Week 11 Nov 17

Lists of Lists of Lists of …

Firstly, we should know what recursion means "A common method of simplification is to divide a problem into subproblems of the same type. As a computer programming technique, this is called divide and conquerand is key to the design of many important algorithms. Divide and conquer serves as a top-down approach to problem solving, where problems are solved by solving smaller and smaller instances. A contrary approach is dynamic programming. This approach serves as a bottom-up approach, where problems are solved by solving larger and larger instances, until the desired size is reached".(http://en.wikipedia.org/wiki/Recursion#Recursion_in_computer_science)

In last few weeks, we already learn the recursion tree, 

today I learn the recursion number lists

From notes there is an example:

>depth (list (list (list 1
                         2)
                   3)
             (list 4)))

>3

The answer is 3 that because:

*(list 1 2) and (list 4) is one 

(list(list 1 2) 3 (list 4 ))is two

(list (list (list 1 2) 3 (list 4 ))) is three

* importantly: lists of lists of lists… are a inclusion relation and not a coordinating relation

Also, we have other method to get the answer 3 that is:

(define (depth lol)
  (cond [(list? lol) (+ 1
                        (apply max
                               (map depth lol)))]
        [else 0]))

By the way, we have a second project in this week and due in early december.
I will know the second term test marks in Friday and I think I will not get a high mark TT

week 2 suptember 16

Lets introduce some basic knowledges :

• Flip-horizontal: a picture change from left to right 
  
• Flip-vertical: a picture change from top to bottom 
  
• above: this is hard to describe so I give you a example : 

>(Above ◆ ♠ ๑ )

  ◆

  ♠

 ๑

• beside:   

>(beside ◆ ♠ ๑ )

  ◆♠๑ 

• add:

>(+ 10 2)

  12

• minus:

>(- 10 2)

  8

• times:

>(* 1 2 3 4)

  24

Sorry I'm late to write earliest blog ^^

Week 10 Nov 10

Last week we have a term test 2 so I prepare for this term test.

Decimal notation and Binary represention :

Decimal notation- It's a math system about 10

I find decimal notation's history on Wikipedia:

Eg: Lbn Laban addition
6425
839

Eg: Sun Zi division

Binary represention-

I recall the term test 2 question and there is a calculation method:

Add: 

00+00=00

00+01=01

01+00=01

01+01=10

When we meet 01+01 we need to carry a 1.

Such as:

To summary, there are the decimal and the binary but there still has an interesting rule that are 

from decimal to binary and from binary to decimal.

Eg: 

Eg: 

All the picture are from internet 

Nov 3 week 9

In the first term test, there is a kind of built-in values:

Number-Boolean 

Image-image

Now I know that called The DATA-TYPES

• Number
• Image
• Boolean
• String
• List
• Color

I guess it Will appear in the second term test too!!!

Here is an example,

There are two people 

Lucy LuLu 1990

George Brown 1991

(define Lucy ( list "Lucy LuLu" 1990))

(define George (list "George Brown" 1991))

(Define person-name first)

(define person-birth-year second）

Lucy

"Lucy LuLu" 1990





Define-strict
I find a picture that about check-expect

Week-October 27

Last week we learn how to make some beautiful colours for a picture.

Firstly,
The range among red green and blue are (range 0 256 1)

such as:

So… Here is a question, why?

Prof. give us a website and that says:"Additive color is color created by mixing light of two or more different colors. Red, green, and blue are the additive primary colors normally used in additive color system. "(https://en.wikipedia.org/wiki/Additive_color)

Example 1:

(square 50 "solid" (make-color 255 255 0))

We can get a yellow square

…

There are all the possibilities

I think these just a warm up for colour - -

By the way, I do not know how to write last week quiz, I feel so sad.

I will learn PDF 1 2 as soon as possible.