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
Cumulate on future period
Cumulate on future period
- Attachments
-
- Test.xlsx
- (16.89 KiB) Downloaded 155 times
-
- Super Administrator
- Posts: 4590
- Joined: Wed Mar 05, 2003 3:10 am
Re: Cumulate on future period
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.
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.
Advice to posters seeking help (it really helps us to help you)
http://www.ventanasystems.co.uk/forum/v ... f=2&t=4391
Units are important!
http://www.bbc.co.uk/news/magazine-27509559
http://www.ventanasystems.co.uk/forum/v ... f=2&t=4391
Units are important!
http://www.bbc.co.uk/news/magazine-27509559
Re: Cumulate on future period
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.
/*
Advice to posters (it really helps us to help you)
http://www.ventanasystems.co.uk/forum/v ... f=2&t=4391
Blog: http://blog.metasd.com
Model library: http://models.metasd.com
Bookmarks: http://delicious.com/tomfid/SystemDynamics
*/
Advice to posters (it really helps us to help you)
http://www.ventanasystems.co.uk/forum/v ... f=2&t=4391
Blog: http://blog.metasd.com
Model library: http://models.metasd.com
Bookmarks: http://delicious.com/tomfid/SystemDynamics
*/