Hints for running large models

RunGTAP imposes no limit on the size of your model. If your PC has enough memory you can have as many regions or commodities as you like. However, the following considerations apply:

For more than 10 regions or commodities you may need an additional special GEMPACK licence.

If you double the number of regions and commodities, solution time and memory requirements will increase by much more than double.

Use the Tools..Options menu command to switch off the calculation of GE elasticities.

While the model is being solved a small window with a spinning globe appears. If you want to use the PC for other tasks during the simulation, you must click the Hide button underneath the spinning globe. RunGTAP will be minimized to the task bar, but will pop up again automatically when the simulation is completed. Meanwhile you should be able to perform other small tasks, such as reading your email. However, other programs may seem very slow, as the bulk of the PCs resources are devoted to the GEMPACK computation.

Windows will attempt to use virtual memory if your PC lacks suffficient physical memory for the jobs you are running. This can cause GEMPACK jobs to run VERY slowly. A symptom of the problem is constant hard disk activity, as data is paged from hard disk to RAM and back again. Fix the problem by installing more RAM (eg, a gigabyte) in your machine.

URL of this topic: www.copsmodels.com/webhelp/rungtap/hc_hints.htm

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