public void RealRoots_TripleReal()
{
var a0 = 6d;
var a1 = -5d;
var a2 = -2d;
var roots = Cubic.RealRoots(a0, a1, a2);
Assert.That(roots.Item1, Is.EqualTo(3).Within(1e-14));
Assert.That(roots.Item2, Is.EqualTo(-2).Within(1e-14));
Assert.That(roots.Item3, Is.EqualTo(1).Within(1e-14));
}
public void RealRoots_DoubleReal1()
{
const double a0 = -2d;
const double a1 = 5d;
const double a2 = -4d;
var roots = Cubic.RealRoots(a0, a1, a2);
Assert.That(roots.Item1, Is.EqualTo(2).Within(1e-14));
Assert.That(roots.Item2, Is.EqualTo(1).Within(1e-14));
Assert.AreEqual(double.NaN, roots.Item3);
}
public void RealRoots_DoubleReal2()
{
var a0 = -4d;
var a1 = 8d;
var a2 = -5d;
var roots = Cubic.RealRoots(a0, a1, a2);
Assert.That(roots.Item1, Is.EqualTo(1).Within(1e-14));
Assert.That(roots.Item2, Is.EqualTo(2).Within(1e-14));
Assert.AreEqual(double.NaN, roots.Item3);
}
public void RealRoots_SingleReal()
{
var a0 = 1d;
var a1 = 5d;
var a2 = 2d;
var roots = Cubic.RealRoots(a0, a1, a2);
var root = roots.Item1;
var funcValue = root * (root * (root + a2) + a1) + a0;
Assert.That(funcValue, Is.EqualTo(0).Within(1e-14));
Assert.AreEqual(double.NaN, roots.Item2);
Assert.AreEqual(double.NaN, roots.Item3);
}
private static int GetLevel(double exp, ExpType type)
=> exp == 0 ? 1 : (int)Math.Ceiling(Cubic.RealRoots((type == ExpType.Level ? -2 : -20)
* exp / 75, 900 / 75, -125 / 75).Item1);