Thread: How come the mean is 7?

How do I calculate the mean?
The answer for this case is 7.
Why?

My assignment is here(if you want to know the question but I don't think you need it to answer "my" question):
http://www.cse.yorku.ca/course/2011/...201/Q2/Q2.html

The following is the tester class:

 
/**
 * Tests the IntegralImage class.
 */
public class testIntegralImage {
 
	public static void main(String[] args) {
		int[][] image1 = {{1, 2, 3},
				       {4, 5, 6}, 
				       {7, 8, 9}};  // a 2d array. three rows, three columns.
		int top,bottom,left,right;
		double mean;
 
		IntegralImage integralImage1;
		top = 1;
		bottom = 2;
		left = 1;
		right = 2;
 
		try {
			integralImage1 = new IntegralImage(image1);
		} catch (InvalidImageException iix) {
			System.out.println("Invalid Image Exception");
			return;
		}
		try {
			mean = integralImage1.meanSubImage(top,bottom,left,right);      //should be 7.0
			System.out.println("The mean of the subimage from ("+top+","+left+") to ("+bottom+","+right+") is "+mean);
		} catch (InvalidSubImageIndexException isiix) 
		{
			System.out.println("Invalid SubImage Index Exception");
		}
 
	}
}

I'm having trouble understanding the question. I think you have to look at the 2d array and calculate the mean, given the top, left, bottom and right. How do you get 7 from this?

Originally Posted by IAmHere

I'm having trouble understanding the question. I think you have to look at the 2d array and calculate the mean, given the top, left, bottom and right. How do you get 7 from this?

The program description explains pretty clearly how to calculate the mean, and 7 is the correct answer in this case. What do you think the answer should be?