public void TestBLtoXY()
        {
            {
                double B  = SurMath.DMStoRad(21.58470845);
                double L  = SurMath.DMStoRad(113.25314880);
                double L0 = SurMath.DMStoRad(111);

                //Ellipsoid ellipsoid = new Ellipsoid(6378245, 298.3);
                Ellipsoid ellipsoid = Ellipsoid.CreateBeijing1954();
                IProj     proj      = new GaussProj(ellipsoid);
                var       xy        = proj.BLtoXY(B, L, L0, 0, 0);

                Assert.AreEqual(2433586.692, xy.X, 0.001);
                Assert.AreEqual(250547.403, xy.Y, 0.001);
            }

            //数据来自《大地测量学基础》2版P193
            {
                double B  = SurMath.DMStoRad(17.33557339);
                double L  = SurMath.DMStoRad(119.15521159);
                double L0 = SurMath.DMStoRad(117);

                Ellipsoid ellipsoid = Ellipsoid.CreateBeijing1954();
                IProj     proj      = new GaussProj(ellipsoid);
                var       xy        = proj.BLtoXY(B, L, L0, 0, 0);

                Assert.AreEqual(1944359.6070, xy.X, 0.003);
                Assert.AreEqual(240455.4563, xy.Y, 0.001);
            }

            //数据来自《大地测量学基础》2版P193
            {
                double B  = SurMath.DMStoRad(17.33557339);
                double L  = SurMath.DMStoRad(119.15521159);
                double L0 = SurMath.DMStoRad(117);

                Ellipsoid ellipsoid = Ellipsoid.CreateXiAn1980();
                IProj     proj      = new GaussProj(ellipsoid);
                var       xy        = proj.BLtoXY(B, L, L0, 0, 0);

                Assert.AreEqual(1944325.8030, xy.X, 0.001);
                Assert.AreEqual(240451.5085, xy.Y, 0.001);
            }
        }
        public void TestXYtoBL()
        {
            {
                double x = 2433586.692, y = 250547.403;
                double L0 = SurMath.DMStoRad(111);

                Ellipsoid ellipsoid = Ellipsoid.CreateBeijing1954();
                IProj     proj      = new GaussProj(ellipsoid);
                //IProj proj = new UTMProj(ellipsoid);
                var BL = proj.XYtoBL(x, y, L0, 0, 0);

                Assert.AreEqual(21.58470845, SurMath.RadtoDMS(BL.B), 1e-8);
                Assert.AreEqual(113.25314880, SurMath.RadtoDMS(BL.L), 1e-8);

                x  = 3380330.773; y = 320089.9761;
                BL = proj.XYtoBL(x, y, L0, 0, 0);

                //此处的秒按常规处理会出现59.999996秒的问题
                Assert.AreEqual(30.30, SurMath.RadtoDMS(BL.B), 1e-7);
                Assert.AreEqual(114.20, SurMath.RadtoDMS(BL.L), 1e-7);
            }

            //数据来自《大地测量学基础》2版P194
            {
                double x = 1944359.6070, y = 240455.4563;
                double L0 = SurMath.DMStoRad(117);

                Ellipsoid ellipsoid = Ellipsoid.CreateBeijing1954();
                IProj     proj      = new GaussProj(ellipsoid);
                //IProj proj = new UTMProj(ellipsoid);
                var BL = proj.XYtoBL(x, y, L0, 0, 0);

                Assert.AreEqual(17.33557338, SurMath.RadtoDMS(BL.B), 1e-8);
                Assert.AreEqual(119.15521150, SurMath.RadtoDMS(BL.L), 1e-8);
            }
        }