functions - university of california, berkeleycs61a/fa19/assets/...• lots of other stuff: homework...

Functions

About the Course

The 61A Community

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The 61A Community

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57 teaching assistants (TAs), formally known at Berkeley as GSIs or UGSIs:

The 61A Community

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• Teach lab & discussion sections

The 61A Community

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• Teach lab & discussion sections• Hold drop-in office hours

The 61A Community

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• Lots of other stuff: develop assignments, grade exams, etc.

The 61A Community

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50+ mentors:

The 61A Community

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50+ mentors:

• Teach mentoring sections

The 61A Community

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50+ mentors:


• Hold drop-in office hours

The 61A Community

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50+ mentors:



• Lots of other stuff: homework parties, mastery sections, etc.

The 61A Community

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50+ mentors:




200+ academic interns help answer individual questions during lab

The 61A Community

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50+ mentors:




200+ academic interns help answer individual questions during lab

2,000 fellow students make CS 61A unique

Parts of the Course

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Parts of the Course

Lecture: Videos posted to cs61a.org before each live lecture

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Parts of the Course


Lab section: The most important part of this course (next week)

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Parts of the Course



Discussion section: The most important part of this course (this week)

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Parts of the Course




Staff office hours: The most important part of this course (next week)

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Parts of the Course





Online textbook: http://composingprograms.com

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Parts of the Course






Weekly homework assignments, three exams, & four programming projects

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Parts of the Course







Lots of optional special events to help you complete all this work

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Parts of the Course







Lots of optional special events to help you complete all this work

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Everything is posted to cs61a.org

Announcements

An Introduction to Computer Science

What is Computer Science?

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!7

The study of


!7

What problems can be solved using computation,The study of


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What problems can be solved using computation,How to solve those problems, andThe study of


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What problems can be solved using computation,How to solve those problems, andWhat techniques lead to effective solutions

The study of


Systems

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The study of


Systems

Artificial Intelligence

!7


The study of


Systems


Graphics

!7


The study of


Systems


Graphics

Security

!7


The study of


Systems


Graphics

Security

Networking

Programming Languages

Theory

Scientific Computing

...

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The study of


Systems


Graphics

Security

Networking


Theory


...

!7

Decision Making


The study of


Systems


Graphics

Security

Networking


Theory


...

!7

Decision Making

Robotics


The study of


Systems


Graphics

Security

Networking


Theory


...

!7

Decision Making

Robotics

Natural Language Processing


The study of


Systems


Graphics

Security

Networking


Theory


...

!7

Decision Making

Robotics


...


The study of


Systems


Graphics

Security

Networking


Theory


...

!7

Decision Making

Robotics


...


The study of

Answering Questions


Systems


Graphics

Security

Networking


Theory


...

!7

Decision Making

Robotics


...


The study of

Answering Questions

Translation


Systems


Graphics

Security

Networking


Theory


...

!7

Decision Making

Robotics


...


The study of

Answering Questions

Translation

...

What is This Course About?

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A course about managing complexity

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Mastering abstraction

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Programming paradigms

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An introduction to programming

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Full understanding of Python fundamentals

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Combining multiple ideas in large projects

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How computers interpret programming languages

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Different types of languages: Scheme & SQL

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Different types of languages: Scheme & SQL

A challenging course that will demand a lot of you

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Alternatives to CS 61A

CS 10: The Beauty and Joy of Computing

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Designed for students without prior experience

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A programming environment created by Berkeley, now used in courses around the world and online

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An introduction to fundamentals (& Python) that sets students up for success in CS 61A

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Fall 2018: Dan Garcia

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25 seats available

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25 seats available

More info: http://cs10.org/fa18/

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Data Science 8: Foundations of Data Science

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Fundamentals of computing, statistical inference, & machine learning applied to real-world data sets

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More statistics than computer science

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Great programming practice for CS 61A

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Listed as CS C8

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Listed as CS C8

This semester it's full

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Listed as CS C8

This semester it's full

More info: http://data8.org/fa18

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Course Policies

Course Policies

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Course Policies

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Learning

Course Policies

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Learning

Community

Course Policies

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Learning

Course Staff

Community

Course Policies

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Learning

Course Staff

Details...

http://cs61a.org/articles/about.html

Community

Collaboration

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Collaboration

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Asking questions is highly encouraged

Collaboration

•Discuss everything with each other; learn from your fellow students!

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Collaboration


•Some projects can be completed with a partner

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Collaboration



•Choose a partner from your discussion section

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Collaboration




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The limits of collaboration


Collaboration




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• One simple rule: Don’t share your code, except with your project partner



Collaboration




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• Copying project solutions causes people to fail the course



Collaboration




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• We really do catch people who violate the rules, because...



Collaboration




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•We also know how to search the web for solutions



Collaboration




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•We use computers to check your work



Collaboration




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•We use computers to check your work



Build good habits now

Expressions

Types of expressions

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An expression describes a computation and evaluates to a value

18 + 69


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18 + 696

23


!16


18 + 696

23

p3493161


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18 + 696

23

p3493161

sin⇡


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18 + 696

23

p3493161

sin⇡

|� 1869|


!16


18 + 696

23

p3493161

sin⇡

100X

i=1

i

|� 1869|


!16


18 + 696

23

p3493161

sin⇡

100X

i=1

i

|� 1869|

✓69

18

◆


!16


18 + 696

23

p3493161

sin⇡

f(x)100X

i=1

i

|� 1869|

✓69

18

◆


!16


18 + 696

23

p3493161

sin⇡

f(x)100X

i=1

i

|� 1869|

✓69

18

◆

2100


!16


18 + 696

23

p3493161

sin⇡

f(x)100X

i=1

i

|� 1869|

✓69

18

◆

2100

log2 1024


!16


18 + 696

23

p3493161

sin⇡

f(x)100X

i=1

i

|� 1869|

✓69

18

◆

2100

log2 1024

7 mod 2


!16


18 + 696

23

p3493161

sin⇡

f(x)100X

i=1

i

|� 1869|

✓69

18

◆

2100

log2 1024

7 mod 2 limx!1

1

x


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Call Expressions in Python

All expressions can use function call notation

(Demo)

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Anatomy of a Call Expression

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add ( 2 , 3 )


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add ( 2 , 3 )

Operator


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add ( 2 , 3 )

Operator Operand Operand


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add ( 2 , 3 )


Operators and operands are also expressions


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add ( 2 , 3 )



So they evaluate to values


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Evaluation procedure for call expressions:

add ( 2 , 3 )





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add ( 2 , 3 )



1. Evaluate the operator and then the operand subexpressions



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add ( 2 , 3 )



1. Evaluate the operator and then the operand subexpressions

2. Apply the function that is the value of the operator

to the arguments that are the values of the operands


mul(add(4, mul(4, 6)), add(3, 5))

Evaluating Nested Expressions

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mul(add(4, mul(4, 6)), add(3, 5))


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mul

mul(add(4, mul(4, 6)), add(3, 5))

add(4, mul(4, 6))


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mul

mul(add(4, mul(4, 6)), add(3, 5))

add(4, mul(4, 6))


!19

mul

add

mul(add(4, mul(4, 6)), add(3, 5))

add(4, mul(4, 6))


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mul

add 4

mul(add(4, mul(4, 6)), add(3, 5))

add(4, mul(4, 6))


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mul

add 4

mul(4, 6)

mul(add(4, mul(4, 6)), add(3, 5))

add(4, mul(4, 6))


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mul

add 4

mul(4, 6)

mul 4 6

mul(add(4, mul(4, 6)), add(3, 5))

add(4, mul(4, 6))


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mul

add 4

mul(4, 6)

mul 4 6

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mul(add(4, mul(4, 6)), add(3, 5))

add(4, mul(4, 6))


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28mul

add 4

mul(4, 6)

mul 4 6

24

mul(add(4, mul(4, 6)), add(3, 5))

add(4, mul(4, 6))


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28mul

add 4

mul(4, 6)

mul 4 6

24

add(3, 5)

mul(add(4, mul(4, 6)), add(3, 5))

add(4, mul(4, 6))


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28mul

add 4

mul(4, 6)

mul 4 6

24

add(3, 5)

add 3 5

mul(add(4, mul(4, 6)), add(3, 5))

add(4, mul(4, 6))


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28mul

add 4

mul(4, 6)

mul 4 6

24

add(3, 5)

add 3 5

8

224mul(add(4, mul(4, 6)), add(3, 5))

add(4, mul(4, 6))


!19

28mul

add 4

mul(4, 6)

mul 4 6

24

add(3, 5)

add 3 5

8

224mul(add(4, mul(4, 6)), add(3, 5))

add(4, mul(4, 6))28mul

add 4

mul(4, 6)

mul 4 6

24

add(3, 5)

add 3 5

8


!20

224mul(add(4, mul(4, 6)), add(3, 5))


add 4

mul(4, 6)

mul 4 6

24

add(3, 5)

add 3 5

8


!20

Expression tree

224mul(add(4, mul(4, 6)), add(3, 5))


add 4

mul(4, 6)

mul 4 6

24

add(3, 5)

add 3 5

8


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Expression tree

Operand subexpression

224mul(add(4, mul(4, 6)), add(3, 5))


add 4

mul(4, 6)

mul 4 6

24

add(3, 5)

add 3 5

8


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Expression tree


Value of subexpression

224mul(add(4, mul(4, 6)), add(3, 5))


add 4

mul(4, 6)

mul 4 6

24

add(3, 5)

add 3 5

8


!20

Expression tree


1st argument to mulValue of subexpression

224mul(add(4, mul(4, 6)), add(3, 5))


add 4

mul(4, 6)

mul 4 6

24

add(3, 5)

add 3 5

8


!20

Expression tree


1st argument to mul

Value of the whole expression

Value of subexpression

Functions, Values, Objects, Interpreters, and Data

(Demo)

functions - university of california, berkeleycs61a/fa19/assets/...• lots of other stuff: homework...

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