How to sum up different values of a matrix?

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Mato Lab
Mato Lab 2016-10-10
评论： dpb 2016-10-11
Hello,
I have a matrix A containing 1000 values. I want to calculate the cumsun of the element 1 to 10, 10 to 20, 20 to 30 etc.I dont want to use a loop (for or when). Only matrix maipluation formulas.
Can you advise how I could do that?

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回答（2 个）

dpb
dpb 2016-10-10
编辑：dpb 2016-10-11
doc arrayfun % and hide the looping construct (but it's still there)
ADDENDUM
Actually, "what was I thinking?" :) Besides the wrong function name, while can do it that way, "the Matlab way" is
windowSize = 1000;
cumsum=conv(data,ones(1,windowSizend),'valid');
The sum is nothing but the mean w/o being normalized by the number of elements in the window.
Kwin
Kwin 2016-10-11
You can reshape the matrix such that it MATLAB only calculates the cumsum of the appropriate values:
B = cumsum(reshape(A, 10, length(A)/10))';
But if A is not a single row, you might have to do some addition reshaping to ensure that each sequence of data is in its own column (and maybe add some zeros is to make sure that the row length you are splitting up is a multiple of 10.
  1 个评论
dpb
dpb 2016-10-11
B = cumsum(reshape(A, 10, length(A)/10))';
This is good place for the empty braces idiom...
B=cumsum(reshape(A, 10, []).';

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