help with summing array (sigma sigma)

8 次查看（过去 30 天）
sam
sam 2013-6-15
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

请先登录，再回答此问题。

回答（1 个）

Image Analyst
Image Analyst 2013-6-15
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
  2 个评论
Image Analyst
Image Analyst 2013-6-15
编辑：Image Analyst 2013-6-15
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
Image Analyst 2013-6-15
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.

请先登录，再进行评论。

类别

在 Help Center 和 File Exchange 中查找有关 Loops and Conditional Statements 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by