Contour plots can be made using either matrix data or xyz triplets. Contours of matrix data can be plotted using non-linear user-supplied spacing. Either type of contour data can be plotted on linear or log axes. Each contour level can have its own color, thickness and line style. Labels can be a mixture of automatic and manual. Automatic recalculation can be turned off. Zoom and resize are instantaneous. XYZ contours create Delauny triangulations and support smooth interpolation.