Computable General Equilibrium Modeling and Its Application in Trade Policy Analysis Lab 1: Basic pr

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Computable General Equilibrium Modeling and Its
Application in Trade Policy Analysis Lab 1
Basic programming in GAMS

• Zhi Wang
• U.S. International Trade Commission
• E-Mail zhi.wang_at_usitc.gov

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Outline

• Use of GAMS IDE (Integrated Development
  Environment)
• Basic Feature of GAMS
• Program examples

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Steps to use IDE

• Create or open an existing file, types of GAMS
  files
• create a new file
• Open an existing file
• Open a model library file
• Prepare program for execution
• Run GAMS code
• open and navigate around the output

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Steps to use IDE

• Open IDE
• Create a project, define a project name and
  location
• The project location determines where all saved
  files are placed and where GAMS looks for files
  when executing
• Define a new project every time you change file
  directory

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Feature of GAMS

• allows modelers to specify models in (nearly)
  standard algebraic notation
• Most of the departures from standard algebra
  are straightforward
• SUM" represents the summation operator,
  SUM(i,... means sum over the index i, while
  SUM((i,j),... means some over both i and j.
• "PROD" represents the product operator
• Parameters are treated as constants in the model
  variables are free to vary endogenously

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Feature of GAMS

• Sets Declaration and Assignment of elements
• Data Parameters, Tables, Scalar Declaration and
  Assignment of values
• Variables Declaration and Assignment of type
• Equations Declaration and definition