List<double[]> x = new ArrayList<double[]>();
x.add(new double[]={1,2,3,4,54,6});
List<double[]> x = new ArrayList<double[]>();
xList<double[]> x = new ArrayList<double[]>();
x.add(new double[]={1,2,3,4,54,6});
List<double[]> x = new ArrayList<double[]>();
x