asp.net如何使Vector类支持IEnumerable接口

这问题确实太初级了，好久没用这个，忘了分请在①处添加代码，使得Vector类支持IEnumerable接口。
提示：实现GetEnumerator 方法，这需要定义一个实现了IEnumerator接口的辅助类。
using System;
using System.Collections.Generic;
namespace CollectionDemo
{
class Vector : IEnumerable
{
public double X;
public double Y;
public double Z;
public Vector(double x, double y, double z)
{
X = x; Y = y; Z = z;
}
//①
}
class Program
{
static void Main(string[] args)
{
Vector vec = new Vector(30, 100, 60);
foreach (double v in vec)
{
Console.WriteLine(v);
}
}
}
}
输出的结果为：
30
100
60

书上的例子都是用于对象，foreach怎么用于double类型，而且是在vec对象中 后要重新绑定一下数据了，恩，是要把所有的查出来，不过无所谓，内部项目，放局域网上用，懒的写分页了~

using System;
using System.Collections.Generic;
using System.Linq;
using System.Collections;
using System.Text;

namespace ConsoleApplication3
{
    class Vector : IEnumerable
    {
        public double X;
        public double Y;
        public double Z;
        public Vector(double x, double y, double z)
        {
            X = x; Y = y; Z = z;
        }
        public IEnumerator GetEnumerator()
        {
            return new MyStringEnumerator(X,Y,Z);
        }
    }
    public class MyStringEnumerator : IEnumerator
    {
        private double[] arr;
        private int index = -1;
        public MyStringEnumerator(double x,double y,double z)
        {
            arr = new double[3] {x,y,z};
        }
        public object Current
        {
            get { return arr[index]; }
        }

        public bool MoveNext()
        {
            index++;
            if (index < arr.Length)
            {
                return true;
            }
            else
            {
                return false;
            }        }

        public void Reset()
        {
            index = -1;
        }
    }
}