Game math

main.cs

  		Point p = new Point ();
			p.X = 3;
			p.Y = 4;

			Point i = new Point ();
			i.X = 1;
			i.Y = 2;

			Vector v = i - p;
			Vector normalized = v.Normalized();

			Console.WriteLine ("Result: (" + normalized.X + ", " + normalized.Y + ", " + normalized.Length + ")\n");

Point.cs

using System;

namespace MacRocketFly
{
  public class Point
	{
		public float X {
			get;
			set;
		}

		public float Y {
			get;
			set;
		}

		public Point ()
		{
		}

		public Point AddVector(Vector v)
		{
			Point p2 = new Point();

			p2.X = this.X + v.X;
			p2.Y = this.Y + v.Y;

			return p2;
		}

		public static Vector operator -(Point a, Point b)
		{
			Vector v = new Vector();

			v.X = a.X - b.X;
			v.Y = a.Y - b.Y;

			return v;
		}
	}
}

vector.cs

using System;

namespace MacRocketFly
{
  public class Vector
	{
		public Vector ()
		{
			
		}

		public Vector (float x, float y)
		{
			this.X = x;
			this.Y = y;
		}

		public float X {
			get;
			set;
		}

		public float Y {
			get;
			set;
		}

		public double Length 
		{
			get 
			{
				return Math.Sqrt (X * X + Y * Y);
			}
		}

		public float LengthSqr
		{
			get 
			{
				return (X * X + Y * Y);
			}
		}

		public Vector SpeedUp(float s)
		{
		
			Vector scaled = new Vector();
			scaled.X = this.X * s;
			scaled.Y = this.Y * s;

			return scaled;
		}

		public Vector SlowDown(float s)
		{
			Vector scaled = new Vector();
			scaled.X = this.X / s;
			scaled.Y = this.Y / s;

			return scaled;
		}

		public Vector Normalized()
		{
			return new Vector (((float)X / this.Length), ((float)Y / this.Length));
		}
	}
}

http://www.youtube.com/watch?v=hh-3xLawoYo&list=PLW3Zl3wyJwWOpdhYedlD-yCB7WQoHf-My