Sum over columns excluding rows

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

Answer 1

[José-Luis]

your_mat = flipud(cumsum(flipud(A')))'

[Javier]

This works perfectly, I did not know these functions. Thank you very much!!

Answer 2

[Azzi Abdelmalek]

A = [1 2 3 4; 2 4 6 0; 3 1 2 5; 1 1 1 3]
out=fliplr(cumsum(fliplr(A),2))

[Javier]

Thank you very much!