help with summing array (sigma sigma)

Q Write a m-file e74.m that generates a random matrix A that is always 200 in width, and calculates the sum Σ Σ Where A is of width 200 and height H. The file e74.m should use a nested for-loop (two for loops nested in each other).

sorry for the previous incorrect format

this is what i have so far..... Better?

SumOfNumbers=0
SumOfNumbers= SumOfNumbers + A(j,k)^2
[rows,columns] = Size(A) 
for j=1:200 % row index
  for k=1:n % column index
    disp(A(k,j))
  end

Answer 1

[Image Analyst]

Huh? You have 3 for loops instead of two (one over rows and one over columns). What is the loop over n for? Plus, you aren't doing any summing at all! Where is the sum line, like theSum = theSum + A(k,j)????

Next, the width is 200 columns ( not the height), so why are you iterating over 200 rows instead of 200 columns?

Please read this to learn how to format your code:

http://www.mathworks.com/matlabcentral/answers/13205-tutorial-how-to-format-your-question-with-markup

[Image Analyst]

Regarding your edit: you don't need the first 3 lines. You need another end to finish the first for loop, and you need a summing line like I already told you, plus you need to initialize theSum to zero before the loops. Plus your for loop limits are wrong. Hint:

[rows, columns] = size(A)

Use rows and columns in the for loop.

[Image Analyst]

Getting better, but you still didn't read my comment above because you haven't implemented most of the fixes I told you. Please read it again and do some of the things - all of them actually.