public double FindRoot(Func <double, double> function, Func <double, double> derivative, double a, double b, double eps1, double eps2, ref int numOfIterations)
{
var bisectA = a;
var bisectB = b;
var bisectionresult = new Bisection().FindRoot(ref bisectA, ref bisectB, eps1, function, ref numOfIterations);
Console.WriteLine("Interval after bisection: [{0};{1}]", bisectA, bisectB);
double xPrev = (bisectA + bisectB) / 2;
Console.Write("{0} ", xPrev);
double x = 0;
int i;
for (i = 0; i < 100; i++) //prevent infinite loop
{
x = xPrev - function(xPrev) / derivative(xPrev);
Console.Write("{0} ", x);
if (Math.Abs(x - xPrev) < eps2)
{
break;
}
xPrev = x;
}
numOfIterations += i + 1;
Console.WriteLine("Finished in {0} iterations", i + 1);
return(x);
}
static void Main(string[] args)
{
Func <double, double> fn1 = x => (x * Math.Pow(Math.E, 0.8 * x)) - 12; //Andris x*e^(0.8*x) - 12
Func <double, double> fn2 = x => (x * x * Math.Sin(x)) - 0.12; //Alina (x^2)*sinx - 0.12
Func <double, double> fn3 = x => (Math.Pow(Math.Log(x), 2) / x) - 12; //Moritz ((lnx)^2)/x - 12
Func <double, double> fn1d = x => 0.8 * Math.Pow(Math.E, (0.8 * x)) * (x + 1.25); //Andris
Func <double, double> fn2d = x => x * (x * Math.Cos(x) + 2 * Math.Sin(x)); //Alina
Func <double, double> fn3d = x => - ((-2 + Math.Log(x)) * Math.Log(x)) / Math.Pow(x, 2); //Moritz
var bisection = new Algorithms.Bisection();
Console.WriteLine("Bisection");
double a = 2;
double b = 3;
int numOfIterations = 0;
Console.WriteLine(bisection.FindRoot(ref a, ref b, 0.0001, fn1, ref numOfIterations));
Console.WriteLine(numOfIterations);
a = 3; b = 4;
numOfIterations = 0;
Console.WriteLine(bisection.FindRoot(ref a, ref b, 0.0001, fn2, ref numOfIterations));
Console.WriteLine(numOfIterations);
a = 0; b = 1;
numOfIterations = 0;
Console.WriteLine(bisection.FindRoot(ref a, ref b, 0.0001, fn3, ref numOfIterations));
Console.WriteLine(numOfIterations);
numOfIterations = 0;
Console.WriteLine();
var newtons = new Algorithms.NewtonsCombined();
Console.WriteLine("Andris x*e^(0.8*x) - 12 - Newtons Method - eps = 0.01, eps for bisection = 0.1");
newtons.FindRoot(fn1, fn1d, 2, 3, 0.1, 0.0001, ref numOfIterations);
Console.WriteLine(numOfIterations);
numOfIterations = 0;
Console.WriteLine("Alina (x^2)*sinx - 0.12 - Newtons Method - eps = 0.01, eps for bisection = 0.1");
newtons.FindRoot(fn2, fn2d, 3, 4, 0.1, 0.0001, ref numOfIterations);
Console.WriteLine(numOfIterations);
numOfIterations = 0;
Console.WriteLine("Moritz ((lnx)^2)/x - 12 - Newtons Method - eps = 0.01, eps for bisection = 0.1");
newtons.FindRoot(fn3, fn3d, 0, 1, 0.1, 0.0001, ref numOfIterations);
Console.WriteLine(numOfIterations);
Console.Read();
}
