1. Invitation to Computer Science 5th Edition
Chapter 13
Simulation and Modeling

2. Objectives In this chapter, you will learn about:
Computational modeling
Running the model
Visualizing results
Invitation to Computer Science, 5th Edition

3. Introduction Computational modeling
Having a major impact on a number of quantitative fields, including:
Chemistry, biology, medicine, meteorology, ecology, geography, and economics
Invitation to Computer Science, 5th Edition 3

4. Computational Modeling
Scientific method
Entails observing the behavior of a system and formulating a hypothesis that tries to explain its behavior
Model
Abstraction of the system being studied
Computer simulation
Physical system is modeled as a set of mathematical equations and/or algorithmic procedures that capture the fundamental characteristics and behavior of a system
Invitation to Computer Science, 5th Edition 4

5. Computational Modeling (continued)
Why construct a simulation model?
Existence
Physical realization
Safety
Speed of construction
Time scale
Ethical behavior
Ease of modification
Invitation to Computer Science, 5th Edition

6. Figure 13.1 Using a Simulation in an Interactive Design Environment
Invitation to Computer Science, 5th Edition

7. Computational Models, Accuracy, and Errors
Issues in modeling
Achieving proper balance between accuracy and complexity
We may not know, in a mathematical sense, exactly how to describe certain types of systems and behaviors
Stochastic components
Parts of the system that display random behavior
Invitation to Computer Science, 5th Edition

8. An Example of Model Building
Discrete event simulation
One of the most popular and widely used techniques for building computer models
When we process an event:
We change the state of the simulated system
Invitation to Computer Science, 5th Edition

9. Figure 13.2 Example of Simulated Events
Invitation to Computer Science, 5th Edition

10. Figure 13.3 System to Be Modeled
Invitation to Computer Science, 5th Edition

11. Figure 13.4 Algorithm for New Customer Arrival
Invitation to Computer Science, 5th Edition

12. Figure 13.5 Statistical Distribution of Customer Service Time
Invitation to Computer Science, 5th Edition

13. Figure 13.6 Algorithm for Generating Random Numbers That Follow the Distribution Given in Figure 13.5
Invitation to Computer Science, 5th Edition

14. An Example of Model Building (continued)
Uniform random number
Random integer that takes on one of the values 1, 2, 3, , 100 with equal likelihood
Garbage in-garbage out
Results you get out of a simulation model are only as good as the data and the assumptions put into the model
Invitation to Computer Science, 5th Edition

15. Figure 13.7 Algorithm for Customer Departure Event
Invitation to Computer Science, 5th Edition

16. Figure 13.8 The Main Algorithm of our Simulation Model
Invitation to Computer Science, 5th Edition

17. Running the Model and Visualizing Results
Scientific visualization
How do you visualize data in a way that highlights its important characteristics and simplifies its interpretation?
Concerned with issues such as data extraction and data manipulation
Computer graphics
Concerned with the technical issues involved in information display
Invitation to Computer Science, 5th Edition

18. Figure 13.9 Using a Two-Dimensional Graph to Display Output
Invitation to Computer Science, 5th Edition

19. Figure 13.10 Using a Two-Dimensional Graph to Display and Compare Two Data Values
Invitation to Computer Science, 5th Edition

20. Figure 13.11 Three-Dimensional Image of a Region of the Earth’s Surface
Invitation to Computer Science, 5th Edition

21. Figure 13.12 Three-Dimensional Model of a Methyl Nitrite Molecule
Invitation to Computer Science, 5th Edition

22. Running the Model and Visualizing Results (continued)
Image animation
One of the most powerful and useful forms of visualization
Goal of scientific visualization techniques
To take a massive data set and present it in a way that is more informative and more understandable for the user of that data
Invitation to Computer Science, 5th Edition

23. Figure 13.13 Visualization of Gas Dispersion
Invitation to Computer Science, 5th Edition

24. Figure 13.14 Use of Animation to Model Ozone Layers in the Atmosphere
Invitation to Computer Science, 5th Edition

25. Summary
A model is an abstraction of a system that behaves much like the original
Computer simulation
Physical system is modeled using mathematical equations and/or algorithmic procedures
Model is translated into a high-level language program and executed
Invitation to Computer Science, 5th Edition

26. Summary (continued) Computational models Scientific visualization
Allow the use of an interactive design methodology
Scientific visualization
Visualizing data to highlight its important characteristics and simplify its interpretation
Invitation to Computer Science, 5th Edition