How to create calculations in the DMR model

[Cognosnewbie26]

Hello,
I wanted to create a calculation in the DMR model which is basically calculating the variance% of amounts between current year and prior year. For e.g

Amount of CY - Amount of PY
----------------------------------   * 100
Amount CY

How do I achieve this?

[Deep750]

Should be straight forward, create the items in DMR-layer, and base the calculations on these items.

[Cognosnewbie26]

Should be straight forward, create the items in DMR-layer, and base the calculations on these items.

Question is how? Sorry I am still trying to figure out FM.
I have a measure dimension and time dimension. Where should these items go? In Measure dimension? Somebody said I should use tuples.
I am literally struggling with dimensional functions.
Would really appreciate some help.

[Cognosnewbie26]

So for the uninitiated ones like me thought I would post my progress here.
I was able to create a standalone calculation in my DMR layer
using tuples.
I tried adding the same calculation to my Measure Dimension but it does not work why? Can anyone please tell me why and how to make it work?

Note: For some reason I am not able to add my code here