Extracting Condensation statements from a STI file

Condensation is a vital tool to reduce the numbers of variables and equations, so that larger models can be solved quickly. You can OMIT, SUBSTITUTE or BACKSOLVE variables to condense your model.

The traditional method has been to list the omit, substitute and backsolve actions in a STI (stored input) file. However,  condensation actions can instead be included on the TAB file. For example, STI file lines:

o

a1

a1oct

! blank line showing end of omits

s

p1

E_Price1

b

p1lab

E_p1lab

could be replaced by these 3 lines at the end of the TAB file:

OMIT a1 a1oct a1mar a1_s a2 a2mar ;

SUBSTITUTE p1 USING E_Price1 ;

BACKSOLVE p1lab USING E_p1lab ;

This more modern alternative will often be clearer and more maintainable — in many cases a STI file will no longer be needed.

Inertia rules, however, and many older models continue to use a STI file to specify condensation.

Under the Tools menu, the command Create in-TAB condensation from STI is designed to convert legacy STI files to a sequence of new-style condensation statements which you can simply paste into the bottom of your TAB file.

The command is only enabled if you are looking at a file suffixed STI.

STI file errors may be poorly diagnosed -- you should check that the STI file works properly before extracting from it.

URL of this topic: www.copsmodels.com/webhelp/tabmate/hc_condfromsti.htm

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