# Function atanh Calculate the hyperbolic arctangent of a value, defined as `atanh(x) = ln((1 + x)/(1 - x)) / 2`. For matrices, the function is evaluated element wise. ## Syntax ```js math.atanh(x) ``` ### Parameters Parameter | Type | Description --------- | ---- | ----------- `x` | number | Complex | Array | Matrix | Function input ### Returns Type | Description ---- | ----------- number | Complex | Array | Matrix | Hyperbolic arctangent of x ### Throws Type | Description ---- | ----------- ## Examples ```js math.atanh(0.5) // returns 0.5493061443340549 ``` ## See also [acosh](acosh.md), [asinh](asinh.md)