using System;

public class Program

{

    public static void Main()

    {

        var obj = new Interpolator() 

        {

            Constant = 1.0,

            Value = 2.0

        };

        Console.WriteLine(obj.ToString());

        obj.Value = 4.0;

        Console.WriteLine(obj.ToString());

        obj.Constant = 2.5;

        Console.WriteLine(obj.ToString());

    }   

}

​

public class Interpolator

{

    public double Constant {get; set;} //array[0]

    public double Value {get; set;}    //array[3]

    public double Interpolation1 { get { return CalculateInterpolation1(); } }

    public double Interpolation2 { get { return CalculateInterpolation2(); } }

    private double CalculateInterpolation1()

    {

        //define your interpolation here

        return this.Constant + ((this.Value - this.Constant) / 3.0);

    }

    private double CalculateInterpolation2()

    {

        //define your interpolation here

        return this.Constant + ((this.Value - this.Constant) * 2.0 / 3.0);

    }       

    public override string ToString() 

    {

        return String.Format("Constant: {0:f3}, Interpolation1: {1:f3}, Interpolation2: {2:f3}, Value: {3:f3}"

                                , this.Constant, this.Interpolation1, this.Interpolation2, this.Value);

    }

}

​