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Chapter 7 Slide Show


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Chapter 7 Slide Show

  1. 1. Chapter 7 What Can Computers Do For Me?
  2. 2. How important is the material in this chapter to understanding how a computer works? <ul><li>4 </li></ul>
  3. 3. How important is the material in this chapter to understanding how to use a computer? <ul><li>3 </li></ul>
  4. 4. What types of problems are Computers good at? <ul><li>Problems that involve </li></ul><ul><ul><li>Storage and </li></ul></ul><ul><ul><li>Retrieval of Data </li></ul></ul><ul><ul><li>Manipulation of Data </li></ul></ul><ul><ul><li>Mathematical Calculations </li></ul></ul>
  5. 5. When would a computer’s storage and retrieval skills help me? <ul><li>Word Processing </li></ul><ul><li>Database </li></ul><ul><li>Multimedia </li></ul><ul><li>Communications </li></ul>
  6. 6. How does a computer’s computational capabilities help me? <ul><li>Personal Finance </li></ul><ul><li>Forecasting (weather, economic) </li></ul><ul><li>Engineering and Science </li></ul><ul><li>Graphics and animation (games) </li></ul>
  7. 7. What Else can a Computer Help me with? <ul><li>Manipulation of Date </li></ul><ul><ul><li>Creation of data in spreadsheets and word processing. </li></ul></ul><ul><ul><li>Entering data into a database </li></ul></ul><ul><ul><li>Formatting data in a word processing program. </li></ul></ul><ul><ul><li>And many more … </li></ul></ul>
  8. 8. What do good applications have in Common? <ul><li>They are particularly amenable to computer solution. </li></ul><ul><ul><li>They depend on the retrieval, manipulation, and storage of data. </li></ul></ul><ul><li>They can be precisely described in a model which is well understood. </li></ul><ul><li>The process can be extensively monitored by the user (such as watching what you are typing in a word processor or listening to music that you’re playing). </li></ul>
  9. 9. Why can a computer guide astronauts into space but not predict the stock market? <ul><li>Space travel is governed by the laws of physics which are well known. </li></ul><ul><li>There are mathematical formulas that describe these laws and they can easily be programmed. </li></ul><ul><li>There are no known formulas for predicting the stock market. </li></ul><ul><li>So you just have to use general principles and expertise to determine what to do. </li></ul>
  10. 10. If programs that predict the stock market are unreliable, how can I tell when other computer programs might give unreliable results? <ul><li>This section emphasizes material that was discussed in chapter five and could better be phrased as, how can software developers be confident that the software that they designed works. </li></ul><ul><li>Specifications </li></ul><ul><li>Design </li></ul><ul><li>Implementation </li></ul><ul><li>Testing </li></ul><ul><li>Maintenance </li></ul><ul><li>MODELS AND SIMULATIONS. </li></ul>
  11. 11. For problems that a computer can solve, what process should I use to get an answer? <ul><li>This section of the book is generally talking about using commercial programs to solve problems. </li></ul><ul><li>One possible example is to use a spreadsheet to set up a monthly budget. </li></ul><ul><li>The general principles are similar to the way that programmers design software as we saw in chapter 5. </li></ul>
  12. 12. Solving Problems (continued) <ul><li>Stepwise refinement (top down methodology) </li></ul><ul><li>Setting up a budget </li></ul><ul><ul><li>List sources of income and total them up </li></ul></ul><ul><ul><li>List fixed expenses (rent, car payment, insurance etc) and deduct from income </li></ul></ul><ul><ul><li>List non-discretionary expenses and estimate such as utilities, food, gasoline. </li></ul></ul><ul><ul><li>How much is left? </li></ul></ul><ul><ul><li>Divvy it up based on experience. </li></ul></ul>
  13. 13. Can some computers solve problems that other computers can’t? <ul><li>No </li></ul><ul><li>But sort of </li></ul><ul><li>In principle the answer is no, but for practical purposes, some software is available only on certain platforms and therefore you can’t use those programs on all computers. </li></ul><ul><li>Also some computers lack certain “unimportant” features such as sound or color. </li></ul>
  14. 14. What are Turing Machines? <ul><li>A mathematical model of a computer consisting of </li></ul><ul><ul><li>A tape on which data is placed that is infinitely long in one direction. </li></ul></ul><ul><ul><li>A head that can read or write data to the tape and move from cell to cell </li></ul></ul><ul><ul><li>A control that can change states, and that based on the current state and content of the tape can perform actions with the tape head. </li></ul></ul>
  15. 15. Turing Machines (continued) <ul><li>Explain Example 1 on page 188-190 </li></ul><ul><li>You should make sure that you understand Example 2. </li></ul>
  16. 16. What do Turing Machines have to do with computers today? <ul><li>A Turing machine is a theoretical model of modern computer in terms of its capabilities </li></ul><ul><ul><li>The tape represents memory for data </li></ul></ul><ul><ul><li>The control represents the program being run </li></ul></ul><ul><li>Different types of Turing machines are equivalent to each other is capabilities but not in speed or convenience. </li></ul>
  17. 17. Universality of Computers <ul><li>All computational tasks can be decomposed into simple instructions that any computer can execute. </li></ul><ul><li>Even though different computers use different instruction sets, the instructions that one computer lacks can be programmed using instructions that it does have. </li></ul><ul><li>Computers differ in how fast they can solve a problem, not whether they can solve a problem. </li></ul>
  18. 18. If all computers are universal, how do they differ? <ul><li>Speed </li></ul><ul><li>Storage capacity </li></ul><ul><li>“ Special” features such as sound, color, graphics, animation, … </li></ul><ul><li>Some software may not actually be available on various platforms </li></ul><ul><li>User interfaces differ. </li></ul>
  19. 19. How can I decide what machine I should buy? <ul><li>What do you want to do with your computer, especially specialized tasks? Pick out software packages. </li></ul><ul><li>Compatibility with other users. </li></ul><ul><li>How important is portability? </li></ul><ul><li>Price – how much can you afford? </li></ul><ul><li>What hardware requirements are there for the software that you need? </li></ul>
  20. 20. Summary <ul><li>Computers excel at storing, retrieving and manipulating data at great speed. </li></ul><ul><li>Computers excel at presenting results in both textual and graphical form </li></ul><ul><li>For a computer to solve a problem, it must be precisely specified, and a detailed algorithm must be developed to meet this specification. </li></ul><ul><li>The implementation of the algorithm (software) must be tested thoroughly to be sure that it does work. </li></ul><ul><li>Relevant data must be obtained and used. </li></ul>
  21. 21. Summary (continued) <ul><li>If problems do not satisfy these characteristics, computers may not be useful in solving them. </li></ul><ul><li>Complex software likely has errors, so users should be mindful of this fact. </li></ul><ul><li>Top-down refinement of a problem is a good technique for creating a solution. </li></ul><ul><li>All computers are alike (more or less). </li></ul><ul><li>In selecting a computer to purchase, you should proceed with a logical and methodological approach. </li></ul>
  22. 22. Terminology <ul><li>Algorithm </li></ul><ul><li>Algorithmic thinking </li></ul><ul><li>Data structure </li></ul><ul><li>Database </li></ul><ul><li>Decomposition </li></ul><ul><li>Modeling </li></ul><ul><li>Parity bit </li></ul><ul><li>refinement </li></ul><ul><li>Repetition </li></ul><ul><li>Simulation </li></ul><ul><li>Spreadsheet </li></ul><ul><li>Top-down methodology </li></ul><ul><li>Turing Machine </li></ul><ul><li>Universality of Computers </li></ul>