The sim C++ library -- version 2.0

A simulation is the execution in time of a model, represented by a computer program, that gives information about the system being investigated. The library sim adopts the method of the Discrete Event Simulation. With this approach, the components of the model consist of events, which are activated at certain points in time and in this way affect the overall state of the system. The points in time that an event is activated are randomized, so no input from outside the system is required. Events exist autonomously and they are discrete so between the execution of two events nothing happens. The library sim provides an event-based, as well as a process-oriented approach of writing a simulation program. With the process-oriented approach, the components of the program consist of entities, which combine several related events into one entity. Sim is written in the C++ programming language. The library provides classes, that can be used by writing a C++ simulation program. We provided the library with such a functionality, that the resulting language is similar to SIMULA. The library can be compiled to both a pure ASCII version as well as a HUSH version. If you run the library in HUSH mode, you can use the graphical features.

Differences between 2.0 and 1.0 versions

You should always create and run a session.
If you link your programs to the Hush version you always get graphical output. As a consequence the simulation constuctor doesn't get tk as an argument anymore.
The histogram constructor gets a widget-path and the arguments as a string of options. The additional options are for the formatting of the output. The output for the (cumulative) frequency graph and table contains no statistis anymore. The statistics can be generated by adding an extra histogram.
The methods suppress and scan of the simulation class don't exist anymore. You can use the init method. Grafical output can be formatted.
The confidence method of the analysis class takes an options parameter now and the operator<< method has been removed. Invoking a method of this class will immediately result in output, which can be formatted.
The screen class behaves different. It is like the hush-canvas class except for the world-coordinates it uses. The widgets as the clock etc.. have been made independent.
The generator gets three seeds instead of one.

Advantages

One program structure (sources and interface are clearer now).
The period for the generator is a factor of 7000 higher.
The graphical features are much more powerful. You can format almost anything you want (sizes, colors etc..). Furthermore the widgets (histogram,results from analysis and simulation,screen, simulationclock,control,query) can be packed, be embedded in a screen or made toplevel (instead of only be made toplevel).

Disadvantages

Keep us informed. Mail any comments to eliens@cs.vu.nl.