private double brentMethod()
{
double guessVal = (Mathd.Sqrt(obj.parent.gravParam) * currentTime) / semiMajorAxis;
//second two params are the min and max values the solver will search for, they are at this point total spitballing
Accord.Math.Optimization.BrentSearch searcher = new Accord.Math.Optimization.BrentSearch(substitutionFunction, -2.0d * (guessVal + 20.0d), 2.0d * (guessVal + 20.0d));
searcher.Tolerance = 0.0001;
searcher.FindRoot();
return(searcher.Solution);
}
public void ConstructorTest()
{
// Suppose we were given the function x³ + 2x² - 10x and
// we have to find its root, maximum and minimum inside
// the interval [-4,3]. First, we express this function
// as a lambda expression:
Func<double, double> function = x => x * x * x + 2 * x * x - 10 * x;
// And now we can create the search algorithm:
BrentSearch search = new BrentSearch(function, -4, 3);
// Finally, we can query the information we need
double max = search.Maximize(); // occurs at -2.61
double min = search.Minimize(); // occurs at 1.27
double root = search.FindRoot(); // occurs at 0.50
Assert.AreEqual(-2.6103173042172645, max);
Assert.AreEqual(1.2769840667540548, min);
Assert.AreEqual(-0.5, root);
}
/// <summary>
/// Should solve
/// </summary>
/// <param name="c"></param>
/// <param name="t0"></param>
/// <param name="distance"></param>
/// <returns></returns>
public static double PointAtDistanceFrom(this ICurve c, double t0, double distance)
{
Func<double, double> objFunc = t1 =>
{
var length3 = t0 < t1 ? c.GetLength3(t0, t1) : c.GetLength3(t1, t0);
return length3 - Math.Abs(distance);
};
var domain = c.Domain();
var min = distance < 0.0 ? 0.8*domain[0] : t0;
var max = distance < 0.0 ? t0 : 1.2*domain[1];
var solver = new BrentSearch(objFunc, min, max);
solver.FindRoot();
var sol = solver.Solution;
return sol;
}