I have a problem about below question. Cab anybody help me??

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SULE SAHIN 2017-10-27

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评论： Walter Roberson 2018-4-27

Write a function called peri_sum that computes the sum of the elements of an input matrix A that are on the “perimeter” of A. In other words, it adds together the elements that are in the first and last rows and columns. Note that the smallest dimension of A is at least 2, but you do not need to check this. Hint: do not double count any elements!

My answer is ;

function sumofthelements = peri_sum(A)
    sumofthelements = A(1,1) + A(1,end) + A(end,1) + A(end,end);

I know that I calculate corner sum but I didn't calculate perimeter of A matrix

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Walter Roberson 2018-4-27

Please do not close questions that have an answer.

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Answer 1

Roger Stafford 2017-10-27

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You have only the sum of the four corners of the matrix. Hint: A(1,:) is a vector consisting of the top row elements of A. How can you use it? What about the other parts of the perimeter?

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SULE SAHIN 2017-10-27

Thank you your hint. function x = peri_sum(A) y = A(1,:) + A(end,:) + A(:,1) + A(:,end); c = sum(y); x = c- (A(1,1) + A(1,end) + A(end,1) + A(end,end)); I thougt this type but this is wrong too.

SULE SAHIN 2017-10-27

My correct answer is; function x = peri_sum(A) x = sum(A(1,:)) + sum(A(end,:)) + sum(A(:,1)) + sum(A(:,end)) - ( A(1,1) + A(1,end) + A(end,1) + A(end,end))

Thank you for your helps

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