public void TestHypotWithSomeKnownValues()
{
Assert.AreEqual(13.0, DoubleArithmetic.Hypotenuse(5.0, 12.0));
Assert.AreEqual(25.0, DoubleArithmetic.Hypotenuse(7.0, 24.0));
Assert.AreEqual(641.0, DoubleArithmetic.Hypotenuse(200.0, 609.0));
Assert.AreEqual(661.0, DoubleArithmetic.Hypotenuse(300.0, 589.0));
}
public void TestThatNaiveHypotFailsWhenHypotWorks()
{
// test with large values
const double m = 1e308;
var x = 0.3 * m;
var y = 0.4 * m;
var naive = Math.Sqrt(x * x + y * y);
var hypot = DoubleArithmetic.Hypotenuse(x, y);
// assert that naive method blows up
Assert.IsTrue(double.IsInfinity(naive));
// assert that our method gives the correct answer
Assert.AreEqual(0.5 * m, hypot);
// test with small values
const double eps = 1e-324;
x = 3 * eps;
y = 4 * eps;
naive = Math.Sqrt(x * x + y * y);
hypot = DoubleArithmetic.Hypotenuse(x, y);
// assert that naive method vanishes
Assert.AreEqual(naive, 0);
// assert that our method gives the correct answer
Assert.AreEqual(5 * eps, hypot);
}
public void TestHypot3D()
{
var hypot = DoubleArithmetic.Hypotenuse(3, 4, 12);
Assert.AreEqual(13.0, hypot);
}