1. Computer Programming w/Eng. Applications
CS 2073
Computer Programming w/Eng. Applications
Ch 1
Turgay Korkmaz
Office: SB
Phone: (210)
Fax: (210)
web:

2. Name
Addr
Content
Lecture 2
Lecture++;

3. Ch1: Engineering Problem Solving
Read Section 1.1 from the textbook
Recent Engineering Achievements
Microprocessor
Moon landing
Satellites
Computer-aided design (CAD) and manufacturing
Jumbo jet
Advance computer materials
Computerized axial tomography
Genetic engineering
Lasers
Optical fiber
Changing Engineering Environment
Communication skills (oral, written)
Concept-Design-process-manufacture
Interdisciplinary teams
Word marketplace
Analyzing-Synthesizing
Societal Context

4. Ch1: Engineering Problem Solving (cont’d)
Section 1.2: Computing Systems
Computer: a machine that is designed to perform operations (set of instructions called program) to achieve a specific task (e.g., 3+4)
Hardware: computer equipment (e.g., keyboard, mouse, terminal, hard disk, printer)
Software: programs that describe the steps we want the computer to perform.

5. Computer Hardware CPU - Central processing unit
Internal
Memory
External
Memory
CPU
Processor
Input
Output
ALU
In this sense, do you think we are like a computer?
Yes + we have intelligence
CPU - Central processing unit
ALU - Arithmetic and logic unit
ROM - Read only memory
RAM - Random access memory

6. Computer Software
Operating System - Provides an interface with the user
unix, windows, linux, ...
Software Tools
word processors (MicrosoftWord, WordPerfect, ...)
spreadsheet programs (Excel, Lotus1-2-3, ...)
mathematical computation tools (MATLAB, Mathematica, ...)
Computer Languages
machine language
assembly language
binary language
high level languages (C, C++, Ada, Fortran, Basic, java)
WE WILL STUDY C PROGRAMMING LANGUAGE
General purpose, machine-independent language
Developed at Bell Labs in 1972 by Dennis Ritchie
American National Standards Institute(ANSI) approved ANSI C standard in 1989

7. Executing a Computer Program
Compiler
Converts source program to object program
Linker
Converts object program to executable program

8. Some Key Terms and Software Life-Cycle Phases
Source Program
printable/Readable Program file
Object Program
nonprintable machine readable file
Executable Program
nonprintable executable code
Syntax errors
reported by the compiler
Linker errors
reported by the linker
Execution/Run-time errors
reported by the operating system

9. PROBLEM SOLVING
Very Important

10. Ch 1.3 Problem Solving Methodology (must read)
1. State the problem clearly
2. Describe the input/output information
3. Work the problem by hand, give example
4. Develop a solution (Algorithm Development)
and Convert it to a program (C program)
5. Test the solution with a variety of data

11. Example 1 1. Problem statement Compute the straight line
(x1,y1)
(x2, y2)
1. Problem statement
Compute the straight line
distance between two points in a plane
2. Input/output description
Point 1 (x1, y1)
Distance between two points (distance)
Point 2 (x2, y2)

12. Example 1 (cont’d)
3. Hand example
side1 = = 3
side2 = = 2

13. Example 1 (cont’d) 4. Algorithm development and coding
a. Generalize the hand solution and list/outline the necessary operations step-by-step
Give specific values for point1 (x1, y1) and point2 (x2, y2)
Compute side1=x2-x1 and side2=y2-y1
Compute
Print distance
b. Convert the above outlined solution to a program using any language you want (see next slide for C imp.)

14. Example 1 (cont’d)

15. Example 1 (cont’d) 5. Testing
After compiling your program, run it and see if it gives the correct result.
Your program should print out
The distance between two points is 3.61
If not, what will you do?

16. Modification to Example 1
How will you find the distance between two other points (2,5) and (10,8)?
x1=2, y1=5, x2=10, y2=8,

17. Few Issues
We will study the details of this program and C language later…
The programming language is not the main part of problem solving!
Main part is to figure out the necessary steps and their orders (if you can develop solution then coding is easy)
For the same problem, we may come up with different and yet correct solutions.
Computers cannot think or develop a solution, they just follow your instructions and do the operations faster
Then how do computers do many things? Even play a game, for example chess?

18. Simple examples to develop solutions

19. Compute the area of a triangle
State problem
I/O
Hand example
Develop solution
and Coding
Testing
x=3 cm
y=4 cm
area x y
area = ½ * 3 *4 = 6 cm2
Get values of x and y
Compute area = ½*x*y
Print area

20. Given two complex numbers z1=a1+b1*i and z2=a2+b2*i, find z3= z1+z2
State problem
I/O
Hand example
Develop solution
and Coding
Testing
Get a1 b1 a2 b2
Compute a3 = a1 + a2
Compute b3 = b1 + b2
Print z3 = a3 + b3 * i

21. Given the number of seconds, find number of hours, minutes and seconds
total_sec M S
State problem
I/O
Hand example
Develop solution
and Coding
Testing
3675 seconds can be written as
1 hour 1 min 15 sec
Get total_sec
H = total_sec / 3600 (integer division)
M = (total_sec – (H*3600)) / 60
M = (total_sec mod 3600) / 60
S = total_sec – (H*3600) – (M*60)
Print H hour, M min, S sec

22. A little bit difficult examples to develop solutions
Some problems are from How to Solve it: Modern Heuristics by Michalewicz and Fogel. Springer 2004.

23. Example: Average speed
Suppose a car goes from city A to city B with speed of 40 mph and immediately comes back with the speed of 60 mph.
What is the average speed?
Can you generalize this solution and outline step by step to find average speed when the speed from A to B is X and the speed from B to A is Y?

24. Quiz: Dimensions of a rectangle ranch?
A farmer has a rectangular ranch with a perimeter of P=110 meters and an area of A=200 square meters.
What are the
dimensions of
his ranch?
What are the dimensions for any P and A? y x

25. Example: Make a triangle with maximum area
Suppose you have a stick with the length of L meters. You want to divide it into three pieces with the length of x, y, and z meters, and make a triangle
Find x, y, z such that
the area of that triangle
is maximum. L x y z

26. Example: Climbing a wooden post
A snail is climbing a wooden post that is H=10 meters high.
During the day, it climbs U=5 meters up.
During the night, it falls asleep and slides down D=4 meters.
How many days will it take the snail to climb the top of the post?
Given that H > U > D. Can you generalize your solution for any H, U, and D?

27. Minimum number of coins
Suppose you want to give x=67 cents to a person, what is the minimum number of coins
You have many 25, 10, 5, 1 cents

28. Example: Assign letter grades
Suppose I have your grades as follows
name final midterm avg_hw quizze letter
aaaa ?
bbbb ? …
How can I assign letter grades?

29. Example: Sum of numbers
Given n (for example n=1000), compute
sum = …+n
sum_odd = …+(2n+1)
ln2=1- 1/2 + 1/3 - 1/4 +…  1/n

30. If you want this course to be easy, you must learn how to act like a computer 
Develop necessary step-by-step instructions to perform the following real-life tasks like a computer
Driving a car
Following a direction to find an address
Cook something
Search a word in a dictionary
Make a phone call
Now, its your turn to think of a problem and give STEP-BY-STEP instructions…
For the same problem, we may have different and yet correct solutions. So, …

31. Ten heuristics for problem solving How to Solve it: Modern Heuristics by Michalewicz and Fogel. Springer 2004.
Don’t rush to give an answer, think about it
Concentrate on the essentials and don’t worry about the noise (tiny details)
Sometimes finding a solution can be really easy (common sense), don’t make it harder on yourself
Beware of obvious solutions. They might be wrong
Don’t be misled by previous experience

32. Ten heuristics for problem solving How to Solve it: Modern Heuristics by Michalewicz and Fogel. Springer 2004.
Start solving. Don’t say “I don’t know how”
Most people don’t plan to fail, they just fail to plan!
Don’t limit yourself to the search space that is defined by the problem. Expand your horizon
Constraints can be helpful to focus on the problem at the hand
Don’t be satisfied with finding a solution, look for better ones
Be patient. Be persistent!

33. A Checklist for Engineering Reasoning http://www. criticalthinking
1. All engineering reasoning expresses a purpose. Take time to state your purpose clearly.
Distinguish your purpose from related purposes.
Check periodically to be sure you are still on target.
Choose realistic and achievable purposes.

34. 2. All engineering reasoning seeks to figure something out, to settle some question, solve some engineering problem.
Take time to state the question at issue clearly and precisely.
Express the question in several ways to clarify its meaning and scope.
Break the question into sub-questions.
Determine if the question has one right answer, or requires reasoning from more than one hypothesis or point of view.

35. 3. All engineering reasoning requires assumptions.
Clearly identify your assumptions and determine whether they are justifiable.
Consider how your assumptions are shaping your point of view.
Consider the impact of alternative or unexpressed assumptions.
Consider the impact of removing assumptions.

36. 4. All engineering reasoning is done from some perspective or point of view.
Identify your specific point of view.
Consider the point of view of other stakeholders.
Strive to be fair-minded in evaluating all relevant points of view.

37. 5. All engineering reasoning is based on data, information, and evidence.
Validate your data sources.
Restrict your claims to those supported by the data.
Search for data that opposes your position as well as alternative theories.
Make sure that all data used is clear, accurate, and relevant to the question at issue.
Make sure you have gathered sufficient data.

38. 6. All engineering reasoning is expressed through, and shaped by, concepts and theories.
Identify key concepts and explain them clearly.
Consider alternative concepts or alternative definitions of concepts.
Make sure you are using concepts and theories with care and precision.

39. 7. All engineering reasoning entails inferences or interpretations by which we draw conclusions and give meaning to engineering work.
Infer only what the data supports.
Check inferences for their internal and external consistency.
Identify assumptions that led you to your conclusions.

40. 8. All engineering reasoning leads somewhere or has implications and consequences.
Trace the implications and consequences that follow from your data and reasoning.
Search for negative as well as positive implications (technical, social, environmental, financial, ethical).
Consider all possible implications.