How to Use AMPL in VSCode

This post is a guide to help you set up Visual Studio Code (VSCode) to write and run AMPL code if you cannot use the AMPL IDE on your computer.

• Install VSCode
• Install AMPL
• Install the AMPL Extensions for VSCode
• Configure the AMPL Path
• Write and Run AMPL Code

Install VSCode

Visual Studio Code is a free source code editor developed by Microsoft. You can download and install it from the official website.

Install AMPL

AMPL (A Mathematical Programming Language) is a modeling language for mathematical programming. Download and install it from the official website. If you are a student from Les Mines Nancy, use the link available on arche to create an account with your university email (@etud.univ-lorraine.fr) for a free student license.

Install the AMPL Extensions for VSCode

To install the AMPL extensions in VSCode, follow these steps (see the image below):

1. Click the Extensions icon on the left side of the VSCode window.
2. Search for “AMPL” in the search bar.
3. Install the following extensions by clicking Install:
   • AMPL by Michael Sundvick – Adds a button to run AMPL files.
   • AMPL for VSCode by Johan Cho – Provides syntax highlighting and definitions on hover.

Configure the AMPL Path

To use AMPL in VSCode, configure the path to the AMPL executable:

• Open the settings in VSCode using:
  • Ctrl + , (keyboard shortcut), or
  • File > Preferences > Settings, or
  • Click the gear icon in the bottom-left corner and select Settings. (1 and 2 in the image below)
• Search for “AMPL” in the settings search bar. (3 in the image below)
• Set the path to the AMPL executable in the Ampl: Executable Path field.
  Example paths:
  • C:\ampl\ampl.exe (Windows)
  • /home/YOUR_PATH/amplide.linux64/ampl.linux-intel64/ampl (Linux)
• Optionally, check the box Ampl: Use Relative Path to use a relative path.

Write and Run AMPL Code

Follow these steps to write and run AMPL code (if you are a student from Les Mines Nancy):

1. Download the archives “AMPL examples” (under the pdf lesson on AMPL) and “AMPL data files” (in “Solutions to the exercises” section) from arche.
2. Extract the archives (right-click and select Extract Here) and move all the files to the same folder (in a repertory called ampl_exercises for example).
3. Open the folder in VSCode:
   • Use the menu: File > Open Folder.
   • Alternatively, in the terminal, navigate to the folder and type code .
4. View the folder contents in the Explorer panel on the left side of the VSCode window.
5. Open the files farmer.run and farmer.mod.
6. Arrange the tabs to view the code side by side if needed.
7. In the top-right corner of the farmer.run file, click the button AMPL: Include File to run the file with AMPL.
8. A terminal will open, displaying the results of the execution.

If you are not a student from Les Mines Nancy, you can follow this steps :

1. Create a folder and open it in VSCode.

2. Create a new file prod0.mod and write the following code (from the AMPL book):

   # Variables
   var XB;
   var XC;
      
   # Objective Function
   maximize Profit: 25 *XB + 30* XC;
      
   # Constraints
   subject to Time: (1/200) *XB + (1/140)* XC <= 40;
   subject to B_limit: 0 <= XB <= 6000;
   subject to C_limit: 0 <= XC <= 4000;
   

3. Create a new file prod0.run and write the following code:

   reset;
      
   model prod0.mod;
      
   option solver gurobi;
   solve;
      
   display XB, XC;
   

4. Click the button AMPL: Include File in the top-right corner of the prod0.run file to run the file with AMPL.

5. A terminal will open, displaying the results of the execution :

    Gurobi 12.0.0: optimal solution; objective 192000
    1 simplex iteration
    XB = 6000
    XC = 1400