銀河の膨張

using System;

namespace ExpandingGalaxy
{
	public class Point
	{
		public Point( double x, double y )
		{
			this.x = x;
			this.y = y;
		}
		public double x { get; set; }
		public double y { get; set; }
	}
	
	public class MainClass
	{
		const double H = 3.5;
		const double DT = 0.1;

		private static Point[] Calc()
		{

			const int RANDOM_MAX = 21478643;
			const int SEED = 503;
			
			double x, y;
			Point[] points = new Point[200];
			Random rand = new Random( SEED );
			int i = 0;
			
			while( true )
			{
				x = ( double )( 1.0 / RANDOM_MAX * rand.Next( -100000000, 100000000 ) );
				y = ( double )( 1.0 / RANDOM_MAX * rand.Next( -100000000, 100000000 ) );
				if( Math.Pow( x, 2 ) + Math.Pow( y, 2 ) <= 1.0 )
				{
					points[i] = new Point( x, y );
					i++;
					if( ( i == 200 ) )
					    break;
				}
			}
			return points;
		}

		private static void ExpandingSimulate( Point[] points, Point[] vxPoints )
		{
			for( int i = 0; i < points.Length; i++ )
			{
				points[i].x += vxPoints[i].x * DT;
				points[i].y += vxPoints[i].y * DT;
			}
		}

		private static Point[] GetVxValue( Point[] points )
		{
			Point[] vxPoint = new Point[200];
			for( int i = 0; i < points.Length; i++ )
			{
				vxPoint[i] = new Point( points[i].x * H, points[i].y * H );
			}

			return vxPoint;
		}

		public static void Main( string[] args )
		{
			Point[] points0 = Calc();
			Point[] vxPoint = GetVxValue( points0 );
			
			for( int i = 0; i < points0.Length; i++ )
			{
				points0[i].x += 10;
				points0[i].y += 10;
			}

			using( System.IO.StreamWriter writer = new System.IO.StreamWriter( @"data.csv" ) )
			{
				for( int i = 0; i < 20; i++ )
				{
					ExpandingSimulate( points0, vxPoint );
					if( ( i == 0 ) || ( i == 5 ) || ( i == 19 ) )
					{
					    for( int j = 0; j < points0.Length; j++ )
					    	 writer.WriteLine( "{0}, {1}", points0[j].x, points0[j].y );
					    writer.WriteLine();
					}
				}
			}
		}
	}
}