CS2 Winter 2005

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CS2Winter 2005

• Instructor Al Barr
• E-mail barradmin_at_cs.caltech.edu
• TA e-mail cs2staff_at_ugcs.caltech.edu

2
CS2 Course Objectives

• Introduction to Programming Methods
• Overview of CS concepts
• Limits of computation, scaling arguments,
  reusability,
• Design strategies
• Issues of Representation
• The "decomposition" process, divide and conquer,
  
• Data structures
• Stacks, heaps, lists, directed graphs, hash
  tables
• Algorithms
• 7 key algorithm structures whats the
  invariant, n log n complexity,
• Numerics
• Elements of CS history
• CS Pioneers

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Class Structure

• Ten Weeks
• Lectures and recitations
• 1 assignment per week
• Usually split into a design component and an
  implementation component. Sometimes will have
  written components.
• Design portion due separately, so can have two
  due-dates per week
• Implementation is programming in Java
• Using Sun NetBeans IDE (Integrated Development
  Environment)
• Java is an object oriented imperative language

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Administrative Issues

• Write name, e-mail, and intended major(s) on
  class list
• TAs still in process of being selected.
• Web site for this year is still being set up
• www.cs.caltech.edu/courses/cs2
• E-mail mailing list will be created

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Ends and Means

• You might think the class is about programming in
  Java
• But thats only a means to the end.
• The purpose of the class is to cover the
  fundamentals,
• the basic concepts that will have longevity even
  after Java is long gone.
• Each modern technology is usually quite short
  lived,
• But the principles behind the technology usually
  have longevity

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A Digression The Story of the Teleharmonium

• Patented 1897, Thaddeus Cahill
• first significant electronic musical instrument
• first fully completed model presented in 1906
• Based on mathematics of Fourier series
• (any periodic waveform can be represented
  arbitrarily closely as a sum of sines and cosines
  of different frequencies)
• F(x) S aN Cos(N p x/L) bN Sin(N p x/L)

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How would you design it?

• Took place before amplifiers (by 20 years)
• before invention of the vacuum tube
• Took place after the invention of the telephone
• And after the invention of the AC current
  generator
• 145 modified dynamos w/ specially geared shafts
  to produce alternating currents of different
  audio frequencies.
• Weighed 200 tons! Filled a factory.
• Linked directly to telephone network and to a
  series of telephone receivers fitted with special
  acoustic horns.
• Needed enough current (1 amp) for all combined
  listeners.
• Masked and disrupted all other signals on the
  phone line in NYC during performances

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Teleharmonium, conclusion
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Teleharmonium, conclusion

• Performances continued until 1916
• Made obsolete by radio
• See http//www.obsolete.com/120_years/machines/tel
  harmonium/
• Synthesis principles later adapted to Hammond
  Organ and many other electronic instruments.
• The moral of the story is that the mathematical
  and theoretical foundations long outlasted the
  implementation using the most modern technology
  of the time (generators, gears, and motors).
• As technologists and scientists, we need to focus
  on the mathematical and theoretical fundamentals
  to keep current.

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Is CS Fundamental?

• Is Computer Science a Science?
• (Or is it merely the study of boxes and arrows)?
• Unlike physics, CS not invented by Aristotle. (He
  was close see below
• . . . That physics, then, is a theoretical
  science, is plain from these considerations.
  Mathematics also, is theoretical, but whether its
  objects are immovable and separable from matter,
  is not at present clear. Aristotle, Metaphysics,
  Book VI, 350BC
• Can think of fundamental CS as study of how
  information might be stored and processed in
  material structures
• Includes digital and analog computation, like the
  Teleharmonium
• Is Information real?
• yes, related to entropy (Shannon)

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Ok, back to Design

• Internal design of text editor?
• ? Sequential, monolithic program? Why not?
• A good design would have three separate threads
  or processes
• one independent thread to manage the data in the
  text buffer
• one independent thread to handle the display of
  the text, updating continuously from the data
  buffer
• One thread to handle the interaction from the
  user (keyboard clicks, mouse commands, etc.)

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Programming Objects

• state descriptions compare to physical
  objects
• History of objects no silver bullet by Fred
  Brooks
• Work with TAs to help set up NetBeans, your
  Java environment
• See http//java.sun.com/docs/books/tutorial/java/c
  oncepts/index.html