Functional square root

The term "functional square root" generally refers to a concept in mathematics where one function is considered the square root of another function. More formally, if \( f(x) \) is a function, then a function \( g(x) \) can be considered a functional square root of \( f(x) \) if: \[ g(x)^2 = f(x) \] for all \( x \) in the domain of interest.