# Function acosh Calculate the hyperbolic arccos of a value, defined as `acosh(x) = ln(sqrt(x^2 - 1) + x)`. For matrices, the function is evaluated element wise. ## Syntax ```js math.acosh(x) ``` ### Parameters Parameter | Type | Description --------- | ---- | ----------- `x` | number | Complex | Unit | Array | Matrix | Function input ### Returns Type | Description ---- | ----------- number | Complex | Array | Matrix | Hyperbolic arccosine of x ## Examples ```js math.acosh(1.5) // returns 0.9624236501192069 ``` ## See also [cosh](cosh.md), [asinh](asinh.md), [atanh](atanh.md)