Using AMPL Studio

Overview

Overview of AMPL Studio

AMPL Studio Main Window

When you launch AMPL Studio, the Main window appears. All tasks and commands for using AMPL Studio are carried out from this window. Figure 4.1 shows the Main window with three opened files, steel.dat, steel.mod and diet_solution.txt.

AMPL Studio Main Window

If you have a mouse with a wheel between the two buttons, you can use the wheel to scroll up and down.

· Menu Bar provides various menu commands to choose from, such as Save in the File menu, and to display dialog boxes to perform various tasks. Certain menu commands, followed by a ▶ image on their right hand side, have their own sub-menu commands.

e.g.

AMPL Studio Sub Menus

The Add To Project Command menu has five sub command menus, Model, Data, Table Definition, Script and Query Command.

· Tool Bar provides frequently used command buttons.

· Execution Tool Bar buttons is used for executing the Models, Projects and Scripts.

· Work Space contains a notebook with three pages, FileView, ModelView and SolverView.

FileView displays project tree structures containing all the files related to each project. The project files are arranged under Model, Data, Database and Script containers. It also displays stand-alone models and scripts.

ModelView displays the various model components, such as Parameters, Sets, Variables, Constraints, Problems and Objectives in separate containers for easy access. Any particular information can be displayed by clicking on it and diverse parts of the solution.

SolverView is the sane as ModelView, with the difference that it displays what solver see after presolve.

· Editing Area displays opened model, data, database, script, and Solution files. New files can be created and any existing files can be edited in this area. You can open more than one file in this space. The opened files are displayed in separate panels with the file name appearing in the title bar.

· Output Notebook has five tabs to display AMPL Console Messages, Debug Information, Solution Files, Timing and Memory Information, and Display all other information. By default AMPL studio will display the most appropriate window for the user action, but the user can switch to another window by clicking on the tab at the bottom of the Output Notebook.

· Status Bar displays messages concerning the execution status of AMPL Studio.

· Line and Column displays line and column number of the cursor location in the active document in the editing area.

In the graphic interface Menu Bar, Tool Bar, Execution Tool Bar, Work Space and Output Area are dockable:

A dockable element can be detached from, or floated in its own frame window or it can be attached to, or docked at any side of its parent window.

Menu Bar Commands

File Menu

Edit Menu

View Menu

Project Menu

Solver Menu

Build Menu

Tools Menu

Stochastic Menu

Window Menu

Help Menu

Overview of Commands in the Menu Bar

Some of the menu items have a keyboard shortcut, indicated on the right-hand column of the menu. For example, Keyword Save has the shortcut Ctrl + S, which means that you can save the active document by clicking the Ctrl key and the S key at the same time.

The following tables (Table 4.1 - Table 4.10) list the command found in the menus and provide a description of each command.

Command

Description

New

Creates a new file.

Open

Opens a file.

Close

Closes an opened document.

New Workspace

Creates a new workspace

Open Workspace

Opens an existing workspace

Save Workspace

Saves the current workspace

Close Workspace

Closes the current workspace

Save

Saves the current edited file.

Save As

Saves the current edited file with a new name.

Save All

Saves all the open files.

Print

Prints a document.

Print Setup

Selects a printer and printer connection.

Send Mail

Sends the active document through electronic mail.

Recent File

Displays a list of previously opened documents.

Recent Workspaces

Displays a list of previously opened workspaces

Exit

Exits AMPL Studio.

File Menu Command descriptions

Command

Description

Undo

Undoes an unlimited number of nested actions in the current editor.

Redo

Redoes previously undone actions in the current editor (unlimited).

Cut

Deletes the selected text from the editor and puts it in the clipboard.

Copy

Copies the selected text, from the editor or output window, to the clipboard.

Paste

Pastes from the clipboard to the current editor.

Send

Email the opened file.

Select All

Selects the entire content of the current editor.

Find

Displays the Find dialog box for specifying search criteria.

Find Next

Finds the next occurrence of the text displayed in the Find box.

Find Previous

Finds the previous occurrence of the text displayed in the Find box.

Replace

Displays the Replace dialog box for specifying search criteria and replacing specified strings.

Read Only

Set the active document as read only file.

Bookmarks

Bookmark a script line.

Bookmarks (#)

Bookmark a line with the number.

Goto Bookmark (#)

Go to the bookmark number.

Edit Menu Command descriptions

Command

Description

Status Bar

Displays the Status Bar.

Workspace

Displays the Workspace.

Output

Displays the Output Notebook.

Script Bar

Display the Script Execution Toolbar.

Full Screen

Displays the active file in full screen mode.

Prompt Command

AMPL command line

View Menu Command descriptions

Command

Description

Set Active Project

When several projects are open, remembers the project selected in the Project Tree as the active one.

Add To Project

To insert a model, data, database or script files to the project.

Ampl Settings

To change the AMPL settings.

Insert New Project

To insert a new project into the opened workspace.

Insert Existing Project

To insert an existing project into the opened workspace.

Project Menu Command descriptions

Command

Description

Minos

To select the Minos Solver as a default Solver.

CPLEX

To select the CPLEX Solver as a default Solver.

FortMP

To select the FortMP Solver as a default Solver.

CPLEX Settings

To Change the CPLEX Solver settings.

FortMP Settings

To Change the FortMP Solver settings.

Solver Menu Command descriptions

Command

Description

Build Model

To build the model.

Build Data

To build the data

Rebuild All

To build the all models and data

Clean

To clean all read information from the memory.

Solve Problem

Solve the read problem.

Start Debug

Start to debug the script.

Save Problem

Save the current problem.

Save Solution

Save the solution.

Load Solution

Load the solution.

Build Menu Command descriptions

Command

Description

Customize

[Future Functionality]

Options

Displays the Default Options dialog box that allows changing the AMPL Studio options.

Tool Menu Command descriptions

Command

Description

Check Syntax

This command performs the syntax check of a model written using SAMPL’ s extended AMPL keywords for stochastic programming.

Solve SPInE

The current model is parsed, and then solved using SAMPL’ s solver. The solver settings, including the solution types, can be modified using the Solver options… command.

Generate

An SMPS representation of the current model instance is generated using this command. By default, SAMPL/SPInE generates Windows/DOS text files. This may not compatible with other UNIX based solvers. The advanced option UnixOutput described in the SP Generator options (SPG) section enables the user to change the output text format to UNIX.

Solve Current

This command solves the latest SMPS instance generated for the current model. If such instance is not available, then this command is equivalent to the Solve SAMPL command.

Generate Options

This command displays the Generator Options dialog box. Settings for the generator of SMPS instances can be modified using this command.

Solver Options

This command displays the Solver Options dialog box. Settings for SAMPL/SPInE’ s solver can be modified using this command.

Report Options

This command displays the Reporting Options dialog box. This dialog box enables the users to change the way SAMPL/SPInE exports the solution vectors obtained from the solver.

View Options List

This command displays the current settings of the SAMPL/SPInE system. Advanced users can run this command in order to manually edit the advanced options provided by SAMPL/SPInE.

Stochastic Menu Command descriptions

Command

Description

New Window

New window for the active document

Cascade

Displays overlapping panels in the editing area.

Tile

Displays panels in the editing area horizontally.

Arrange Icons

To arrange icons.

Close All

Closes all the windows in the Editing Area

Window Menu Command descriptions

Command

Description

Help Topics

To view AMPL Studio Help Topics

Online

Opens the AMPL Online help window.

www.ampl.com

Go to AMPL web site

About Ampl Studio

Indicates the version of AMPL Studio, the OptiRisk-Systems products used by AMPL Studio, and contains copyright information.

Help Menu Command descriptions

Tool Bar Buttons

The following buttons appear in the tool bar:

Button

Description

To create a new blank document

To open an existing document. AMPL Studio displays an Open File dialog box requesting the file name you wish to open. The file is then displayed in the editing area.

To open an existing Workspace. AMPL Studio displays an Open File dialog box requesting the workspace you wish to open. The workspace and their related projects and files will be displayed in the workspace window.

To save the active document in editing area.

To save all the modified files.

To cut the selection and put it on the clipboard.

To copy the selection and put it on the clipboard.

To insert clipboard contents.

To undo the last action.

To redo the previously undone action.

To show or hide the workspace window.

To show or hide the output window.

To manage the currently open windows.

To find the specified text.

To Repeat the last find text action (down).

To Repeat the last find text action (up).

To replace specific text with different text.

To display the active file in full screen mode.

Toolbar Buttons and Descriptions

Execution and Debugging Tool Bar Buttons

The following buttons appear in the tool bar:

Button

Description

To build a model.

To build a data.

To solve a problem.

To reset the project.

To run script.

Go.

To step out of a loop in a script and avoid going through all the iterations.

To go to the next solution of the model or project, or to the next instruction in stepping mode or to the next choice point in ‘stop at choice point’ mode.

Continue running the script without stepping.

Set a selected entity (variable | parameter) to watch during the stepping stage

To set breakpoints/Marker in the AMPL model or script file.

To go to the previous breakpoint/marker

To go to the next breakpoint/marker

Clear all breakpoints/Markers markers

Execution Toolbar Buttons and Descriptions

Workspace

AMPL Studio Workspace is divided into three sub windows, FileView, ModelView, and SolverView. The user can switch between these windows by clicking on the required tab at the bottom of the Workspace.

The Fileview displays the Workspace Files in the Tree structure.

Workspace File View

The ModelView displays the Model Parameters, Sets, Variables, Constraints, Problems and Objectives information, which becomes available after the models and their associated data files are built.

Workspace Model View

The SolverView displays Solved Model information, which becomes available after the model is solved.

Workspace Solver View

Editing Area

AMPL Studio allows the user to open many files into the editing area. One can edit existing files or create new files in the Editable Area using the AMPL Studio’s text editor. The user can edit multiple files by switching between the Editor Windows. Also the user can Resize, Minimise, Maximise and close any window.

Console

AMPL studio outputs are divided into Console, Debug, Solution, Timing and Memory, and Display windows. AMPL Studio automatically displays the most appropriate window for the user action. The user can switch between these windows by clicking on the required tab at the bottom of the Output Notebook.

The AMPL console output is displayed in the Console Window.

Output Console Window

The Debug results are displayed in the Debug Window.

Output Debug Window

The Solution files generated by the solvers will be displayed in the Solution Window.

Output Solutions Window

The processing Time and Memory usage of AMPL studio are displayed in the Timing/Memory Window.

Output Timing and Memory Window

All other AMPL Studio output will be displayed in the Display Window.

Output Display Window

AMPL Studio – Basics

This section describes several basic concepts to consider when using AMPL Studio.

File Types

· Models

Model files contain AMPL statements. A stand-alone model is a model that can be executed in AMPL Studio without any additional requirements.

· Data files

Large problems are better organized by separating the model of the problem from the instance data. The instance data is stored in a data file (or in several data files).

· Projects

AMPL Studio uses the concept of a project to associate a model file with a number of data files. The model file declares the data but does not initialise it. The data files contain the initialisation of each data item declared in the model. The project file then organizes all the related model and data files. A project provides a convenient way to maintain the relationship between related files and runtime options for the environment.

· Scripts

Script files contain AMPL Script, a script language for AMPL. A script handles different models with their data. The models and data files are associated in the script itself.

The following naming conventions are used to indicate these different files:

File Extension	Description
`.mod`	Used for files containing models.
`.dat`	Used for files containing data instances.
`.sa1 or .run`	Used for scripts written in AMPL Script.
`.ini`	Used for project files.
`.wampl`	Used for Workspace files

File extensions and descriptions

In this Chapter and in Chapter 6 we will see how to create project files, associate model and data files with the project, and then find the solution to the problem using the project file.

Working with AMPL Studio

The model and data files used in the examples in this manual are distributed with the product. This way the reader will not have to create these files from scratch, but just open them once AMPL Studio is launched.

Opening an Existing Workspace

To open existing workspaces do the following

Step 1: Choose the Open Workspace from the File Menu.

Open Workspace from the File Menu

Step 2: AMPL Studio then displays a standard Open File dialog box in order to select the file that corresponds to the workspace we want to open.

Choosing AMPL Workspace File

Select from the directory: AMPL Studio Installed Directory/Examples/netlib and choose the workspace name e-g: largeworkspace.wampl and click on the Open button.

If you have recently used the workspace, you can alternatively select it from the Recent Files submenu.

The AMPL studio will open the workspace and displays it in the workspace window as shown below.

Opened Workspace in AMPL Studio

Creating a New Workspace

To create new workspaces do the following

Step 1: Choose the New Workspace from the File Menu.

File Menu

New Workspace from the File Menu

Step 2: AMPL Studio then displays a New Workspace dialog box in order to enter the Workspace name and the Folder where the workspace will be created.

New Workspace Dialog box

Enter the workspace name as MyFirstAMPLWorkspace and choose your preferred folder by clicking on the button.

AMPL studio will open the new empty workspace and display it in the workspace window as shown below.

New Workspace in AMPL Studio

Inserting an Existing Project into the Workspace

To insert an existing project into the current workspace do the following

Step 1: Choose the Insert Existing Project Menu from the Project Menu.

Project Menu

Insert Existing Project Menu from the Project Menu

Step 2: AMPL Studio then displays a standard Open File dialog box to select the file that corresponds to the project we want to open.

Choosing AMPL Project File

Select from the directory: AMPL Studio Installed Directory/bin and choose the project file steel.ini and click on the Open button.

The AMPL studio will insert the project into the workspace and display it in the workspace window as below.

Inserted Project in the Workspace

The file can be viewed in the Editing area by clicking on the file in the workspace. For example, clicking on the steel.mod will display the steel.mod in the Editing Area.

Viewing the Model file from the Inserted Project

Adding a New Project into the Workspace

To insert a new project into a workspace do the following

Step 1: Choose the Insert New Project Menu from the Project Menu.

Project Menu

Insert New Project Menu from the Project Menu

Step 2: AMPL Studio then displays an Open New Project dialog box in order to specify the new project name and the directory where the project will be created.

Insert New Project Dialog Box

Enter the project name as MyFirstAMPLProject and choose your preferred folder by clicking on the button.

Also you have the option to add the model and data template files by choosing the Add template check box. Type the model and data template files as MYFirstAMPLModel.mod and MyFirstAMPLData.dat.

Click the OK button to add a new project to the workspace

The AMPL studio will insert the project into the workspace and display it in the workspace window as shown below.

New Project View in the AMPL Studio

You can now start to write a new model and data files. Don’t worry about writing the model and Data file at this stage. Chapter 5 and 6 will cover this in more detail.

Activating the Project

As you can see the steel project was active () before you add your new project. When you add the new project AMPL studio assumes the new project is going to be your active project and displays it as below

New Project Active AMPL Studio

To set the steel project back to active project, do the following.

Step 1: Click on the Steel Project Node.

Step 2: Right clicking the mouse will display the following menu.

Choosing the Set as Active Project Menu

AMPL Studio will change the steel project back to active project as below.

Workspace with steel project as active

You can also activate the steel project by selecting the Set Active Project menu from the Project Menu

Selecting the Solver

By default AMPL studio provide three solvers, Minos, CPLEX, and FortMP. You can choose your preferred solver from one of these solvers. In order to choose FortMP as your default Solver select the FortMP Menu from the Solver Menu.

Solver Menu

Selecting the FortMP Solver as the default solver

AMPL Studio also has the facility to use the solvers provided at the NEOS server. To use one of those solver choose the solver from Neos Solvers dropdown

Selecting the Neos Solver

Setting the Solver Options

CPLEX and FortMP solvers have their own solver settings. You can change these setting accordingly to suite your project needs. In order to change the FortMP Solver settings choose the FortMP Settings menu from the Solver Menu.

Solver Menu

Selecting the FortMP Solver Settings

AMPL Studio then displays the following FortMP Solver setting dialog box for your selection.

FortMP Solver Settings Dialog Box

FortMP Solver settings are divided into Basic, Simplex, IPM Control, Tolerance, Maximum Limits, Input/Output, Log Control, MIP Control and Advanced Control. The detail of these can be found in the FortMP Manual.

CPLEX Solver setting can be done in a similar way.

Some additional options may exist for the solvers, which are not displayed in the solver settings menu. These options can be added in the solver options file. To include the solver options file, first go to Options menu and tick Insert file options in project for additional solver options. A solver options file is then included in the workspace as displayed on the left hand side of AMPL Studio.

Selecting the file option for additional solver settings.

Modifying solver settings in solver options file.

Build the Model

In order to solve the problem the model and associated data files need to be built. Do the following steps to build the steel project model and data files.

Step 1: Click on the steel.mod file.

Selecting the steel.mod file in the Workspace

Step 2: Click on the button on the Execution Toolbar to Build the Model.

The AMPL Studio reads the model and displays the following Console Message.

AMPL Console message for reading steel.mod file

Step 3: Click on the steel.dat file.

Selecting the steel.dat file in the Workspace

Step 4: Click on the button on the Execution Toolbar to Build the Data.

The AMPL Studio reads the model and displays the following Console Message.

AMPL Console message for reading steel.mod and steel.dat file

Solving the Problem

Now the Model and Data files are read and the Solver is selected. In order to solve the problem do the following steps.

Step 1: Click on the button on the Execution Toolbar to solve the problem.

You can also select the Solve Problem Menu from the Build Menu.

The AMPL Studio will solve the steel problem using FortMP Solver and display the solution file in the editing area.

AMPL Studio Solver Console message and Solution Display

Viewing Results

The user can view various parts of the model and the solution from the Workspace and their information will be displayed on the display window as shown below.

Step 1: Click on the ModelView tab on the Workspace.

Step 2: Expand the Parameters node and Double Click on the rate Parameters.

Choosing the rate Parameter for Viewing

The AMPL Studio Display Window displays the rate parameters as below.

Displaying the rate Parameter

Step 3: Now Expand the Variable node and Double Click on the Make Variable.

The AMPL Studio Display Window displays the Make variable value as shown below.

Displaying the Make Variable

Solving the project with the Script

In the previous sections you have solved the steel project. During the Solution process you have gone through a number of steps like Build Model, Build Data, Selecting the Solver, etc., to generate the solution. This process can be automated by creating a script file.

The following steel.sa1 script file was written to automate what we have done during the previous section. In this case we use CPLEX solver to solve the steel problem.

Writing Script File

Clicking on the button will execute all the AMPL Statements in the script file and display the results.

Setting the AMPL Studio Options

AMPL Studio has various options for you to choose from. In order to update the AMPL studio options choose the Options Menu from the Tools Menu.

Tools Menu

Choosing AMPL Studio Options

AMPL Studio then displays an AMPL Studio options in the following dialog box for your selection.

AMPL Studio Options Dialog Box

AMPL Studio options are divided into Solve Solution, Save Options, Workspace and Expand Constraints categories.

Using online help

Online help can be accessed from the Help Menu. You need an Internet connection to access www.ampl.com Menu from Help Menu.

Terminating the AMPL Studio

Selecting the Exit menu from the File Menu will terminate the AMPL Studio session.