Gauss-Seidel

/**
 * Copyright uwi ( http://wonderfl.net/user/uwi )
 * MIT License ( http://www.opensource.org/licenses/mit-license.php )
 * Downloaded from: http://wonderfl.net/c/8Dtb
 */

package {
    import flash.display.Sprite;
    import flash.text.TextField;
    import flash.utils.getTimer;
    public class Test extends Sprite {
        private var _tf : TextField;
  
        public function Test() {
            _tf = new TextField();
            _tf.width = 465;
            _tf.height = 465;
            addChild(_tf);
            
            var s : int = getTimer();
            
            tr(GS([
                3, -1, 1,
                3, 6, 2,
                3, 3, 7
                ], [
                1, 0, 4
                ], 100, 0.0001).join('\n'));
            
            var g : int = getTimer();
            tr((g - s) + " ms");
        }
        
        private function GS(a : Array, b : Array, N : int, TOL : Number) : Array
        {
            var n : int = b.length;
            if(n == 0 || a.length != n * n)return null;
            var x : Array = new Array(n);
            var i : int, j : int;
            for(i = 0;i < n;i++){
                x[i] = 0.0;
            }
            
            for(var k : int = 1;k <= N;k++){
                var xo : Array = x.concat();
                for(i = 0;i < n;i++){
                    var sum : Number = 0.0;
                    for(j = 0;j < n;j++){
                        if(i != j){
                            sum += a[i * n + j] * xo[j];
                        }
                    }
                    x[i] = (-sum + b[i]) / a[i * n + i];
                }
                
                var norm : Number = 0.0;
                for(i = 0;i < n;i++){
                    norm += (x[i] - xo[i]) * (x[i] - xo[i]);
                }
                if(norm < TOL){
                    return x;
                }
            }
            return null;
        }

        private function tr(...o : Array) : void
        {
            _tf.appendText(o + "\n");
        }
    }
}