private void checkFirstOrder(){
		SVA_Sketch sketch = sketchQueue[(tail-1) % MAX_QUEUE_SIZE];
		Timestamp currentTime = sketch.time;
		System.out.println("Checking..." + currentTime);
		{
			double s = sketch.s.zeroOrder.getValue(currentTime, 0);
			for(int h = 0; h < H; h ++){
				double C = 0;
				for(int i = 0; i < N; i ++){
					C += sketch.s.firstOrder[h][i].getValue(currentTime, 0);
				}
				if(C != s) System.out.println("S Error!" + h + " " + Math.abs(C - s) + " " + s);
			}	
		}
		
		{
			double v = sketch.v.zeroOrder.getValue(currentTime, smoothLength1 * oneMinute);
			for(int h = 0; h < H; h ++){
				double C = 0;
				for(int i = 0; i < N; i ++){
					C += sketch.v.firstOrder[h][i].getValue(currentTime, smoothLength1 * oneMinute);
				}
				if(C != v) System.out.println("V Error!" + h + " " + Math.abs(C - v) + " " + v);
			}	
		}
		
		{
			double a = sketch.a.zeroOrder.getValue(currentTime, smoothLength2 * oneMinute);
			for(int h = 0; h < H; h ++){
				double C = 0;
				for(int i = 0; i < N; i ++){
					C += sketch.a.firstOrder[h][i].getValue(currentTime, smoothLength2 * oneMinute);
				}
				if(C != a) System.out.println("A Error!" + h + " " + (C - a) + " " + a);
			}	
		}
	}