Class 1: Class 1: What is Introduction Introduction Computer - PDF document

Class 1: Class 1: What is Introduction Introduction Computer Science ? CS150 Spring 2009 University of Virginia Computer Science Westley Weimer http://www.cs.virginia.edu/cs150 #2 The note on the inflected line is Let AB and CD be the two given numbers only difficult to you, because it is so not relatively prime. It is required to find easy. There is in fact nothing in it, the greatest common measure of AB and but you think there must be some CD . grand mystery hidden under that word inflected ! If now CD measures AB , since it also Whenever from any point measures itself, then CD is a common without a given line, you draw along measure of CD and AB . And it is manifest to any point in the given line, you that it is also the greatest, for no greater have inflected a line upon a given number than CD measures CD . line. Ada Byron (age 19), letter to Annabella Euclid’s Elements, Book VII, Proposition 2 (300BC) Acheson (explaining Euclid), 1834 #3 #4 I ask you: By the word operation, we mean any process which alters the mutual relation of two or What's the more things, be this relation of what kind it difference may. This is the most general definition, and would include all subjects in the universe... between Euclid Supposing, for instance, that the fundamental and Ada? relations of pitched sounds in the science of harmony and of musical composition were I have no idea what susceptible of such expression and you're talking about adaptations, the engine might compose when you say the word elaborate and scientific pieces of music of any degree of complexity or extent. “ask”. Bill Gates (deposition at Ada Byron, 1843 Microsoft’s anti-trust trial) #5 #6

Today's Class Geometry vs. Computer Science • Ada and Euclid • Geometry (mathematics) is about declarative knowledge: “what is” • Engineering and Science If now CD measures AB , since it also measures itself, • Moore's Law and Computing Power then CD is a common measure of CD and AB • The Liberal Arts • Computer Science is about imperative • Course Expectations knowledge: “how to” • Recursive Definitions and Languages Computer Science has little to do with • Nuclear Weapons beige (or spiffy black) boxes called “computers” and is not a real science. • Formal Languages and Systems #7 #8 Computer Science Science, Engineering or Other? “How to” knowledge: • Ways of describing information processes (computations) Language • Ways of predicting properties of information processes Logic #9 #10 Science? Engineering? “ Engineering is design under • Science involves understanding nature constraint … Engineering is synthetic through observation - it strives to create what can be, – About real things like bowling balls, black but it is constrained by nature, by holes, antimatter, electrons, comets, etc. cost, by concerns of safety, • Math and Computer Science are about reliability, environmental impact, fake things like numbers, graphs, manufacturability, maintainability functions, lists, etc. and many other such 'ilities.' ...” – Computer Science is a useful tool for doing real science, but is not a real science William Wulf and George Fisher, 2002 #11 #12

Liberal Arts Trivia: Music Liberal Arts Trivia: Psychology • Say the color each word is printed in: • Q. What is the name of a musical scale with • Green Red Blue twelve pitches, each a semitone or half step • Purple Blue Purple apart? Such a scale is nondiatonic, consisting entirely of half-step intervals and having no tonic due to the symmetry or equal spacing of • Blue Purple Red its tone. • Green Purple Green • Q. Name the effect that refers to the fact that naming the color of the first group of words is easier and quicker than the second. #13 #14 Apollo Guidance Computer, 1969 Let's Start With Classic Computers Why did they need to fit the 1 Cubic Foot guidance computer in the rocket? #15 #16 Measuring Computers How much power? • Apollo Computer: 61440 bits of changeable memory • 1 bit = smallest unit of information • Lab machines have 1 GB (RAM) – True or False – 1 Gigabyte = 1024 Megabytes, – 0 or 1 1 Megabyte = 1024 Kilobytes, You will understand this – If we start with 2 possible choices, and get 1 1 Kilobyte = 1024 Bytes, notation soon…but don’t worry bit, we can eliminate one of the choices if you don’t now 1 Byte = 8 bits > (* 1024 1024 1024 8) ~ 8.6 Billion bits 8589934592 > (round (/ (* 1024 1024 1024 8) 61440)) 139810 You have 139 810 times more power than AGC If Apollo Guidance Computer power is 1 inch, you have 2.2 miles! #17 #18

Computing Power 1969-present (in Apollo Control Computer Units) Constraints Computer Scientists Face 80,000,000 • Not like those for engineers: Moore’s “Law”: computing power 70,000,000 – Cost, weight, physics, etc. roughly doubles every 18 months! 60,000,000 – If today's ~20 Million times what people had 50,000,000 in 1969 isn’t enough for you, wait until 2011 40,000,000 and you will have ~80 Million times… 30,000,000 • More like those for Musicians and Poets: 20,000,000 – Imagination and Creativity 10,000,000 – Complexity of what we can understand 0 1969 1972 1975 1978 1981 1984 1987 1990 1993 1996 1999 2002 2005 2008 #20 So, what is computer science? Liberal Arts: ~1100 AD • Illiberal Arts • Science – arts for the non-free: pursued for economic – No: it's about fake things like numbers, not reasons about observing and understanding nature • Liberal Arts • Engineering – arts for the free : pursued for intrinsic – No: we don’t have to deal with engineering- reasons type constraints • Liberal Art #21 #22 The Liberal Arts Course language numbers Expectations Quadrivium (4 roads) Trivium (3 roads) Arithmetic Grammar Logic Music Rhetoric study of meaning in argument numbers written expression Comprehension Geometry for in time of discourse discovering quantification Astronomy truth of space We will see all of these in this class! #23 #24

Course Roadmap Like Drinking from a Firehose Like Drinking from a Firehose (Intellectual) Computer Science Liberal Arts Don’t be overwhelmed! 1st Class You will do fine. from Euclid and Ada to PS 1-6 Quantum Computing Lecture and Illiberal Arts the World Wide Web PS 7-9 ($$$$) It may hurt a little bit, and a lot of water will go It may hurt a little bit, and a lot of water will go by you, but you won’t go away thirsty! by you, but you won’t go away thirsty! #25 #26 Help Available Books • Me: Westley Weimer (call me “Wes”) Computational Thinking – Office Hours will be posted (after your surveys) A Whirlwind Introduction to the Third Millennial Liberal Art – Always available via email and forum , if I don’t from Ada and Euclid reply in 24 hours, send again and complain to Quantum Computing and the World Wide Web • Teaching Assistants: Zak Fry, Paul DiOrio, ??? A new book written for this course by – Structured lab hours in OLS 001. W 7-8, W 8-9 Professor David Evans (UVA) – Staffed lab hours in Small Hall Bonuses for helping us improve it: – Officse hours TBA (after your surveys) - Less pretentious title (?) • Web site: http://www.cs.virginia.edu/cs150 - More exciting cover - Notice any mistakes – Everything goes on the web, you should visit it often - Improve the writing or presentation “GEB” • Your classmates (read the course pledge “Course Book” carefully!) #27 #28 Background Expected What I Expect of You • Language: 1. Everything on the Course Pledge – Reasonable reading and writing in English – You should actually read it not just sign it (you will lose points on the problem sets if – Understanding of subject, verb and object your submission reveals that you didn’t read • Math: it!) – Numbers, add, subtract, multiply, divide 2. You are a “Jeffersonian Student” – Exponentiation, logarithms (we will review) 1.Believe knowledge is powerful • Logic: and , or , not 2.Interested in lots of things, ahead of your time • Computer Literacy: read email, browse 3.Want to use what you learn to do good things web 4.Care more about what you learn than grades and degree requirements If I ever appear to expect anything else, stop me! #29 #30

Many of you have fancy phones No ringing: you will look foolish #31 #32 A Course for Everyone! First Assignment • CLAS, SEAS, Commerce, Arch, etc. • Read Course Book Chapters 1-3 by tomorrow • 1 st , 2 nd , 3 rd , 4 th , 5 th Years, Community • Problem Set 0 (“Managing Mars with Scholars, Faculty Automatic Adjudication”) is due Midnight this • No background expected … but challenging Thursday even for students with lots of previous CS – It is very short courses • Due before CLAS drop deadline • Computer Science (future-) majors … but – If the class is too crowded for you, or if you can't make the worthwhile even if you don’t take another structured office hours (W 7-8 or 8-9), or if PS0 is too CS course confusing, drop CS150 now and take it later – If you are in the class now and you drop it now but plan to take it later, I will write you a note to skip you past the waitlist later #33 #34 First Main Theme: What is the longest word Recursive Definitions in the English language? Can you think of one longer than “ boustrophedon ” ? From Greek βουστροφηδόν ("ox-turning"—that is, turning like oxen in ploughing), it is an ancient way of writing manuscripts and other inscriptions. Ancient Greek boustrophedon inscription, Gortyn code, Crete, 5th c. B.C #35 #36