dichotomy

using System;

public class DichotomyMethod
{
    public readonly double Accuracy;
    public readonly double Step;

    public DichotomyMethod(double accuracy = 0.01, double step = 0.001)
    {
        if (accuracy <= 0)
            throw new Exception("Wrong accuracy");

        if (step <= 0)
            throw new Exception("Wrong step");

        Accuracy = accuracy;
        Step = step;
    }

    public (double, double) FindRoot(Func<double, double> func, double start, double end)
    {
        if (start > end)
            throw new Exception("Wrong interval");
        if (2 * Step >= Accuracy)
            throw new Exception("Wrong step && accuracy");

        var len = 1d;
        int counter = 0;
        double initialStart = start, initialEnd = end;
        for (var i = 1; len > Accuracy; ++i)
        {
            var x1 = (start + end) / 2 - Step;
            var x2 = (start + end) / 2 + Step;

            if (func(x1) < func(x2))
            {
                end = x2;
            }
            else
            {
                start = x1;
            }

            len = (initialEnd - initialStart - 2 * Step) / Math.Pow(2, i - 1) + 2 * Step;
            counter++;
        }

        Console.WriteLine($"Number of iterations for the DichotomyMethod {counter} ");
        return (start, end);
    }
}