public void TestSqrt()
        {
            var z = new Complex(1.961570561, 0.3901806440);
            var w = ComplexArithmetic.Sqrt(z);

            Assert.IsTrue(z.ApproximatelyEquals(w * w, Epsilon));

            z = new Complex(-1.961570561, 0.3901806440);
            w = ComplexArithmetic.Sqrt(z);

            Assert.IsTrue(z.ApproximatelyEquals(w * w, Epsilon));

            z = new Complex(-1.961570561, -0.3901806440);
            w = ComplexArithmetic.Sqrt(z);

            Assert.IsTrue(z.ApproximatelyEquals(w * w, Epsilon));

            z = new Complex(1.961570561, -0.3901806440);
            w = ComplexArithmetic.Sqrt(z);

            Assert.IsTrue(z.ApproximatelyEquals(w * w, Epsilon));
        }