protected BigRational _2df_get_br_ordinate_start()
        {
            BigRational br_top_edge        = BigRational.ConvertToBigRational(_2df_top_edge);
            BigRational br_interval_length = BigRational.Divide(BigRational.ConvertToBigRational(_2df_bottom_edge) - br_top_edge, new BigRational(_2df_imagine_height));

            return(br_top_edge + br_interval_length * (new BigRational(_2df_imagine_top)));
        }
        protected BigRational _2df_get_br_abciss_start()
        {
            BigRational br_left_edge       = BigRational.ConvertToBigRational(_2df_left_edge);
            BigRational br_interval_length = BigRational.Divide(BigRational.ConvertToBigRational(_2df_right_edge) - br_left_edge, new BigRational(_2df_imagine_width));

            return(br_left_edge + br_interval_length * (new BigRational(_2df_imagine_left)));
        }
 protected BigRational _2df_get_br_ordinate_interval_length()
 {
     return(BigRational.Divide(BigRational.ConvertToBigRational(_2df_bottom_edge) - BigRational.ConvertToBigRational(_2df_top_edge), new BigRational(_2df_imagine_height)));
 }
 protected BigRational _2df_get_br_abciss_interval_length()
 {
     return(BigRational.Divide(BigRational.ConvertToBigRational(_2df_right_edge) - BigRational.ConvertToBigRational(_2df_left_edge), new BigRational(_2df_imagine_width)));
 }