Introduction to Computing
Using Matlab
CS 1112 Fall 2013
(CS1142)
Dr. K.-Y. Daisy Fan
http://www.cs.cornell.edu/courses/cs1112/
Todays lecture
An illuminating problem
CS1112 philosophies & syllabus
What is computer programming?
Choosing between CS1112 & CS1110
Course logistics/policies (highlights)
How about CS1115? Introduction to
Computational Science and Engineering Using
Matlab Graphical User Interfaces
Lecture 1
An illuminating problem: computing square roots
Suppose A > 0
Observation: If A is the area of a square, then I can just
measure the side lengththat is A
Idea: Make a square with area A
Real task: Make a sequence of increasingly square
rectangles, each with area A
Lecture 1
How to make a rectangle more square?
If a square and a rectangle both have area A
then A is between the length and width of the
rectangle
Lecture 1
An improvement strategy
A/L
Current:
L
Recipe:
Lnew = (L + A/L) / 2
The average of
the length and
width.
A/Lnew
Next:
Lnew
A Matlab program to make increasingly square rectangles
% The first rectangle...
L1 = A;
W1 = 1;
% The second rectangle...
L2 = (L1+W1)/2;
W2 = A/L2;
% The third rectangle...
L3 = (L2+W2)/2;
W3 = A/L3;
% and so on...
Lecture 1
Some conclusions from square root finding problem
It paid to have a geometric sense
A complicated computation was reduced to a
sequence of elementary calculations
A program is like a formula (or sequence of
formulas)
Lecture 1
11
Course Goals
Develop your computational senses, senses that
you need in computer problem-solving
Develop a facility with the Matlab programming
environment
Lecture 1
12
A sense of geometry
Lecture 1
13
A sense of complexity
What is the best
itinerary to visit
Boston, Miami, LA,
Dallas?
3! = 6 possibilities
Add Seattle, NYC
Austin, Denver
7! = 5040
If a computer can process 1 billion itineraries a second,
how long does it take to solve a 100-city problem?
Lecture 1
14
A sense of complexity
What is the best
itinerary to visit
Boston, Miami, LA,
Dallas?
3! = 6 possibilities
Add Seattle, NYC
Austin, Denver
7! = 5040
If a computer can process 1 billion itineraries a second,
how long does it take to solve a 100-city problem?
About a century
A sense of approximation & error
1/3 = .33333
Lecture 1
16
A sense of randomness and probability
Random walk
Brownian motion in water
Lecture 1
17
Course Goals
Develop your computational senses, senses that
you need in computer problem-solving
Develop a facility with the Matlab programming
environment
Lecture 1
18
Computer problem-solving
Key: Algorithmic thinking
Algorithm:
A step-by-step procedure that takes you from a
prescribed set of inputs to a prescribed set of
outputs
Program:
The algorithm expressed in a specific language, e.g.,
Matlab
Lecture 1
19
Computer problem-solving Programming
Developing instructions for the computer to
execute (in order to solve some problem)
The steps must be logical
Use a particular language and follow the rules of the
language (grammar/syntax)
Lecture 1
20
Example: Adding songs from the internet to your music library
Find a website with MP3 or other audio files
Register with the music site, if required for music
downloading. (Dont steal music.)
Click on the music file to download it onto your
computer
Drag the file to your library
Reference: iTunes
Lecture 1
21
Example: Adding songs from the internet to your music library
Drag the file to your library
Click on a music file to download it onto your
computer
Find a website with MP3 or other audio files
Register with the music site, if required for music
downloading. (Dont steal music.)
Lecture 1
22
Example: Adding songs from the internet to your music library
Find a website with MP3 or other audio files
Register with the music site, if required for music
downloading. (Dont steal music.)
Click on the music file to download it onto your
computer
Drag the file to your library
Reference: iTunes
Lecture 1
23
Example: Adding songs from the internet to your music library
Find a website with MP3 or other audio files
Register with the music site, if required for music
downloading. (Dont steal music.)
Click on the music file to dowNload it onto your
computer
file Drag your librAry to
Lecture 1
24
Computer programming is
a tool used by computer scientists, engineers, and
other professionals
not all of computer science
Think about astronomy: Telescope is a tool used
by astronomers; astronomy is not about
telescopes
Lecture 1
25
Matlab is the vehicle we use
With the Matlab environment, you can easily
Develop programs
Display results & ideas graphically
Interact with large data sets (process text,
image, and other files)
Matlab has extensive libraries of mathematical,
statistical, simulation, and other tools. It is heavily
used in engineering & sciences, both in industry and
academia.
Lecture 1
28
Engineering students take one of these courses:
CS1112 this course, Matlab
CS1115 Matlab + GUI
CS1110 Python
Each course satisfies the Engineering Computing
Requirement. In 1112 you will learn procedural
programming in depth and be introduced to objectoriented programming.
Each course can serve as the prerequisite for
CS/ENGRD 2110 Object-Oriented Programming &
Data Structure
Lecture 1
29
CS1112 has a focus on computational science & engineering
Approximation, randomness,
model building, sensitivity of models
Lecture examples and homework illustrate above
themes
Edge detection
Ranking web pages
Congressional apportionment
Lecture 1
31
Some past programming assignments
Draw the random Mondrian
Find the US population center
from census data
Organize protein data using
structure arrays
Mozarts musical dice game
Draw the Betsy Ross Flag
Pyramid of Khufu, Egypt Scale is 5.54 feet per unit length on axes
Select a path using multiple mouse clicks. Click outside the map to stop.
Total distance: 8379.3 feet
100
200
300
400
500
Path distance tool
(like that in Google Earth)
600
700
Root finding tool
800
900
Lecture 1
100
200
300
400
500
600
700
800
900
32
1000
CS1110 Now in Python
Switched from Java to Python because Python is a
friendlier and more modern object-oriented
language.
Python is more relevant to non-computer
scientists than Javanumerical libraries are
available
Matlab and Python are just different vehicles we
Conducive to discussion of design
use to travel the computational landscape.
Different scenery along the way
Both vehicles get you there
Lecture 1
33
CS1112
No prior
programming
experience
One semester of
Calculus
Focus on
computational
science & engineering
Matlab
CS1110
Lecture 1
No prior
programming
experience
No Calculus
Focus on software
development
Python
35
CS1115 Intro to Computational Science & Engineering
Using Matlab Graphical User Interfaces
Teaches the same programming concepts as CS 1112 but
there is a semester-long thread that is concerned with
Graphical User Interfaces (GUIs).
Compared to CS 1112, there is slightly more emphasis
on the connection between math and computing.
Assumes Calculus I and some programming experience
making it possible to spend more time on interesting
applications and CS concepts.
Much smallerabout 20 students. The lecture is more
like a discussion section.
Lecture 1
36
CS1112 requirements
Attend lecture
Attend discussionget individual attention/help on
weekly exercises!
Monitor course announcements on website
Do homework: best 5 of 6 programming projects
Take 2 prelims and a final exam at their scheduled times
Answer in-class quizzes (use your clicker)
Adhere to the Code of Academic Integrity
Lecture 1
41
Grading
Best five of six projects (25%)
Discussion exercises (4%)
In-class quizzes (1%)
Prelim 1 (20%)
Prelim 2 (20%)
Final exam (30%)
Lecture 1
42
Course Materials
Insight Through Computing
A Matlab introduction to Computationals Science
and Engineering
An iClicker clicker
MATLAB Student Version (2008 or
later) optional because you can use
it in the public labs
Lecture 1
43
Consulting & Computing
Consulting in ACCEL Green Room (Engineering
Library, Carpenter Hall). Check course website
for hours.
Some public labs that have Matlab:
Upson B-7
ACCEL
(Carpenter Hall, former Engrg Lib)
North campus: RPCC
Lecture 1
44
What to do now?
Pick a course
Take CS1112, CS1110, or CS1115
(add/drop: lecture and discussion and AEW)
Check course website
Start reading (see listing on course website)
Attend discussion in the lab (Upson B7) on
Tues/Wed
You must attend the discussion in which you are
enrolled!
Lecture 1
45
CS1112 Discussion Sections
Sec #
Time
Room
201
T 12:20-1:10p
UPS B7 Right & HLS 401
202
T 1:25-2:15p
UPS B7 Right & HLS 401
203
T 2:30-3:20p
UPS B7 Right & HLS 401
204
T 3:35-4:25p
UPS B7 Right & HLS 401
205
W 10:10-11:00a
UPS B7 Right & HLS 401
206
W 11:15a-12:05p
UPS B7 Right & HLS 401
207
W 12:20-1:10p
UPS B7 Right & HLS 401
208
W 1:25:2:15p
UPS B7 Right & HLS 401
209
W 2:30-3:20p
UPS B7 Right & HLS 401
210
W 3:35-4:25p
UPS B7 Right & HLS 401
Discussions are held in UPS B7 the first two weeks
Lecture 1
48
