LinearLeastSquares computes the least squares fit for the function f(x) = Β₀terms₀(x) + Β₁terms₁(x) + ..

LOESS computes the locally-weighted least squares polynomial regression to the data (xs[i], ys[i]).

PolynomialRegression performs a least squares regression with a polynomial of the given degree.

PolynomialRegressionResult is the resulting polynomial from a PolynomialRegression.