, 1)
Odd Function
tanh(-x) = -tanh(x). The function is symmetric about the origin.
tanh(-x) = -tanh(x)
Derivative
The derivative of tanh(x) is sech squared of x.
d/dx tanh(x) = sech^2(x)
Identity
An important identity relating tanh and sech.
1 - tanh^2(x) = sech^2(x)
Applications of tanh
- Activation function in neural networks and deep learning
- Modeling catenary curves and hanging chains
- Special relativity (rapidity)
- Fluid dynamics and boundary layer theory
- Signal processing and control theory