docs: public static void statistics( List<Point3D_F64> cloud , Point3D_F64 mean , Point3D_F64 stdev ) {
  		final int N = cloud.size();
  		for (int i = 0; i < N; i++) {
  			Point3D_F64 p = cloud.get(i);
  			mean.x += p.x / N;
  			mean.y += p.y / N;
  			mean.z += p.z / N;
  		}
  
  		for (int i = 0; i < N; i++) {
  			Point3D_F64 p = cloud.get(i);
  			double dx = p.x-mean.x;
  			double dy = p.y-mean.y;
  			double dz = p.z-mean.z;
  
  			stdev.x += dx*dx/N;
  			stdev.y += dy*dy/N;
  			stdev.z += dz*dz/N;
  		}
  		stdev.x = Math.sqrt(stdev.x);
  		stdev.y = Math.sqrt(stdev.y);
  		stdev.z = Math.sqrt(stdev.z);
  	}