Cumulated sum of elements of each column of a matrix

The cumSum command finds the cumulated sum of each column of a matrix (see also Section 6.3.26).

cumSum takes A, a matrix.
cumSum(A) returns the matrix whose columns are the cumulated sum of the elements of the corresponding column of the matrix A.

cumSum([[1,2],[3,4],[5,6]])

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since the cumulated sums of the first column are: 1, 1+3=4, 1+3+5=9 and the accumulated sums of the second column are: 2, 2+4=6, 2+4+6=12.