A function composed by summing powers of its variables. In the spatial context, where x coordinates and y coordinates are the variables, a polynomial has terms like 1, x, x 2 , y, y 2 , xy, x 2 y, and so on, all of which are added together with coefficients, b 0 + b 1 x + b 2 y + ...
Note: In a spatial scale, polynomial is visualized as a polyline , or a polynomial curve.