Android Phones

What is Android?

Android is the name of the software that an increasing number of today’s phones run on. It’s developed by Google and comes with a range of Google features, most notably Search and Maps, installed as standard.

This means you can easily search for information on the web and for directions from your phone, as you would on your computer. This is handy for checking up on things like train times and getting directions when out and about.
You can also access other Google services, like Gmail, Google Earth, YouTube and Google Calendar on an Android phone.
What can an Android phone do?

Android phones are highly customisable and as such can be altered to suit your tastes and needs. You can check your Facebook and Twitter profiles through a variety of apps making it ideal for social networking. Through the calendar you can set reminders from your desktop or your phone and on the latest version of Android you can send links to and from your computer and vice versa.

Another neat feature of Android is that it automatically backs up your contacts for you. When you set up an Android phone you’ll need to create a Google Account or sign in with an existing one. Every time you save a number to the address book of your Android phone it will be synced to your Google Account.
The benefit of this is if you lose your phone all of your numbers will be saved. The next time you get an Android phone and sign in with your Google Account, all of your contacts and friends numbers will be displayed in your new phone’s address book.
What apps can I get on an Android phone?
There is a huge range of apps and games available to download from the Android Market. There are camera apps that allow you to take pictures with artistic effects and filters on them and music players which allow you to import MP3s from your and create playlists.
You can customise the appearance of your Android phone with a number of wallpapers based on pictures you’ve taken yourself or downloaded from the web.
There are also various on screen widgets to download which allow you to access and reconfigure the settings of your phone. You can pretty much create your own system of shortcuts and menus to suit you.
Popular games available for Android phones now include Angry Birds, Fruit Ninja, Wordfeud and Drop 7.
How can I get apps on an Android phone?
The majority of Apps are downloaded from the Android Market (the equivalent of Apple’s iTunes App Store). Most of these are free but there are some premium apps as well that you’ll have to pay for.
You’ll have to set up an account with Google Checkout in order to pay for apps. You can pay either by debit or credit card. This takes less than five minutes to set up and is best done from your computer.
Some developers choose to make their apps available to download freely outside the Android Market and directly from their own sites. In order to download these you'll have to change some settings on your phone before visiting the site on your Android phone’s web browser.
What does an Android phone look like?

Android phones come in many different shapes, colours and sizes. Some have super-fast processors, some have powerful cameras and some have slide-out Qwerty keypads.

All Android phones prominently feature a large touchscreens. The size of the screen varies, but most of them measure at least 3-inches diagonally.
Popular Android phones include the HTC Desire (3.7-inch screen), Motorola Milestone (3.7-inch screen), Samsung Galaxy S (4-inch screen) and the Sony Ericsson Xperia X10 (4-inch screen). The Dell Streak has a huge 5-inch touchscreen and is currently the biggest Android phone in terms of dimensions and screen size.
So who makes Android phones?
Every handset maker is free to make an Android phone if they want to. As well as the aforementioned HTC, Motorola, Samsung and Sony Ericsson, LG, Acer, Dell and Huawei have all made Android phones. There isn’t however a Nokia or a BlackBerry Android phone and there probably won’t be.
Does Google make any Android phones?
Google makes the software not the hardware. One phone - the Google Nexus One - is branded as “the Google Phone” but is actually made by HTC, who make other Android phones such as the HTC Desire and HTC Legend. It is considered to be the flagship Android phone, even though some Android phones have bigger screens and better cameras.
Of all of the Android phones, the Google Nexus One is currently always the first to receive new Android updates.
Do Android updates cost anything?
Android updates are free. The updates bring a number of new features and changes to Android each time. Generally though, with each update the speed and overall performance of Android is improved upon.
Most of the high-end Android phones are scheduled to receive updates first. Most Android phones will have at least one update during their life cycle, with some having two.
How do I get an update?
Android updates are normally received OTA (over the air), that is, sent directly to your Android phone. Normally, once your Android phone or tablet is due to get an upgrade, you'll see a notification at the bar at the top of the screen. Then you'll be prompted to connect to Wi-Fi to avoid incurring extra data charges - updates can be quite big.
Updates are generally one-stage processes and relatively straightforwards, but in some cases you may need to back up/save any photos or apps you've downloaded before updating.
In some cases, as with Samsung's Android phones like the Galaxy S, you'll need to install the Kies program in order to receive Android updates.

Conditional Asymptotic Notations

                                 Asymptotic Notation
Asymptotic notation deals with the behaviour of a function in the limit,that is, for sufficiently large values of its parameter. Often, when analysing the run time of an algorithm, it is easier to obtain an
approximate formula for the run-time which gives a good indication of the algorithm performance for large problem instances. For example, suppose the exact run-time T(n) of an algorithm on an input of size n is T(n) = 5n2 + 6n + 25 seconds. Then, since n is ≥0, we have n2 ≤ T(n) ≤ 6n2 for all n≥9. Thus we can say that T(n) is roughly proportional ton2 for sufficiently large values of n. We write this as T(n)∈ Θ(n2 ), or say that“T(n) is in the exact order of
n2”.
Definition:

Let f(n) be an arbitrary function from the natural numbers N = {0,1,2,…}to the set R≥ 0 of nonnegative reals. Let R+ denote the set of positive reals.  define O( f (n)) = {t : N →R≥0 : ∃c ∈ R+ ∃n0 ∈ N ∀n ≥ n0 (t(n) ≤ cf (n))} In other words, O( f (n)) - pronounced “big Oh of f(n)” – is the set of all functions t : N →R≥0 such that t(n) ≤ cf(n) for all n ≥ n0 for some positive real constant c and integer threshold n0 . Notice that O( f (n)) is a set, so that we refer to a function t(n) as being in the order of f(n) if t(n)∈ O( f (n)).
This differs from the way in which O( f (n)) is sometimes defined elsewhere in the literature.
Example:

Suppose that an algorithm takes in the worst case 
t(n) = 27n2 + 355 113 n +12 microseconds on a certain computer to solve an instance of size n of a problem. We can show that t(n) is in the order of  n2 by the following argument: t(n) = 27n2 + 355 113 n +12 ≤ 27n2 + 355 113 n2 +12n2 (provided n ≥1) = 42 16
113 n2 Thus there exist constants n0 (=1) and c(= 42 16
113) such that t(n) ≤cf(n) for all n ≥ n0 . That is,
t(n)∈ O(n2) .
Conditional asymptotic notation:

Many algorithms are easier to analyse if initially we restrict our attention to instances whose size satisfies a certain condition, such as being a power of 2. Consider, for example, the divide and conquer algorithm for multiplying large integers that we saw in the Introduction. Let n be the size of the integers to be multiplied. The algorithm proceeds directly if n = 1, which requires a microseconds for an appropriate constant a. If n>1, the algorithm proceeds by multiplying four pairs of integers of size n/2 (or three if we use the better algorithm). Moreover, it takes a linear amount of time to carry out additional tasks. For simplicity, let us say that the additional work takes at most bn microseconds for an appropriate constant b.
[Note: In actual fact, the recursive algorithm carries out one multiplication of two n/2 digit integers, one multiplication of two n/2 digit integers, and two multiplications of a n/2 digit integer and a n/2 digit integer. For simplicity we shall assume that the algorithm always carries out four multiplications of two n/2 digit integers. It turns out that the running time of this simplified method is in the same order as the
running time of the more detailed method.] The worst case time taken by this algorithm is therefore given by the function t : N →R≥0 recursively defined by t(1) = a 
t(n) = 4t(n /2) + bn for n >1 We shall be studying techniques for solving recurrences in the next section, but unfortunately this equation cannot be handled directly by those techniques because the ceiling function n/2 is rather troublesome. Nevertheless, our recurrence is easy to solve provided we consider only the
case when n is a power of 2. In this case n/2 = n/2 and the ceiling vanishes. The techniques of the next section yield
t(n) = (a + b)n2 − bn provided that n is a power of 2. Since the lower-order term “-bn” can be neglected, it follows that t(n) is in the exact order of n2, still provided that n is a power of 2. This is denoted by t(n)∈ Θ(n2 | n is a power of 2) . More generally, let
f ,t : N →R≥0 be two functions from the natural numbers to the nonnegative reals, and let P :N →{true, false} be a property
of the integers. We say that t(n) is in O( f (n) | P(n )) if t(n) is bounded above by a positive real multiple of f(n) for all sufficiently large n such that P(n) holds. Formally, O( f (n) | P(n )) is defined as {t :N → R≥ 0 : ∃c ∈ R+ ∃n0 ∈ N ∀n ≥ n0 (P( n) →t(n) ≤ cf (n))}
The sets Ω( f (n) |P(n)) and Θ( f (n) |P(n)) are defined in a similar way. Conditional asymptotic notation is more than a mere notational
convenience: its main interest is that it can generally be eliminated once it has been used to facilitate the analysis of an algorithm. For this we need a few definitions. A function f :N → R≥ 0 is eventually nondecreasing if there exists an integer threshold n0 such that f(n) ≤ f(n+1) for all n ≥ n0 . This implies by mathematical induction that f(n) ≤ f(m) whenever m ≥ n ≥ n0 . Let b ≥ 2 be any integer. Function f is b-smooth if, in addition to being eventually nondecreasing, it satisfies the condition f (bn)∈ O( f (n)). In other words, there must exist a constant c (depending on b) such that f(bn) ≤ cf(n) for all
n ≥ n0 . A function is smooth if it is b-smooth for every integer
b ≥ 2. Most functions we are likely to encounter in the analysis of algorithms are smooth, such as log n , nlog n ,
n2, or any polynomial whose leading coefficient is positive. However, functions that grow too fast, such as nlogn ,
2n or n! are not smooth because the ratio f(2n)/f(n) is unbounded. For example (2n)log (2n ) = 2n2nlogn
which shows that (2n)log(2n ) ∉ O(nlog n ) because
2n2 cannot be bounded above by a constant. Functions that are bounded above by a polynomial, on the other hand, are usually smooth provided they are eventually nondecreasing; and even if they are not eventually nondecreasing there is a good chance that they are in the exact order of some other function that is smooth. For instance, let b(n) denote the number of bits equal to 1 in
the binary expansion of n – such as b(13) = 3 because 13 is written as 1101 in binary – and consider f (n) = b(n) + logn . It is easy to see that f(n) is not eventually nondecreasing – and therefore it is not smooth – because b(2k −1) = k whereas b(2k ) =1 for all k. Nevertheless, f (n) ∈ Θ(log n) , a smooth function.
A useful property of smoothness is that if f is b-smooth for any specific integer b ≥ 2, then it is in fact smooth. To prove this, consider any two integers a and b not smaller than 2. Assume that f is b-smooth. We must show that f is a-smooth as well. Let c and
n0 be constants such that f(bn) ≤ cf(n) and f(n) ≤ f(n+1) for all
n ≥ n0 . Let i= logb a . By definition of the logarithm , a = blogb a ≤ blog b a = bi . Consider any n ≥ n0 . It is easy to show by mathematical induction from b-smoothness of f that f (bin) ≤ c i f (n) . But f (an) ≤ f (bin) because f is eventually nondecreasing and bin ≥ an ≥ n0 . It follows that f (an) ≤ cˆ f (n) for cˆ = ci , and thus f is a-smooth.

Shorcuts Keys

Shortcut Key	Supported Window Versions	Short Key Description
Alt + (double-click)	95, 98, ME, NT, 2000, XP, Vista	Open Properties dialog of selected item.
Alt + Enter	95, 98, ME, NT, 2000, XP, Vista	Opens properties window of selected item.
Alt + Esc	95, 98, ME, NT, 2000, XP, Vista	Switch Between open tasks available on the taskbar.
Alt + F4	95, 98, ME, NT, 2000, XP, Vista	Close the top (focused) window.
Alt + Tab	95, 98, ME, NT, 2000, XP, Vista	Switch between open windows.
Alt + Tab + Shift	95, 98, ME, NT, 2000, XP, Vista	Switch between open windows, backward.
Ctrl + Alt + Delete (or Del)	95, 98, ME, NT, 2000, XP, Vista	Bring up the Windows Task Manager, or reboot computer.
Ctrl + Esc	95, 98, ME, NT, 2000, XP, Vista	Bring up the Windows Start menu.
Ctrl + '+' ('+' key on the keypad)	98, ME, NT, 2000, XP, Vista	Autofit the widths of all columns (if available) in current window.
Ctrl + F4	95, 98, ME, NT, 2000, XP, Vista	Close sub window/tab.
Ctrl + Tab	95, 98, ME, NT, 2000, XP, Vista	Switch between existing tabs (within a window).
Ctrl + Tab + Shift	95, 98, ME, NT, 2000, XP, Vista	Switch between existing tabs (within a window), backward
F1	95, 98, ME, NT, 2000, XP, Vista	Open Help for Windows or focused application.
F2	95, 98, ME, NT, 2000, XP, Vista	Rename.
F3	95, 98, ME, NT, 2000, XP, Vista	Find/Search.
F4	95, 98, ME, NT, 2000, XP, Vista	Select drives or display the list of drives
F5	95, 98, ME, NT, 2000, XP, Vista	Refresh.
F6	95, 98, ME, NT, 2000, XP, Vista	Switch focus to the address bar (if exists).
F10	95, 98, ME, NT, 2000, XP, Vista	Switch focus to the top menu bar.
Shift + F10	95, 98, ME, NT, 2000, XP, Vista	Same as mouse right-click on the select item.
Print Screen	95, 98, ME, NT, 2000, XP, Vista	Capture a screenshot of the entire desktop to clipboard.
Print Screen + Alt	95, 98, ME, NT, 2000, XP, Vista	Capture a screenshot of just the top(focused) window to clipboard.
Shift + Delete (or Del)	95, 98, ME, NT, 2000, XP, Vista	Permanently delete selected file(s)/folder(s) (bypass recycle bin)
Shift (hold while inserting an audio CD to drive)	95, 98, ME, NT, 2000, XP, Vista	Prevent autoplay.
* (keypad) on Windows Explorer.	95, 98, ME, NT, 2000, XP, Vista	Expand all sub-directories from the selected item.
+ (keypad) on Windows Explorer.	95, 98, ME, NT, 2000, XP, Vista	Expand only the first level of selected item.
- (keypad) on Windows Explorer.	95, 98, ME, NT, 2000, XP, Vista	Collapse

Shortcut Keys	Description
WINDOWS-KEY	Bring up the Windows Start menu.
WINDOWS-KEY + F1	Bring up the Windows Help.
WINDOWS-KEY + e	Open Microsoft Explorer.
WINDOWS-KEY + f	Windows Search.
WINDOWS-KEY + Ctrl + f	Search for computers
WINDOWS-KEY + d	Minimizes all and bring up desktop, or restore all
WINDOWS-KEY + l	Lock the computer (Windows XP & newer).
WINDOWS-KEY + m	Minimizes all windows.
WINDOWS-KEY + Shift + M	Restore all. Opposite with WINDOWS-KEY + M and WINDOWS-KEY + D.
WINDOWS-KEY + r	Open the run window.
WINDOWS-KEY + u	Utility Manager.
WINDOWS-KEY + Tab	Cycle through the programs on task bar.
WINDOWS-KEY + Pause/Break	Open the System Properties window.

Touch Screen Mechanism

There are three different systems used in the mechanism of touch screen.

1. Resistive System

In this resistive mechanism of touch screen two sheets are used one is conductive and the other is resistive. Both cover the top glass panel. There is a space between two sheets so that current pass when it is toggle. Now touching the screen forced both layers to contact at a certain point. This contact of both layers cause in the electric field a variation which is informed to the main system that a touch is felt. OS transcribe the touch into desired action.   

2. Capacitive System

Second method utilizes in touch screen is capacitive. To understand this mechanism, it is better to know about human biology first. Many chemical reactions take place in our body and electricity produced in result to perform different functions. That is the reason why human heart is recharged with electric shocks for the recovery. Considering human body a cell you can better understand this phenomenon. In this system an electric charge sheet (capacitor) is directly placed on the glass. When we touch the screen with finger, a static charge produces and reacts with the capacitor (electric charge sheet). As the touch screen works due to electric current develop when touches the finger.

3. Surface Acoustic Wave System

This type of touch screen works with the help of wave energy. This enables a touch to transform into another form of energy and deliver the command which in response perform the desired action. A pair of transducers is placed on glass plate sides. In the glass plate there are reflectors. On touching the screen wave produced and which transforms into energy for fulfilling the command. It tells where on the screen touch is detected.
Important Information

First both techniques utilize the electric charge mechanism to develop a touch screen system but the third uses wave system and do not need a metallic plate. This surface acoustic wave system is free of electric field that’s why there is no resistance in the way of light dispersal. This 100 percent light emission gives extra clarity to the screen which is not possible in first two mechanisms. Resistive system enables 75 % of light emission. However capacitive system allows 90% of light emission so better than resistive. Capacitive system enables sharp image as compared to resistive system even then no comparison with the image quality if surface acoustic system.