getting :LOOK FORWARD: to look forward ...

[mike]

Given the following equations;

"spreadsheet data 00-03" :=
GET XLS DATA( 'data.050204.xls' , 'vensim' , 'xls_time' , 'xls_named_range '\
)
~ $
~
|


test data LOOK FWD :LOOK FORWARD::=
"spreadsheet data 00-03"
~ $
~ ~ :SUPPLEMENTARY
|


For the above data equations I had expected ‘test data LOOK FWD’ variable to span the entire simulation;
yet it shows up in the Vensim graph as matching the spreadsheet fed data variable and apparently is not
reflecting the ’look forward’ data transformation expected. Am I doing something wrong here or misunderstanding this functionality? This was run on Vensim DSS32 version 5.3a on Wintel PC.
Guidance appreciated.


Regards,
Mike

[Edited on 2-16-2005 by mike]

[mike]

couldn't attach word doc with Vensim graphs to illustrate problem; the spreadsheet data is 4 annual year end data points in a 16 year, monthly time step simulation ; expected :LOOK FORWARD: to show 192 data points where it only replicated the 4 points fed in ?

[Administrator]

Hi Mike,

Can you provide the sample model and source data so we can look at the input and output?

The documentation on it is here.
http://www.vensim.com/documentation/html/22045.htm

Is this how you are expecting it to work?

Tony.

[mike]

attached xls

[mike]

attached model

[Administrator]

>> expected :LOOK FORWARD: to show 192 data points where it only
>> replicated the 4 points fed in ?

This is working exactly as designed. The look forward function will get the next data point it finds in the input stream. And as look forward is a data equation, it will only return data (ie, it will not 'compute' anything).

If you create an variable that is just equal to the look forward one, that should give you what you are expecting.

Tony.

[mike]

THANK YOU; I didn't realize the need for the extra variable assignment.

Regards,

Mike