fyd-comment-keith.txt

formula
=LET(
    nums, SEQUENCE(10,,,RAND()*10),
    data, SCAN(
        0,
        nums,
        LAMBDA(a, v,
            LET(
                //get the value from the current row of the array
                current, INDEX(nums, v, 1),
                //get the value from the previous row of the array
                previous, INDEX(nums, v - 1, 1),
                //if nums-1 is zero, previous is the entire array, so use a default instead
                //in this example, I've used zero as the default
                previous_adj, IF(ROWS(previous) > 1, 0, previous),
                //example calculation involving a, current and previous
                a + ABS(current - previous_adj)
            )
        )
    ),
    data
)