Syntax
SCAN(initial_value, array, lambda)
| Parameter | Description |
|---|---|
| initial_value | Parameter of the SCAN function. |
| array | Parameter of the SCAN function. |
| lambda | Parameter of the SCAN function. |
Examples
Running total (cumulative sum)
Formula
=SCAN(0, A1:A10, LAMBDA(acc, val, acc+val))
Returns 10 values showing the running total at each row. If A1:A3 is 100, 200, 300, results are 100, 300, 600.
Cumulative product
Formula
=SCAN(1, B1:B5, LAMBDA(acc, val, acc*val))
Returns the cumulative product at each step. For values 2, 3, 4: results are 2, 6, 24.
Running maximum
Formula
=SCAN(-9E+307, C1:C20, LAMBDA(mx, val, MAX(mx, val)))
Tracks the maximum value seen so far at each row. The running max never decreases — it shows the highest value encountered up to each point.
Common Errors
#VALUE!
The LAMBDA doesn't accept exactly 2 parameters (accumulator and current value).
#CALC!
The LAMBDA produces an error during one of the iterations.
Tips
SCAN vs REDUCE
REDUCE gives you one final value; SCAN gives you an array showing every intermediate value along the way. Use SCAN when you need the full trail, not just the end result.
Running balance in bank statement
=SCAN(startingBalance, transactions, LAMBDA(bal, txn, bal+txn)) creates a running balance column from a list of deposits and withdrawals.
Choose initial value carefully
For running sums, start with 0. For running products, start with 1. For running max, start with a very small number or the first element itself.
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