Dynamically referencing above rows in the same column

Greg_Deckler 
This is a nice example of pseudo-recursive calculation that might be helpful to you for your new book.

NaveenMD 
There is no fixed pattern for what I call "Semi-Recursive" calculations.

Referring to the previous row in the same column that is under evalution is not possible in Power Bi as the whole column is evaluated as set not cell by cell as the case in excel. However, we can trace back the the calculation of the previous cell to notice that it is actually evaluated the existing values of other (existing) columns and the cell previous to it and so on until we reach to the very first cell which is being totally evaluated from other existing column(s).

This would require taking some advantage of mathmics. Assuming quantity column "Q" and (1 - [Ratio]) is R then we can write

Row1: 
= Q1

Row2:
= Q1*R2 + Q2

Row3:
= (Row2)*R3 + Q3
= (Q1*R2 + Q2)*R3 + Q3
= Q1*R2*R3 + Q2*R3 + Q4

Similarly Row4 would be:
= Q1*R2*R3*R4 + Q2*R3*R4 + Q3*R4 + Q4

And so on...

If we look closely to Row4 

Now it is a matter to find the tables that need to be iterated inside each of these two iterators. The rest is just fine tuning some details.

Closing Stock 2 = 
VAR MinIndex = MINX ( FILTER ( 'Table', 'Table'[Material QTY] > 0 ), 'Table'[Index] )
VAR T1 = FILTER ( 'Table', 'Table'[Index] <= EARLIER ( 'Table'[Index] ) )
RETURN 
    SUMX ( 
        T1,
        VAR Qty = 'Table'[Material QTY]
        VAR T2 = FILTER ( T1, 'Table'[Index] > EARLIER ( 'Table'[Index] ) )
        VAR Rate = 
            COALESCE(
                PRODUCTX ( 
                    T2, 
                    1 - 'Table'[Rate]
                ),
                1
            )
        RETURN
            Qty * Rate
    )