How to Read Results in a .LST File
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1. What is the Listing File?
Every time a GAMS model is run, it
generates an output file called the listing file. The file has the suffix “.lst” and the file
name is the same as that of the model.
For example, when you run the model “UNI-CGE10.GMS,” the listing file
will be named “UNI-CGE10.lst”.
2. Where is the .LST File?
Figure 1. Setting for Viewing the .LST file
Now run the UNI-CGE model – the UNI-CGE.gms file. Click on that file name in the menu bar, then click on the green arrow, circled in green in Figure 2. As the model solves, a process log opens on the right side of the screen. The log tells you whether the model has solved successfully. In this example the model solves successfully, as reported in the line of code circled in red. If the model fails to solve, the process log will identify the errors you must correct.
When the
model has finished running, the .gms file in the viewing frame will be
automatically replaced by the .lst file.
You can now toggle between the .gms model code and the .lst file. You
can leave the .lst file open because it will be overwritten with new model
results every time you run the .GMS model.
Figure 2. GAMS model,
process file and .lst file
3. Locate and View Results in .LST File
The .lst file prints any item for which there is a “display” command in the GAMS model. Figure 3 shows an example of a command in the GAMS file to display the elasticity “ESUBQ,” the domestic-import substitution elasticity.
Figure 3. GAMS code to
command a display in the .lst file
You can also define new elements that are not in the GAMS model and command that they be displayed in the .lst file. As an example, we create and define a parameter named “NewElementc,a” the cost of each commodity C used as an intermediate input by production activity A. We define NewElement as price times quantity (PQc,a * QINTCAc,a). After defining the element, we add the command to display it.
After running the model, find an element that is displayed in the .lst file by typing the command: Control + F. This will open a search box, in which you input the name of the element you want to find. In Figure 4, we search for ESUBQ. If there are many instances of ESUBQ in the .lst file that you want to view, you can click on the “Find All” option. You can also search for each instance by clicking on the forward and backward buttons.
Figure 4. Search for an
element in the .lst file
The search
will take you to the element that you commanded GAMS to display in the .lst
file. In Figure 5, both ESUBQ and
NewElement parameters are displayed in the .lst file.
Figure 5. Elements are
displayed in the .lst file
4. Key Results in the LST File
The UNI-CGE model code includes commands to organize key results into tables and display them. You can search for these tables and variables in the .lst file after you carry out a model experiment. Table 1 provides a summary of the tables and their contents.
Content |
|
Res_QCOM_pc |
% change in commodity quantities (production, consumption, trade) |
Res_PCOM_pc |
% change in commodity prices |
Res_PROD_pc |
% change in production quantity and value added |
Res_SCAL_pc |
% change in scalar values (macro variables) |
RGTAPtab_pc |
% change in real GDP |
FACT_pc |
% change in factor results |
QF_pc |
% change in factor quantities by factor and activity |
WFA_pc |
% change in factor price distortion by factor and activity |
CTAXR_B |
Base commodity tax rates (sales, export and import taxes) |
CTAXR_L |
Updated commodity tax rates (sales, export and import taxes) |
ATAXR_B |
Base activity output tax rates |
ATAXR_L |
Updated activity output tax rates |
YTAXR_B |
Base income tax rate |
YTAXR_L |
Updated income tax rate |
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