Storing values from a while-loop within a for-loop.

Hi, I've tried to run a while loop a hundred times with a for loop. My goal is to store the counting variable (k) from each while-loop In a vector, and then take the mean of this vector. I've coded it this way;

Q = zeros(1,100); 

for (ii) = 1 : 100  

      k = 0 ; %counting variabel 

      sum = 0;
      critical_value = 1.9;
      while sum<critical_value
          sum = rand(1) + rand(1) ;
          k = k + 1;

      end 
      Q(1,k) = k;
  end

W = mean(Q(1,k));

My problem is that the values I try to store don´t really make sense compared to what I intended it to be. The end goal of this project is to test the mean of the stored counting variables against an predetermined expected value.

Do anyone have a suggestion on how to solve my problem?

Answer 1

[Geoff Hayes]

Børge - your code seems to be counting the number of iterations (of the while loop) it takes to generate two random number whose sum is greater than 1.9. A problem may be how you update Q

 Q(1,k) = k;

If on ii=1, it takes 24 times to generate this sum (please rename this variable as sum is a built-in MATLAB function) then you are setting the 24th element of Q to 24. Wouldn't you rather have

 Q(ii) = k;

where we set the ii th iteration to be k.

Once you have done this for 100 iterations, you have an array Q of 100 iteration counts. To find the mean, you would do

 mean(Q)

instead of what you are doing which just returns the last element in your array

Or have I misunderstood how you want to compute the mean?