Expalin formula

[sohaila]

KINDLY EXPLAIN THIS FORMULA
THANKS


REDUCE(0,H7:H10,LAMBDA(a,b,VSTACK(TAKE(a,1),a+b)))
H FORMULA REDUCE(0,H7:H10,LAMBDA(a,b,VSTACK(TAKE(a,1),a+b)))

1	0
2	4
3	7
4	9
	10

 

[sohaila]

Kindly help

 

[hagia_sofia]

If you use =REDUCE(0,A1:A4,LAMBDA(a,b,b)) on 1, 2, 3, 4 it returns the value last of the last row as a result, i.e. 4. The formula above does that for every row of 1, 2, 3, 4 (or 4, 3, 2, 1) and adds the result of previous calculation (a+b) to it, i.e.

1st step is 4 + initial value of a which is 0, therefore 4,
2nd step is 3 + the result of previous iteration, i.e. 4, therefore 3+4 = 7,
3rd step is 2 + 7, i.e. 9
4th step 1 + 9, i.e. 10.

The same output (although sorted in reverse order) could be achieved e.g. with =INDEX(A4,0,0)+B5 placed into B4 and copied up where B5 is 0.

 

[sohaila]

THANKS SOFIA FOR YOUR EXPLANATION IS IT POSSIABLE REDUCE ACT LIKE SCAN FUNCTION

 

[hagia_sofia]

It kind of operates like it here thanks to its combination with VSTACK. If the input would be 4, 3, 2, 1, then =VSTACK(0,SCAN(0,A1:A4,LAMBDA(x,y,x+y))) would return the same output.

 

[sohaila]

1	1
2	3
3	6
4	10

IS IT POSSIABLE IN REDUCE FUNCTION

 

[hagia_sofia]

Why not use SCAN?

 

[sohaila]

JUST FOR UNDERSTAND REDUCE FUNCTION

 

[hagia_sofia]

I guess that if you would sort 1, 2, 3, 4 in descending order with SORT function and then use the original formula, it should return 0, 1, 3, 6, 10.

 

[sohaila]

OK THANKS FOR YOUR EXPLNATION