HELP (Программа GPSS), страница 3

The Main Menu

Mostof the action begins at the menu of the Main Window. Each of the top-level menus

File Edit Search View Window Help

have submenu items, most of which are enabled only when appropriate. To help guide your actions, GPSS World disables irrelevant menu commands. When disabled, menu commands are gray and cannot be activated. When there is ambiguity as to which Object is to receive the Command, you will have to select one of the object's windows with the mouse or keyboard in order to activate the related menu commands.

Now, let's look at each top level menu.

The File Menu

The leftmost menu is the File Menu. It is used to open and save Objects, print views of Objects, access the Internet to download notices and Internet Web pages, and to register the software for users of the Commercial Version.

The Edit Menu

The top items in the Edit Menu are for working with text. All GPSS World Objects have a Text View that can be modified using these menu commands. Undo is a "one-level backup" facility for removing the effects of the last Text View interaction. Cut, Copy and Paste move selections to and from the Windows clipboard. Insert Line and Delete Line operate at the cursor location in a Text View. The Font command opens a dialog allowing customization of the view.

The remaining five items allow you to modify attributes of GPSS World Objects. Expression Window and Plot Window open a dialog which allow you to change the contents of an existing dynamic Expression Window or Plot Window. Insert Block opens the Block Input Menu from which you can open a Block Creation Dialog. These Dialogs are available for guiding the creation of GPSS Blocks. When you complete a Block Creation Dialog and click OK, the new Block Statement is inserted after the Insertion Point in the Model. Block Statements created this way contain tabs. You can adjust tabstops in the Report page of the Model Object's Settings. Insert Experiment opens a dialog which allows you to automatically generate either an efficient screening experiment or a sophisticated optimizing experiment and insert it into a Model Object. See Chapter 13 of this manual for a discussion of the Automatic Experiment Generators.

Edit / Settings allows you to view and modify the Settings of a Model, Simulation, or Report Object. These attributes are discussed in detail below.

The Search Menu

The Search Menu helps you navigate inside the text view of an object.

The first item, Find / Replace, opens a dialog that lets you move to the next occurrence of specific text, and optionally replace it. A Replace All option is available, as well.

The Go To Line item will jump to a line number in the text. This is useful at times when an error message from a simulation mentions a line number.

The next set of items is for Bookmarks. They let you place invisible marks that get saved with the object. They form a circular list that you can traverse via the appropriate menu commands or keystrokes. The Next Bookmark menu command jumps to that position in the text corresponding to the next Bookmark in the list. Mark enters a Bookmark at the current cursor position. Unmark removes the current Bookmark. Unmark All removes all Bookmarks, Select to Bookmark selects text from the current cursor position to the current Bookmark position.

The last two items in the Search menu deal with Translation error messages. When you try to Create a Simulation Object from a Model which contains syntax errors, a circular list of error messages and locations is built into the Model Object, replacing any that was there before. This list becomes part of the Model Object and is saved with it. To traverse the list in either direction use the Next Error and Previous Error menu commands to display the error message in the Status Line at the bottom of the Main Window. At the same time the cursor is placed just before the error in the Text View so you can correct it. The keyboard accelerators b+a+N and b+a+P let you navigate the list easily from the keyboard.

The View Menu

The View menu includes menu commands for controlling what is shown in a few of the windows.

The first item, Notices, allows you to view the notices concerning GPSS World. You can update them from minutemansoftware.com if you need to.

With the second item, Toolbar, you can hide or show the Main Window's Toolbar by toggling the first item Toolbar.

The third item, Entity Details, lets you change the format of some of the dynamic simulation windows to show more or less detail onscreen.

The last menu item, Clock, toggles a switch in the current Simulation Object. If this switch is on in the current Simulation Object, changes in the System Clock of the simulation are displayed in the lower right of the Status Line of the Main Window when one of that Simulation Object's views is the active window. This is a handy way to assure yourself that a simulation is indeed running, but it slows down the simulation somewhat.

The Command Menu

The Command Menu is concerned with creating and manipulating Simulation Objects. The Create Simulation menu command invokes the high performance Translator to create a Simulation Object based on the Model Statements in an existing Model Object and its Include-files. Normally you will encounter errors that must be corrected (see Search / Next Error, above). The Retranslate menu command is available to perform the Translation again when errors have been corrected.

Next, Repeat Last Command is an easy way to do some action again on behalf of the same Object.

The remaining menu commands represent formal GPSS Commands. Most have accelerator keys for easy use and most can be loaded into a function key, as well. These menu commands are disabled unless the current Simulation Object is ready for them.

You can click on the last item in the Command submenu, Custom, in order to write your own Model Statement, not listed elsewhere.

The Window Menu

The top two items in the Window Menu can be used to tidy up when many windows are open in the Client Area of the Main Window. Tile will cover the client are of the Main Window with a small version of all open windows and Cascade will stack them in a handy stack where all title bars can be seen.

The next two items have submenus themselves. They are used to open Windows and Snapshots on existing Simulation Objects. These individual windows are discussed below. They are disabled until the current Simulation Object is ready to oblige.

The Help Menu

The Help menu can be used to start the Online Help system. In addition, the bottom item About GPSS World displays the software version and the license agreement.

2.2.3. Settings

Settings are collections of values that form a common thread throughout most of the GPSS World Objects. They are used to control the simulation, the appearance of reports, and the contents of windows and loadable function keys.

Settings are inherited. When you Create a Simulation Object, it inherits its initial Settings from its parent Model Object. So if you want to set values for all the simulations in your project, you should set them in the Model Object.

Similarly, Report Objects inherit their settings from the Simulation Object that created them. In this way, the Report contains a read-only record of the Settings in effect when the simulation was run.

Text Objects are different. They are mere representations of plain text files and do not contain a copy of Settings. This is the reason that they are the only GPSS World Objects that can be opened by external text editors. The other objects contain Settings, Bookmarks, and in the case of Model Objects, Result Lists, that are saved with the object and that confound external word processors. If you need to, you can always transfer just the text to and from the text view of these GPSS World Objects using the Windows clipboard.

To open a Settings Notebook you must first select an open GPSS World Object. Then, its Settings are viewed or modified by selecting

Edit / Settings

after clicking on the GPSS World Object to be changed. This presents the Settings Notebook for that Object, with 5 tabbed pages.

The Simulation Page

Figure 2—14. The Simulation Page of the Settings Notebook

The Simulation Page contains several values that you can change which affect the limits and behavior of running simulation.

The Poll Count Setting is the number of Block entries to be attempted before checking for any kind of interruption, such as a Command from the user.

If you use a lot of GPSS Transaction Parameters in your model, you can speed up simulations a little by putting them into a Parameter Block. To do this enter the number of Parameters to be blocked into the Parameter Block Size field, and the Parameter number of the first Parameter in the block in the Parameter Block First field. If you are using Names instead of numbers to refer to these Parameters, you should control the values given to Parameter Names by using EQU Statements.

The Max Evaluation Depthis used to protect against circular references in sets of PLUS Procedures. If your simulation is highly nested without circular references, you can increase this value to accommodate any level of nested Procedure calls.

The Stack Size is used to allocate stack space for nested PLUS Procedures and library procedures. You can save space by decreasing this value, but if you get a Stack Overflow Error Stop during a simulation, you may have to increase it.

The Integration Tolerance field is used by the continuous simulation phase. If you loosen this tolerance by making it larger, your integrations will be faster but may lose some accuracy.

The Max Memory Requestplaces a limit on the acquisition of RAM memory for structures such as tables and matrices. Such a limit is useful to catch errors, but you can increase it as necessary. If your RAM memory demands exceed that available in your computer, your operating system's virtual memory manager will have to increase its disk activity and perhaps its disk swap space usage significantly.

The four checkboxes at the bottom of the page control GPSS/PC Compatibility, which is available only in the Commercial Version, and how Data Stream errors are to be handled in the simulation.

CHECK the GPSS/PC Compatibility checkbox to operate the simulation in GPSS/PC Compatibility mode as described above in Section 1.5. This option automatically invokes the Single Calendar Day option, described next.

CHECK the Switch * and # checkbox to cause the * character to be used for multiplication and # for GPSS indirect addressing instead of the other way around.

CHECK the Single Calendar Day checkbox to cause simulations to use a single FEC time segment list instead of multiple ones. In certain simulations this may be a little faster, but will not alter the results of the simulation.

CHECK the I/O Stream Error Stopscheckbox if you want any errors other than "File Not Found" and "End of File" encountered by Data Streams in a simulation to HALT the simulation. If this box is unchecked you can handle such errors yourself within the simulation. See Section 4.16 for more information on Data Streams.

The Reports Page

Figure 2—15. The Reports Page of the Settings Notebook

The Reports Page is concerned primarily with the appearance of Reports and Plots.

The Standard Report Options groupbox contains the itemized GPSS Entity subreports to be included in each Standard Report. Check those to be included.

CHECK the Create Standard Reports checkbox to enable the creation of Standard Reports automatically when every simulation ends (i.e. when the Termination Count reaches zero). The REPORT Command is still available even if this is left unchecked.

CHECK the In Windows checkbox to open a Text View of each Report Object instead of just saving them in a file. This checkbox depends on the previous checkbox being checked,

Check the Six Places checkbox to set the printed precisionof fractional real values to 6 decimal places instead of 3 in Reports and Status Messages.

Check the Scientific checkbox to use the mantissa-exponent representation of extreme numbers in reports and in Data Streams.

Below the Standard Reports Options groupbox are four more Settings.

The Saved Plot Points value tells GPSS World how much space to allocate to a circular buffer for recent Plot points. If you scroll or print a Plot Window, these values are used to rebuild the plot. If you don't have enough, the leftmost segment of the scrolled or printed plot will be missing. A value too large can waste virtual memory.

Check the Suppress Page Numbers checkbox to prevent GPSS World from inserting page number headers when printing the object's Text View.

Check the PLUS Tracecheckbox to enable the Journalizing of a trace message for each PLUS Procedure invocation executed by your Simulation Object. Arguments are evaluated before writing them to the Journal Window. If you insert calls to some simple procedure and turn on the PLUS Trace you will get a trace of your variables (i.e. the ones used as arguments) in the Journal Window.

Check the Silence checkbox if you errors associated with this object to be reported silently, with no audible beep.