using System;

public class Test
{
	public static void Main()
	{
		double[] array = new double[] {1,2,3,4,5};
		var indexer1 = new Index(array, 1, 2); 
		Console.WriteLine(indexer1[0]);
	}
	
class Index {
    private readonly double[] arr;
    private readonly int offset; // set this to x in the constructor
    public int Length { get { return arr.Length; } }
    public double this[int idx] {
        get { return arr[idx+offset]; }
        set { arr[idx+offset] = value; }
    }
    public Index(double[] arr1, int x, int y) {
        arr = arr1;
        offset = x;
    }
}
	
	
	
}