Lambert W function implementation in Java

I'm working on a project and have found myself in a situation where I need a function to be able to get at least an approximation of the value of W(x), the Lambert W function, where x can be any real number. I'm working in Java. I couldn't find any implementations of W in java when I searched. I am willing to code up the implementation myself if need be, but I am unsure of how that would be done right now. Any pushes in the right direction would be much appreciated.