Sum over columns excluding rows

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Javier
Javier 2014-1-13
评论： Javier 2014-1-14
Hi, I am quite a begginer with matlab and I wonder if someone could help me with this problem.
I have a matrix
A=[a b c d;
e f g h;
i j k l;
m n o p]
I want to get the sum of each row and then perform the same operating excluding the first column, then excluding the first two columns and then the first three columns and put all this results in a matrix. I want something like this
B=[a+b+c+d b+c+d c+d d;
e+f+g+h f+g+h g+h h;
i+j+k+l j+k+l k+l l;
m+n+o+p n+o+p o+p p]
Do you know how can I get the this result in a effiicient way? I have four columns in the example but more than 10,000 in the real problem.
Thank you in advance. Javier

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采纳的回答

José-Luis
José-Luis 2014-1-13
编辑：José-Luis 2014-1-13
your_mat = flipud(cumsum(flipud(A')))'
  1 个评论
Javier
Javier 2014-1-14
This works perfectly, I did not know these functions. Thank you very much!!

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更多回答（1 个）

Azzi Abdelmalek
Azzi Abdelmalek 2014-1-13
编辑：Azzi Abdelmalek 2014-1-13
A = [1 2 3 4; 2 4 6 0; 3 1 2 5; 1 1 1 3]
out=fliplr(cumsum(fliplr(A),2))

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