As of Version 7.0, is part of the built-in Mathematica kernel.
- To use , you first need to load the Regression Common Functions Package. You can do this by using or , which will automatically load the Regression Common Functions Package, or you can load the package directly by using .
- Possible settings for are Automatic, a list of numbers with the same length as the data, or a pure function.
- With the default setting Weights->Automatic, each data point is given a weight of 1.