Start to Code. Instructor: Xiao Liu

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1 Start to Code Instructor: Xiao Liu

2 What does a Computer do Fundamentally Calculation - Moore s Law Storage - Different levels What kind of calculations? +, -, *, / Turing Machine Similarly, the symbol read is a 1, so we repeat the same instructions. Symbol read Write instruction Move instruction Blank None None 0 Write 1 Move tape to the right 1 Write 0 Move tape to the right

3 Turing Machine Answer: Just change the final q0 into q1. Why?

4 Turing Complete In computability theory, a system of data-manipulation rules (such as a computer's instruction set, a programming language, or a cellular automaton) is said to be Turing complete or computationally universal if it can be used to simulate any single-taped Turing machine.

5 Today PiE-LOGO First Try Move the Turtle Attributes can be modified Basics in Programming

6 Let s Try PiE-LOGO

7 PiE-LOGO A triangle on the screen to be moved

8 PiE-LOGO A triangle on the screen to be moved The trace left behind will form a graphic.

9 PiE-LOGO A triangle on the screen to be moved The trace left behind will form a graphic.

10 PiE-LOGO A triangle on the screen to be moved You can give it commands in English

11 PiE-LOGO A triangle on the screen to be moved You can give it commands in English Forward 150 steps Turn left 90 degrees

12 PiE-LOGO A triangle on the screen to be moved You can give it commands in English The commands should be imperative

13 PiE-LOGO A triangle on the screen to be moved You can give it commands in English The commands should be imperative declarative knowledge is statements of fact. someone will win a Google Cardboard before class ends imperative knowledge is a recipe or how-to. Students sign up for raffle Ana opens her IDE Ana chooses a random number between 1st and nth responder Ana finds the number in the responders sheet. Winner!

14 Programming Language - Syntax English Grammar "cat dog boy" -> not syntactically valid "cat hugs boy" -> syntactically valid Programming Language Syntax 150 Go -> not syntactically valid Forward 150 steps -> syntactically valid

15 Programming Language - Static Semantics English "I are hungry" -> syntactically valid -> but static semantic error Programming Language Forward hi steps -> syntactically valid -> but static semantic error

16 Programming Language - Semantics Semantics is the meaning associated with a syntactically correct string of symbols with no static semantic errors English: can have many meanings "Flying planes can be dangerous" Programming languages: have only one meaning but may not be what programmer intended

17 Try Move the Turtle

18 Lab 2: Task Steps 141 Steps

19 Attributes can be modified

20 Lab 2: Task Steps 140 Steps

21 Loop

22 Lab 2: Task Steps 141 Steps

23 Function & Script

24 Lab 2: Task 3

25 What is a Recipe Sequence of simple steps Flow of control process that specifies when each step is executed A means of determining when to stop

26 Lab 2: Task 4 - Example (1)Now, can you draw an octagon(8 sides)? How about (2)decagon(10 sides) and (3)dodecagon(12 sides)?

27 Lab 2: Code Revision?

28 Lab 2: Code Revision

29 Lab 2: Code Revision 45

30 Lab 2: Code Revision?

31 Lab 2: Code Revision?

32 Lab 2: Task 5 - Example (4)Nine-pointed star?how about (5)Twelve-pointed star? Hint: The angle turned in each round has relationship with how many points and 180.

33 Lab 2: Code Revision

34 Code Philosophy Code is about Math! But not always Math!

WELCOME! (download slides and.py files and follow along!) LECTURE 1

WELCOME! (download slides and.py files and follow along!) 6.0001 LECTURE 1 6.0001 LECTURE 1 1 TODAY course info what is computation python basics mathematical operations python variables and types NOTE: