public static string GetOxyPlotSvg <G, M, RF>(this IDensity <G, M, RF> d, string title)
            where G :
        IBaseStructure <M>,
        IRealEmbedding <M, RF>
            where M :
        struct
            where RF :
        struct
        {
            var oxyplot     = d.OxyPlot(title);
            var svgExporter = new SvgExporter {
                Width = 600, Height = 400
            };
            var res = svgExporter.ExportToString(oxyplot);

            return(res);
        }
        public static void SaveOxyPlotPdf <G, M, RF>(this IDensity <G, M, RF> d, string filename = null)
            where G :
        IBaseStructure <M>,
        IRealEmbedding <M, RF>
            where M :
        struct
            where RF :
        struct
        {
            filename = filename ?? d.GetTrimmedName() + ".pdf";
            var oxyplot = d.OxyPlot(Path.GetFileName(filename));

            using (var stream = File.Create(filename))
            {
                var pdfExporter = new PdfExporter {
                    Width = 600, Height = 400
                };
                pdfExporter.Export(oxyplot, stream);
            }
        }