HELP (Программа GPSS), страница 2

Although installed manuals will be accessible from the Start Menu, you can access manuals from the CD with a browser even if they are not installed. Not only that, the Reference Manual is available in all installations in the form of online Help. Pressing the l key or using the Help Menu of the Main Window will always open a window into the Reference Manual.

CLICK ON Next

If you are performing a Custom Installation, you will see the Component Selection Window, which allows you to select the components to be installed. Do so, and Click on Next to proceed.

Figure 2—6. GPSS World Setup Window 6

Setup Window 6 lets you select a program group in your start menu for placement of the GPSS World menu command. A default is provided. When it is correct,

CLICK ON Next

Figure 2—7. GPSS World Setup Window 7

Setup Window 7 summarizes the choices you have made and allows you to go back to previous windows in case you want to make any last minute changes. When you are ready to finish up the installation,

CLICK ON Next

Now you will see a short series of message boxes giving status as the GPSS World files are being copied onto your computer. Then the last installation window appears.

Figure 2—8. GPSS World Setup Window 8

Setup Window 8 is the last of the installation windows. It allows you to immediately invoke GPSS World after the installation completes. You can use this to begin work in GPSS World now, or you can always do so at a later time by using your Start menu.

If this is a new installation of the Commercial Version of GPSS World, you will need to register the software before you can begin working with models. Now is a good time to get that step out of the way. To perform the registration step go ahead and check the box which invokes the GPSS World program.

Then,

CLICK ON Finish

2.1.7. Software Registration

If youare using the Student Version of GPSS World, skip on to Section 2.2, The GPSS World Environment. Student users do not need to register. Other users must acquire a valid numeric key to unlock the software, if they have not already done so. If you have already registered the software but in a different directory, and your key is valid for the newly installed version, you can avoid this step by copying the old gpssw.key and gpssw.rgs files into the new "GPSS World Commercial Version" directory, also known as "the Module Directory".

Begin the Registration process by starting GPSS World. You can select from the Start / Programs menu. After GPSS World begins, if you do not see the Registration Window, below, you can open it yourself from the GPSS World Main Menu. To do so,

SELECT File / Register Software

Figure 2—9. The GPSS World Registration Window

The purpose of the Registration Window is to create an encrypted message you can send to Minuteman Software in order to obtain a numeric user key. If your method of payment is by credit card, this information is safely inserted into the encrypted message.

The Registration Window gives you the option of having GPSS World send its own registration message by email, or of placing the whole message on the clipboard so you can use your own mailing procedure. In either case you should send the registration ciphertext to registration@minutmensoftware.com. If your registration information and payment are in order, your numeric key will be sent via email to the address you entered into the Registration Window.

Once you have successfully generated a Registration Message you should immediately exit from the GPSS World Environment.

SELECT File / Exit

The next time you start GPSS World you will be given an opportunity to enter the 16 digit numerickey you received after you sent the software registration message.

Figure 2—10. The GPSS World Key Entry Window

Enter you numeric key and

CLICK OK

Normally, this is the only time you will have to deal with a numeric key, unless you install the software on another computer, drastically modify your hardware configuration, or upgrade to a new Version of GPSS World with additional features. Software updates and bug fixes will not require a new key.

Next appears the Notices Reminder Window.

Figure 2—11. The Notices Reminder Window

This Window appears when a long period has elapsed since you downloaded notices from the Minuteman Software Web site. If you click Download, GPSS World will take you to the Internet page where you can download the current notices. Actually, you can download notices any time you like by

SELECT File / Internet / Download Notices

When you download notices, you are given the choice of where to put them. You should place the gpssw.ntc file into the module directory where you installed the GPSS World executables. Be sure you are replacing an existing file named gpssw.ntc.

In any case, the Notices window itself appears with current information on updates, and other useful information.

Figure 2—12. The GPSS World Notices Window

That ends the preliminaries. When you close the Notices Window you should see a fully operational GPSS World Main Window,

2.2. The GPSS World Environment

We now begin a discussion of the manner in which you can control your new simulation environment.

2.2.1. The Main Window

The GPSSWorld simulation environment is the collection of all the actions available to you when you open a Session. Everything is controlled from the GPSS World Main Window, an example of which is shown next.

Figure 2_13. The GPSS World Main Window

The Main Window has several components. The Title Bar is at the very top. Below that is the Menu, and below that the Toolbar (which can be hidden by toggling the View / Toolbar menu command). Most of the action occurs in the large empty client area.

At the very bottom of the Main Window is a Status Line that is divided into three parts. The left pane of the Status Line shows Command Prompts that give you more information on the menu items you are about to use. The middle pane of the Status Line shows status and error messages send from the GPSS World Objects you are interacting with. Finally, there is a small pane at the right side of the Status Line that is used to display the changing System Clock of running simulations. You can turn this on or off for each Simulation Object by using the View / Show Clock menu command.

2.2.2. A Quick Overview

Using the menu of the Main Window, you can create and manipulate the Objects of GPSS World: Model, Simulation, Report, and Text Objects. Each of these will have one or more views that can be opened within the GPSS World Main Window.

A typical project begins with the creation and modification of a Model Object. A Model is just a list of Model Statements, defined in Chapters 6, 7, and 8. After the Model is composed the next step is to create a Simulation Object. Each time you select Command / Create Simulation or Command / Retranslate from the Main Window's Menu, GPSS World Translates the Model Statements into a runnable Simulation Object. If errors need to be corrected, a single keystroke (representing Search / Next Error) can cycle through the circular error list, setting the cursor in the Text View of the Model, just before each error.

Once a Simulation Object is successfully Created, you can send any Model Statement to it to change the structure or state of the simulation. Normally, you will send Commands, such as START, but you can redefine entities or PLUS Procedures, as well.

You can send Model Statements to existing Simulation Objects using one of several methods.

First, some of the most common commands are listed in the Command menu of the Main Window. Most have keyboard accelerators as well.

Second, the Custom Command dialog is invoked through Command / Custom in the Main Window's menu. Here you can type any Model Statement -- even a PLUS Procedure -- and send it to an existing Simulation Object.

Third, you can load the set of function keys with you own choice of Commands. This is done through the Edit / Settings menu item in the Main Window. Thereafter, pressing the function key sends the Command to the currently selected Simulation Object.

Complex PLUS Procedures and lengthy Command lists can be sent using an INCLUDE Statement associated with a previously created Text Object. You can enter INCLUDE as a custom command ( Command / Custom ) or load it into a function key. After an INCLUDE Statement is loaded into a function key ( Edit / Settings ), a single keystroke sends the whole lot to the Simulation Object for processing.

During the debugging phase of your project, be sure to make use of all the visualization tools at your disposal. There are 10 dynamic windows and 7 snapshot windows that let you view the running simulation. Most require no effort on your part except to open them. Some, like the Blocks Window, add point and click debugging facilities for manipulating stop conditions and for controlling the advance of the simulation during debugging.

A new PLUS Trace feature can be turned on in the Settings Notebook. It will place a description of each PLUS Procedure invocation in your Journal Window. Here's a useful tip: If you define a PLUS Procedure that takes arguments but does nothing, you can place invocations of it anywhere in your PLUS code to evaluate and trace your own User Variables -- both Global and Temporary.

Among the dynamic windows are the Plot and Expression Windows which allow you to visualize the evaluation of any PLUS expression as it changes dynamically. The Tables Window can also be very enlightening, visualizing the convergence of frequency distributions. In addition, there are seven snapshot windows that present detailed state information at some instant within the simulation.

GPSS World is strong in the extensiveness of its Standard Reports. Unless you choose otherwise, when a Simulation Object completes a simulation (i.e. the Termination Count reaches zero), it creates a Report Object containing a Standard Report describing the final state of the simulation. You can modify the content of Standard Reports by editing the Settings of the Simulation Object. Interim reports can often be used effectively during the debugging/testing process. While interacting with a Simulation Object you can use the REPORT Command to create a Report Object describing all internal GPSS Entities.

You can extract just about any information you desire from a simulation by using Data Streams. These are associated with a set of GPSS Blocks and PLUS library procedures (OPEN, CLOSE, READ, WRITE, SEEK) that allow you to trace and collect derived information from the simulation and write them to plain text files. Such traces can be used to drive photo-realistic animations, as well. Within GPSS World, text files used in association with Data Streams are represented as Text Objects. The new Call PLUS procedures provide direct online access to external programs such as ad-hoc animators.

After the Model is thoroughly tested, it is time to define an Experiment to quantify results and test their statistical significance. GPSS World excels in this regard. Its built-in programming language, PLUS, supports a special kind of PROCEDURE statement, called, naturally, the EXPERIMENT Statement. Within an experiment, you can run and analyze complex experiments unattended. You can even get an automatic Analysis of Variance of the results. These features are developed in the OneWay.gps Sample Model, and further in Lessons 19 and 20 of the GPSS World Tutorial Manual. Chapter 13 of this manual discusses ANOVA and the Automatic Experiment Generators in depth.

Getting Help

GPSS World provides several Help aids to keep you on track. The most immediate is the Online Help feature. Online Help is available throughout GPSS World. The l Function Key will bring up a Help Panel for the active window or dialog. In additional, if you press the l key when a menu item is highlighted, a context sensitive Help Panel will appear with information pertaining to that menu item. Within the Text View of an object, select a word and press the l key to go to the keyword's description in the GPSS World Language reference section of the Help file. Finally, Online Help can be initiated by a Help button in some dialog boxes.

The Internet offers more help on GPSS World. HTML Online documentation can be found at the Minuteman Software Internet Web site, MinutemanSoftware.com. This site offers many other support options as well. You can get to it by

SELECT File / Internet / GPSS Web Page

in the Main Window's menu.

The MinutemanSoftware.com site contains other useful resources and ways to communicate with other users and consultants. The Student Version of GPSS World can be downloaded from the Web site free of charge. The official documentation of GPSS World includes this manual, the GPSS World Reference Manual, and the GPSS World Tutorial Manual. Both are available on the Web site and in hardcopy, as well.

Don't overlook the extensive set of sample models. Many professionals have found that one of the fastest ways to acquire simulation skills is to examine the work of others. The sample models in every GPSS World installation include a wide variety of applications of simulation to real-world problems.