java由点绘图

我做到是基于IFS的绘图有一段程序如下：
double a1,a2,a3,a4,a5,a6,b1,b2,c1,c2;
e.fillOval(s.x, s.y, 5, 5);  
double arr[][]=new double[][]{{0.08,0,0,0.5,0,0,0.1},{0.836,0.044,-0.044,0.836,0,0.169,0.5},{-0.141,0.302,0.302,0.141,0,0.127,0.2},{0.141,-0.302,0.302,0.141,0,0.169,0.2}}; 
for(int i=1;i<20000;i++){
        double p=Math.random();
           if(p<arr[0][6]){
                a1=arr[0][0];
                a2=arr[0][1];
                a3=arr[0][2];
                a4=arr[0][4];
                a5=arr[0][5];
                a6=arr[0][6];        }
           else if(p<(arr[0][6]+arr[1][6])){
                a1=arr[1][0];
                a2=arr[1][1];
                a3=arr[1][2];
                a4=arr[1][4];
                a5=arr[1][5];
                a6=arr[1][6];           }
           else if(p<(arr[0][6]+arr[1][6]+arr[2][6])){
                        a1=arr[2][0];
                        a2=arr[2][1];
                        a3=arr[2][2];
                        a4=arr[2][4];
                        a5=arr[2][5];
                        a6=arr[2][6];     }
    else if(p<=1){
                        a1=arr[3][0];
                        a2=arr[3][1];
                        a3=arr[3][2];
                        a4=arr[3][4];
                        a5=arr[3][5];
                        a6=arr[3][6];
     }
          b1=s.x;b2=s.y;
          s.x=a1*b1+a2*b2+a5;
          s.y=a3*b1+a4*b2+a6;
          e.fillOval(s.x, s.y, 5, 5);
    }   
} 
基本意思是根据一个随即数，随即套用公式，得出一种蕨类的图片，可计算出的坐标是小数，请问该怎样画点