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<html xmlns="http://www.w3.org/1999/xhtml" id="html">
	<head>
		<title>The N-Body Simulation</title>
	</head>
	<body style="margin: 0; background-image: url('/images/stars/space-the-final-frontier.jpg'); background-repeat: repeat;">
		<div id='space' style="width: 100%; height: 100%;">
			<img src="/images/stars/space-the-final-frontier.jpg" width="500" height="500"/>
		</div>
	</body>
		<script type="text/javascript">
			//Universal Constants
			var AU	= 1.49598E+11;								//m = Astronomical Unit (distance between earth in sun) 
			var	G	= 5.764608E-4;                                  //5.7646078E-08;							//Constant of Gravity
			var KG  = 1E+03;									//g = Kilograms
			
			var colors =
			[
				'#FFFFFF',
				'#007F00',
				'#FFCC00',
				'#FF6633',
				'#FF0000',
				'#CC33CC',
				'#7F00FF',
				'#0000FF'
			];
			
			var b = document.getElementById("html");
			var height	= b.offsetHeight;
			var width	= b.offsetWidth;
			
			var centerx = width / 2;
			var centery = height / 2;
	        
	        
	          
			var ZZ = 0;
			
			function Velocity(x, y, z)
			{
				this.x = x;
				this.y = y;
			}
			
			Velocity.prototype.Add = function(a)
			{
				this.x += a.x;
				this.y += a.y;
			}
			
			function Position(x, y, z)
			{
				this.x = x;
				this.y = y;
			}
			
			Position.prototype.Add = function(a)
			{
				this.x += a.x;
				this.y += a.y;
			}
			
			function Body(position, velocity, mass)
			{
				this.position		= position;
				this.velocity		= velocity;
				this.mass			= mass;
				
				this.element		= null;
				this.thumb			= null;
				this.color			= colors[ZZ % colors.length];
				
				this.trails         = [];
				for(var i = 0; i < 100; i++)
					this.trails[i] = null;
				this.trailptr       = 0;
				
				ZZ++;
			}
			
			Body.prototype.Distance = function(p)
			{
				var	deltax = p.position.x - this.position.x;
				var deltay = p.position.y - this.position.y;
				
				return Math.sqrt((deltax * deltax) + (deltay * deltay));
			}
			
			Body.prototype.Gravity = function(p)
			{
				var	deltax = p.position.x - this.position.x;
				var deltay = p.position.y - this.position.y;
				
				var distance = Math.sqrt((deltax * deltax) + (deltay * deltay));
				
				var accel = (G / (distance * distance)) * p.mass;
				
				this.acceleration.Add(new Velocity((deltax/distance) * accel, (deltay/distance) * accel));
			}
			
			Body.prototype.Plot = function()
			{
				var x = Math.round(centerx + (this.position.x * 25/AU));
				var y = Math.round(centery - (this.position.y * 25/AU));
				

				if(this.trails[this.trailptr] == null)
				{
					var doc = document.getElementById('space');
					this.trails[this.trailptr]	= doc.appendChild(document.createElement('div'));
					this.trails[this.trailptr].style.position	= 'absolute';
					this.trails[this.trailptr].innerHTML		= '·';
					this.trails[this.trailptr].style.color      = this.color;
					this.trails[this.trailptr].style.visibility	= 'visible';
				}
				this.trails[this.trailptr].style.left   = x + "px";
				this.trails[this.trailptr].style.top    = y + "px";
				
				this.trailptr = (this.trailptr + 1) % 100;			

				
				if(this.element == null)
				{
					var doc			= document.getElementById('space');
					this.element	= doc.appendChild(document.createElement('div'));
					this.element.style.position		= 'absolute';
					this.element.innerHTML			= '●';
					this.element.style.color        = this.color;
					this.element.style.visibility	= 'visible';
				}
				
				this.element.style.left			= x + "px";
				this.element.style.top			= y + "px";

	/*			
				var x = Math.round(25 + this.position.x / 40);
				var y = Math.round(25 - this.position.y / 40);

				if(this.thumb == null)
				{
					var doc = document.getElementById('space');
					this.thumb	= doc.appendChild(document.createElement('div'));
					this.thumb.style.position	= 'absolute';
					this.thumb.innerHTML		= '▪';
					this.thumb.style.color      = this.color;
				}
				
				if(x < 0 || y < 0 || x > 50 || y > 50)
				{
				}
				else
				{
					this.thumb.style.left			= x + "px";
					this.thumb.style.top			= y + "px";			
				}
	*/
			} 
			
			Body.prototype.Destroy = function()
			{
				var doc = document.getElementById('space');
			    
				for(var i = 0; i < 100; i++)
				{
					if(this.trails[i] != null)
						doc.removeChild(this.trails[i]);
				}
				doc.removeChild(this.element);
			}

			
			Body.prototype.Reset = function()
			{
				this.acceleration = new Velocity(0, 0);
			}
				
			function MoveAll()
			{
				var i1;
				var i2;
				
				for(i1 in Bodies)
					Bodies[i1].Reset();
					
				var timeScale = 10;

				for(var i = 0; i < 1; i++)
				{
					for(i1 in Bodies)
						Bodies[i1].Reset();

					for(i1 in Bodies)
					{
						var body1 = Bodies[i1];
						
						body1.position.x += body1.velocity.x;
						body1.position.y += body1.velocity.y;
					}
					
					for(i1 in Bodies)
					{
						var body1 = Bodies[i1];
						
						for(i2 in Bodies)
						{
							var body2 = Bodies[i2];
							
							if(body1 != body2)
							{
								body1.Gravity(body2);
							}
						}
					}
					
					for(i1 in Bodies)
					{
						var body1 = Bodies[i1];
						
						body1.velocity.x += body1.acceleration.x;
						body1.velocity.y += body1.acceleration.y;
					}
				}	

				var x0 = Bodies[0].position.x;
				var y0 = Bodies[0].position.y;
				
				for(i1 in Bodies)
				{
					Bodies[i1].position.x -= x0;
					Bodies[i1].position.y -= y0;
				}
			
				for(i1 in Bodies)
					Bodies[i1].Plot();

	//			for(i1 in Bodies)
	//			{
	//				if(Bodies[i1].Distance(Bodies[0]) > 1000)
	//				{
	//				    Bodies[i1].Destroy();
	//					Bodies[i1] = new Body(new Position(Bodies[0].position.x + Math.random() * 400 - 200, Bodies[0].position.y + Math.random() * 400 - 200), new Velocity(Bodies[0].velocity.x + Math.random() * 20 - 10, Bodies[0].velocity.y + Math.random() * 20 - 10), Math.random() * 100000);
	//				}
	//			}
						
				setTimeout(MoveAll, timeScale);
			}
							


			var Bodies =
			[
				new Body(new Position( 0.000000000000000E+00 * AU,  0.000000000000000E+00 * AU,  0.000000000000000E+00 * AU), new Velocity( 0.000000000000000E+00 * AU,  0.000000000000000E+00 * AU,  0.000000000000000E+00 * AU), 1.9891E30 * KG),	//SUN
				new Body(new Position(-1.101694065133387E-02 * AU, -4.627459946836336E-01 * AU, -3.679439537218468E-02 * AU), new Velocity( 2.248379877130665E-02 * AU,  7.741832622393350E-04 * AU, -2.000052808785571E-03 * AU), 3.3020E23 * KG),	//MERCURY
				new Body(new Position( 5.378357762066760E-01 * AU, -4.894694874779497E-01 * AU, -3.773990054258105E-02 * AU), new Velocity( 1.348318340906038E-02 * AU,  1.488292046997766E-02 * AU, -5.745425614074939E-04 * AU), 4.8685E24 * KG),	//VENUS
				new Body(new Position(-1.721041076989816E-01 * AU,  9.681072708702687E-01 * AU, -1.766288579466907E-05 * AU), new Velocity(-1.721235722280550E-02 * AU, -3.078469223808449E-03 * AU, -7.775930922984637E-08 * AU), 5.9736E24 * KG),	//EARTH
				new Body(new Position(-1.711423088734627E-01 * AU,  9.704079886563293E-01 * AU,  1.977776822205624E-04 * AU), new Velocity(-1.776717093979287E-02 * AU, -2.831034837693510E-03 * AU,  1.176624807323343E-05 * AU), 7.3490E22 * KG),	//LUNA
				new Body(new Position(-6.538074989187658E-01 * AU, -1.366082079817985E+00 * AU, -1.256065550271462E-02 * AU), new Velocity( 1.315073618350288E-02 * AU, -4.841752535151738E-03 * AU, -4.244775139504463E-04 * AU), 6.4185E23 * KG),	//MARS
				new Body(new Position(-2.474679193883905E+00 * AU, -4.760524109817909E+00 * AU,  7.513884588477229E-02 * AU), new Velocity( 6.607795008478355E-03 * AU, -3.128453163660247E-03 * AU, -1.348870163475158E-04 * AU), 1.8986E27 * KG),	//JUPITER
				new Body(new Position(-7.036502535576534E+00 * AU,  5.889824512924870E+00 * AU,  1.774740254592805E-01 * AU), new Velocity(-3.875709133420537E-03 * AU, -4.293214645210232E-03 * AU,  2.289367285693264E-04 * AU), 5.6846E26 * KG),	//SATURN
				new Body(new Position( 1.929821276495023E+01 * AU, -5.567836856202042E+00 * AU, -2.706233576472611E-01 * AU), new Velocity( 1.066081900379735E-03 * AU,  3.592026863127670E-03 * AU, -4.155804968605364E-07 * AU), 8.6832E25 * KG),	//URANUS
				new Body(new Position( 2.273883666063009E+01 * AU, -1.964575868056128E+01 * AU, -1.194993987923258E-01 * AU), new Velocity( 2.036182236634615E-03 * AU,  2.389806450959143E-03 * AU, -9.625143587760285E-05 * AU), 1.0243E26 * KG),	//NEPTUNE
				new Body(new Position(-1.879727866016690E+00 * AU, -3.092476101835807E+01 * AU,  3.851834990016669E+00 * AU), new Velocity( 3.191271345796025E-03 * AU, -7.835406400933414E-04 * AU, -8.486375416093025E-04 * AU), 1.3140E22 * KG),	//PLUTO
				new Body(new Position(-1.879812026227606E+00 * AU, -3.092479340918641E+01 * AU,  3.851930281176825E+00 * AU), new Velocity( 3.237429931649916E-03 * AU, -6.880690707329203E-04 * AU, -7.757127200856482E-04 * AU), 1.9000E21 * KG),	//CHARON
				//new Body(new Position( 1.000000000000000E+01 * AU,  3.000000000000000E+00 * AU,  0.000000000000000E+00 * AU), new Velocity(-1.000000000000000E-01 * AU,  0.000000000000000E-00 * AU, -0.000000000000000E-00 * AU), 1.0000E31 * KG),	//DEATH!
			]
			
					
			setTimeout(MoveAll, 1);
		</script>
</html>
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