Cumulate on future period

[RemiM]

Hello,

I am building a model to simulate MRP logic. I haven't found any existing model on the web.
For MRP logic, I need to look at "planned requirements" in future periods, and cumulate those over a period of time (Constant).
> ror any period P, I need to cumulate Data(P)+Data(P+1)+...+Data(P+i), where i is a Constant.
The equivalent in excel would be the column F in spreadsheet attached.
I have tried to build a simple model with TIME SHIFT, and CUMULATE, but I failed so far.

Thank you for your help.
Remi

[Administrator]

Is the parameter you are trying to sum external data or a calculation?

If a calculation, then it cannot be done (as the calculation hasn't been made yet). If it's external data, you can use GET DATA AT TIME to get the future value.

[tomfid]

There's no general way to look into the future for non-data variables (that would be "acausal," i.e. no one actually knows the future). However, you can use arrays to create a virtual time dimension for future calculations. Or, in some cases, you can solve for the future trajectory analytically.