Function to perform subsequent subtraction in BEx

Hello Experts,

I want to build following standard deviation formula in BEx.

std = R-Bar/D2, R-Bar defined as the sum of the absolute values of the differences between the value and the value before it divided by the number of values (the number of values will be the count minus 1 since the first value does not have a value to take a difference from).  D2 is a contant 1.128.

I don't get any function to perform subsequent subtraction.

, in spreadsheet it is something like this.

Column D : Actual Test Results of Lot 'L1' for each sample (A to G)

Now I need to calculate its standard deviation using above formula.

Column F : E3-E2, E4-E3 and so on. In E2, value will be Zero as it's the first record.

Column G : Absolute of Values in Column F.

Cell G10 : Sum of all absolute values (60 in this example)

Cell G12 : Sum/ (Count-1) i.e. 60/(7-1) in this example. A to G are 7 samples, so count is 7.

G14 : G12/1.128

So, G14 holds the desired result of standard deviation.

When I remove Sample column from my report I should get this result in standard deviation cell.

Appreciate your help.

Thanks.