cs10051 section 600 introduction to computer science
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CS10051 Section 600 Introduction to Computer Science. Fall 2010 Dr. Angela Guercio Prof. Kathleen Stirbens. Objectives. In this chapter, you will learn about: The definition of algorithm The definition of computer science Overview of the course. What is an Algorithm?. - PowerPoint PPT PresentationTRANSCRIPT
CS10051 Section 600Introduction
to Computer Science
Fall 2010
Dr. Angela Guercio
Prof. Kathleen Stirbens
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Objectives
In this chapter, you will learn about:
The definition of algorithm
The definition of computer science
Overview of the course
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What is an Algorithm?
An algorithm is a well-ordered collection of unambiguous and effectively computable operations that, when
executed, produces a result and halts in a finite amount of time.
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Example of Algorithm
An algorithm is a list that looks like STEP 1: Do something STEP 2: Do something STEP 3: Do something . . . . . . STEP N: Stop, you are finished
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The Formal Definition of an Algorithm
Algorithm A well-ordered collection of unambiguous and
effectively computable operations that, when executed, produces a result and halts in a finite amount of time
Example: Make Pasta1. Boil two quarts of water
2. Add ½ lb of pasta in the water
3. Strain the water
4. Add the sauce
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The Formal Definition of an Algorithm (continued) Unambiguous operation
An operation that can be understood and carried out directly by the computing agent without needing to be further simplified or explained
Ex. Boil some water (ambiguous) Boil 2 quarts of water (unambiguous)
An operation that is unambiguous is called a primitive operation (or just a primitive) Q. - What are the primitives of a computer? A. -
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The Formal Definition of an Algorithm (continued)
Effectively computable Computational process exists that allows computing
agent to complete that operation successfully Note that a given collection of operations may be an
algorithm with respect to one computing agent, but not with respect to another computing agent!!
Example of not effectively computable operations: Write all the real numbers between 0 and 1.
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The Formal Definition of an Algorithm (continued)
The result of the algorithm must be produced after the execution of a finite number of operations
i.e. Can the user of the algorithm observe a result produced by the algorithm?
A result can be a sign, a sound, an alarm, a number, a message of error, ect…
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The Formal Definition of an Algorithm (continued) It halts in a finite amount of time.
Infinite loop The algorithm has no provisions to terminate A common error in the designing of algorithms
Do not confuse, "not finite" with "very, very large".
Q. - Is this loop “finite”, “infinite”, or “very, very large”?Step 1. Write the number 1 on the board.Step 2. Add 1 to the number you just wrote and write the result
on the boardStep 3. Repeat Step 2.Step 4. Stop.
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The Importance of Algorithmic Problem Solving Algorithmic solutions can be:
Encoded into some appropriate language Given to a computing agent to execute
The computing agent Would mechanically follow these instructions and
successfully complete the task specified Would not have to understand
Creative processes that went into discovery of solution Principles and concepts that underlie the problem
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Which of those is an algorithm? Write all the possible numbers on a paper. Fill 1 cup of sugar. Mix it to 3 cups of milk. Think of a number. Add 20 to it. Either wet your hair or lather your hair.
Then rinse your hair. If your hair are dirty, wet your hair; lather
your hair; rinse your hair; else go back to study.
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Common misconceptions about Computer Science
Misconception 1
Computer science is the study of computers
Misconception 2
Computer science is the study of how to write computer programs
Misconception 3
Computer science is the study of the uses and applications of computers and software
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The Definition of Computer Science Computer science is the study of algorithms
including
1. Their formal and mathematical properties 2. Their hardware realizations 3. Their linguistic realizations 4. Their applications
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1. Their formal and mathematical properties
It is not enough to design an algorithm to solve a problem.
We must worry about some additional properties of an algorithm: How efficient is it? What kinds of resources must be used to execute
it? How does it compare to other algorithms that solve
the same problem?
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2. Their hardware realizations Computing entities are required to execute
algorithms Computing entities are not necessarily machines! However our interest will lie with algorithms that execute
on computing entities called "computers". How are computer constructed?
The emphasis of the course will be on the logical construction of a computer, not the physical construction.
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3. Their linguistic realizations Which language do we use to code the
algorithms? We will start with one linguistic realization,
called pseudocode and later will look at possible different realizations in various programming languages.
In particular we will do some introductory programming in C++.
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4. Their applications
What are some of the many important and popular applications of computers in current use including: numerical problem solving information retrieval graphics networking artificial intelligence telecommunications modeling and simulation
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Overview of the course 1. The algorithmic foundations of computer science. (Ch 1-3) 2. The hardware world. (Ch 4-5) 3. The virtual machine. (Ch 6-7) 4. The software world. (Ch 8-11) 5. Applications. (Ch 12-14) 6. Social issues. (Ch 15)
Note these correspond to the levels of the pyramid on the cover of your text.
Each level addresses one aspect of the definition of computer science
Computer science/Algorithms
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Figure 1.9Organization of the Text into a Six-Layer Hierarchy
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Summary Computer science is the study of algorithms
An algorithm is a well-ordered collection of unambiguous and effectively computable operations that, when executed, produces a result and halts in a finite amount of time
If we can specify an algorithm to solve a problem, then we can automate its solution
Computers developed from mechanical calculating devices to modern electronic marvels of miniaturization
BE SURE TO CHECK THE CLASS WEBSITE DAILY FOR YOUR:
Reading assignmentsHomework assignmentsOther materials related to this course
http://www.personal.kent.edu/~aguercio/Fall10/CS10051-600Fa10.html