The DECUMULATE function calculates the difference between the values of the current and previous periods.

For example, you can use DECUMULATE to create a rolling comparison of the current month's performance relative to the previous month.

DECUMULATE(Value to subtract)

 Argument Data type Description Value to subtract Number The data to subtract the value of the previous period from the current period for.

The DECUMULATE function returns a number.

The time range used for the Value to subtract argument must match the time range for the result line item.

In Polaris, you cannot use DECUMULATE in formulas of line items with a formula summary method. In the Classic Engine, you can.

In this example, the DECUMULATE function is used to calculate the change in profit each month. Note that there is no period before Jan 21, so DECUMULATE returns the value for Jan 21.

 Jan 21 Feb 21 Mar 21 Apr 21 May 21 Jun 21 Jul 21 Aug 21 Sep 21 Oct 21 Nov 21 Dec 21 Operating Profit $59,730$59,124 $59, 993$59,494 $58,817$59,833 $58,945$58,654 $56,592$59,603 $58,727$59,567 Month on month change DECUMULATE(Operating Profit) 59,730 -605.5 868.4 -499 -676.7 1,016 -888.7 -290.4 -2,062 3,011 -875.4 840.1