Thread: Fibonacci Spiral Help?

I'm trying to write a Java program that will display the Fibonacci Spiral as shown here . For right now, I just have it printing the starting coordinates of the rectangle that's being drawn, along with its length. There's nothing wrong with my program, except for a little array problem that I can fix, but I think there is a fundamental flaw in my thinking for this program. Can someone take a look at my code below and see why it does not work?
*Note: This is a school project, so I don't want too much help telling me what I should do, I just need help telling me what I shouldn't have done and why.
Thanks!

public class FibSpiralPanel extends JPanel{
 
	public void paintComponent(Graphics g){
		super.paintComponent(g);
 
		int xCenter = getWidth()/2;
		int yCenter = getHeight()/2;
		int x=0, number, nextNumber = 0, count;
		int[] xStart = {0,0,0,0,0,0,0,0}, yStart={0,0,0,0,0,0,0,0};
 
		xStart[0] = xCenter;
		yStart[0] = yCenter;
 
		for(x=1; x<5; x++){
			number = (int)Fibonacci.getFibonacci(x);  //Get the length of the square.
 
 
 
			if(x%4 == 0){
				xStart[x] = xStart[x-1] - number;
				yStart[x] = yStart[x-1];
			}
 
			else if(x%3==0){
				xStart[x] = xStart[x-3];
				yStart[x] = yStart[x-3] - number;
			}
 
			else if(x%2 ==0){
				xStart[x] = xStart[x-2] + number;
				yStart[x] = yStart[x-2];
			}
 
			else{
				xStart[x] = xStart[x-1];
				yStart[x] = yStart[x-1] + number;
 
			}
			System.out.println("Fibonacci "+x+" is "+number);
			System.out.println("xStart: "+xStart[x]+"\nyStart: "+yStart[x]);
		}				
	}
}

Inspect the way the code determines the location of a Fibonacci square (eg the uses of modulus). My understanding is that the squares are repetitive in fours, and so checking the remainder from dividing by 4 may be more appropriate. Also, I assume the getFibonacci method returns the value at position x in the series? Because that code isn't listed I'll just comment that this is in the loop of a drawing routine so it should be fast (precalculated)

Originally Posted by helloworld922

Calculating Fibonacci can be fast... O(n) with O(1) memory space

I dislike big O notation, mainly because I stink at calculating it ...but do that in a loop it becomes something like O(n*n) (I know I know, we're talking a loop of five here though )

I'll second Helloworld's advice on working with corners, especially if you plan to do the drawing using g.drawArc(...)