Delegates

using System;
delegate double Function(double x);
class Multiplier
{
    double factor;
    public Multiplier(double factor) {
        this.factor = factor;
    }
    public double Multiply(double x) {
        return x * factor;
    }
}
class Test
{
    static double Square(double x) {
        return x * x;
    }
    static double[] Apply(double[] a, Function f) {
        double[] result = new double[a.Length];
        for (int i = 0; i < a.Length; i++) result[i] = f(a[i]);
        return result;
    }
    static void Main() {
        double[] a = {0.0, 0.5, 1.0};
        double[] squares = Apply(a, Square);
        double[] sines = Apply(a, Math.Sin);
        Multiplier m = new Multiplier(2.0);
        double[] doubles =  Apply(a, m.Multiply);
    }
}
// Souce: CSharp Language Specification