Definition of a function and a transform

1. Definition of a function: a function is a mapping of one set of numbers to another set of numbers. The first set is called the domain and the other set is called the co-domain. A function has to satisfy two properties.

The first one is that every element in the domain must respond to an element in the co-domain.

The second is that no two elements in the co-domain respond to the same element in the domain.

2. Definition of a transform: a transform is the mapping of a set of functions to another set of functions.

Object oriented programming 1 in java: objects and methods

I/ Declare variables and initialize string objects

1. String s1;// String is a class
2. String s1 = new String(); // create an empty string s1
3. String s1 = "Whatever"; // every string is an object
4. String s2 = s1; // s2 references to a box (object) that has a content of "Whatever"
5. String s2 = new String(s1);

II/ Methods

1. String s3= s1.Uppercase() // s3 references to a box that has a content of "WHATEVER"

How to buy a mutimedia projector?

1. Brightness: 2000 ANSI lumens or more
2. Contrast: 2000:1 or more
3. Aspect Ratio - 4:3 ; 16:9
4. Bulb time: 6000 hours or more
5. XGA or at least SVGA resolution (800 x 600)
6. Display color support: 24-bit (16.7 million colors)
7. Zoom: digital and optical
8. Project TV, DVD, PC and laptop
9. Price: less than $A1000
10. Supports HD signals including 720p and 1080i
11. Minimum image size (diagonal): 1m and maximum image size: 7m
12. Minimum screen distance: 2m and maximum screen distance: 6m
13. Weight: 5kg or less
14. Technology: DLP (digital light processing), 3LCD
15. Hardware platform: PC and Mac
16. Audible noise: 22dB or less
17. Projector types: business or home use
18. Brands: viewsonic, benq, acer, nec, sharp, panasonic, epson, sanyo, hp, jvc, toshiba, optoma
19. Possible products: TOSHIBA TDP SP1 DLP Projector ($A600) for business, BENQ MP612 ($800) for home use