public static void YsAtX_Out_of_Range_Return_Empty_Arrays(double xCoord, double x, double y, double rotation)
        {
            CartesianCoordinate center = new CartesianCoordinate(x, y);
            EllipticalCurve     curve  = new EllipticalCurve(a, b, center, rotation, Tolerance);

            double[] yCoords = curve.YsAtX(xCoord);

            Assert.AreEqual(0, yCoords.Length);
        }
        public static void YsAtX(double xCoord, double x, double y, double rotation, double y1CoordExpected, double y2CoordExpected)
        {
            CartesianCoordinate center = new CartesianCoordinate(x, y);
            EllipticalCurve     curve  = new EllipticalCurve(a, b, center, rotation, Tolerance);

            double[] yCoords = curve.YsAtX(xCoord);

            Assert.AreEqual(y1CoordExpected, yCoords[0], Tolerance);
            Assert.AreEqual(y2CoordExpected, yCoords[1], Tolerance);
        }