public static void Contour(double[,] zz, string options = "", bool labelContours = true)
        {
            if (!Hold)
            {
                PlotBuffer.Clear();
            }
            var p = new StoredPlot(zz, options, PlotTypes.ContourZZ);

            p.LabelContours = labelContours;
            PlotBuffer.Add(p);
            Plot(PlotBuffer);
        }
        public static void Contour(string filenameOrFunction, string options = "", bool labelContours = true)
        {
            if (!Hold)
            {
                PlotBuffer.Clear();
            }
            var p = new StoredPlot(filenameOrFunction, options, PlotTypes.ContourFileOrFunction);

            p.LabelContours = labelContours;
            PlotBuffer.Add(p);
            Plot(PlotBuffer);
        }