CMSC 150 - Fall 2016- Diving into the Computer Science

Monday, November 28, 2016

Compter Graphics

What is a Computer Graphics ?

Computer Graphics are usually image data that is created using a specialized graphical hardware and software. This phrase was brought into existence the Graphics researcher Verne Hudson and William Fetter. The important topic that are a part of Computer Graphics are User Interface design, vector Graphics, Graphics processing Unit ( also known as Visual Processing Unit), 3D Modeling.
The term Computer Graphics can refer to several things:-

The manipulation of data in the form of Image using Computers.
The technology used to manipulate the image.
The sub-field of Computer Science that studies different methods of Synthesizing and Manipulating Visual Data

Concepts and Principles included in Computer Graphics

Pixels :- Pixel is a single point in an image. It is a two dimensional grid and is represented using symbols like dots and squares.
Graphics:- Graphics are visual presentations combining text and illustrations.
Primitives :- Primitives are basic units that a graphic system may combine to create complex images and models such as Character maps in 2D Video Games.
Rendering :- Rendering is the creation of a 2D Image from a 3D model using computer programs. The Rendering Program is a lighting model for computer generated Imagery
3D Projection:- 3D Projection is the method of mapping three dimensional points on a plane that is two dimensional. The use of 3D projection is wide spread in field such as Computer Graphics and Engineering.
3D Modeling:- 3D Modeling is the process of developing a mathematical representation of a three dimensional object. It can be manual or automatic.

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References

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Friday, November 18, 2016

Wildcard in Programming

What is Wildcard?

Wildcard is a symbol used to replace or represent one or two characters. There are different types of symbols used for the wildcard. Many application and Operating Systems support wildcard to search for file and directories. It helps the user to search for files with using short forms while searching for a file name. The advantage of the functions of Wildcard is that if the person doesn't remember the full name but vaguely remembers a few letters they can see all the options available with that file name and recognize the name rather which is easier than having to remember the full name.

What are the different symbols used as Wildcard Character?

There are different characters used as a Wildcard:-

PercentWildcard (%) -: The percent wildcard is used to matches characters zero or more times in the Structured Query Language (SQL). It includes the underscore symbol as well.
AsteriskWildcard(*) -: The Asterisk is used to match characters zero or more times. For example , for (comp*) all the terms starting 'comp' such as computer, complete, will be included in this.
Question MarkWildcard (?):- The question Mark is used to match a single character. For example for ("c*mp") the perfect matches would include words like camp and comp. In MS-DOS and the Windows the question mark symbol(?) matches the trailing question marks zero or one times. For example, ("si??") would also show the result sip even though it doesn't have four character. This is because it matches the trailing question mark.
Open and close Bracket Wildcard ([]) :- The open and close brackets match single characters in the range . For example, the letter f would be matched by this Wildcard but the number 8 would not be matches by this Wildcard because it is not a part of this range.

What are the programming languages that support the usage of Wildcard?

Wildcard can be used in Javascript and C++ and Structured Query Language (SQL).
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Friday, November 11, 2016

Use of Computer in Banking

The computers have taken over most of the world. As predicted by Economists, all the Routine manual and Routine Cognitive are being removed. The main reason for this to happen is the development of technology which in turn is also making dependent on Technology. Just like the fields in the world, computer Science is the also a very essential part of Banking.

What is role of computer in Banking?

The role that computer science plays in Banking are
- It makes sure that no money is being misplaced or lost in transaction.
- It has a fixed place where all the data and information about the transactions and the people involved in the transactions is storage.
- the computer helps to store more information than an entire library of books and files would have been able to store.
-With the improvement in computer a whole new kind of Banking has opened up that is completely web based. It helps you to conduct all your economic transactions sitting on the computer.
- It has made the informations about the bank for all the people more accessible.
- It has made it easier for the banks be in touch with the other branches of the bank.

Computers are essential for the Smooth function of the banking because computers are found at every stage of Banking. The smooth functioning of Banking depends on the smooth function of the ATM, the bank computer that authorizes money withdrawal, Direct Deposit depends on computerized transactions, use of the Scanner which makes transactions so much more secured, and many more just technological tools to make it easier for the Bankers
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Reference

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Friday, November 4, 2016

Computer Virus

A computer virus is a piece of code that enters the system that damages the regular working of the computer. The computer viruses are all man made and they make the computer run against your wish. The computer viruses can takes over a great space in the hard disk.The main causes for Computer viruses are:

-Infected Flash Drives or Disks

- email attachments

-unknown infected websites

-use of pirated software

What are the different types of Viruses?

The different types of viruses are
-CodeRed:-This is a worm that infected the function of the Microsoft IIS Server. This is the Virus that posed an attack on the White House's Website.

-Nimba:- It is the kind of Virus that spreads itself using different methods. It can make changes to pre-existing file, change the security system and degrades the performance of the computer

-Sircam:- This kind of virus is spread via email. It degrades the performance and also delete's the files. This kind of Virus can be sent to anyone.

- Melisa:- This is a virus that send itself to 50 people if Microsoft Outlook is installed on the device. It disables different safeguarding setting in MS Word.

- Ripper:- It corrupts the data from the hard disk

- MDMA:- It transfers between the two MS Word file in the memory.

- Concept:- This kind of virus is also spread around via email attachments. They save the file in template directories instead of storing them in their Original Locations.

How can we protect our computers from Anti-viruses?

The computer can be protected from Anti-Viruses by the following precaution
- The latest version of Anti- virus software should be installed in our computers.
-The anti-virus should be updated regularly.
-USB drive should be scanned for viruses and shouldn't be used on infected computers.
- Unauthorized or pirated software shouldn't be installed on the computer.

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References

https://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&ved=0ahUKEwjMr6jplZDQAhWBLSYKHXZgAvcQjRwIBw&url=http%3A%2F%2Fhome.bt.com%2Ftech-gadgets%2Fcomputing%2Fwhat-is-a-computer-virus-11363921495036&psig=AFQjCNEGhtr4428u9c7Td4GDVM00aojeLQ&ust=1478385437577697

http://www.byte-notes.com/what-computer-virus#simple-table-of-contents-3

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Friday, October 28, 2016

Polymorphism

In object-oriented programming, Polymorphism refers to a programming language's ability to process objects differently depending on their data type or class. In other words, It is the ability to redefine methods for derived classes. Polymorphism is considered to be a requirement of any true Object-Oriented Programming Language (OOPL). There can we several types of Polymorphism.

What are the different types of Polymorphism ?

Ad hoc polymorphism: When the function denotes different heterogeneous implementations depending on a limited range of individually specified types and combinations. Ad hoc polymorphism is supported in many languages using function overloading.
Parametric polymorphism: When code is written without mention of any specific time and thus can be used transparently with any number of new types. In object-oriented programming community, this is often known as generics or generic programming. In functional programming community, this is often simply referred to as polymorphism.
Sub typing :This is also called subtype polymorphism or inclusion polymorphism. When a name denotes instances of many different classes related by some common superclass. In the object-oriented programming community, this is often simply referred to as polymorphism.

The interaction between parametric polymorphism and sub typing that leads to the concepts of variance and bounded quantification.

When is Polymorphism useful ?

The usefulness of Polymorphism depends on the programmer's design and logic. If the programmer wants to bind your implementation at runtime then Subtype polymorphism will be useful. If you want to invoke different implementation at runtime based on the input arguments then ad-hoc polymorphism will help. If the programmer wants to write a code with a family of types, the code can ignore type specific details and just interact with the base type of family. Even though the code thinks it is using an object's class could actually be the base class or any one of its subclasses. This makes it easier the programmer to write the code and the readers to understand.Overall, polymorphism provides a powerful feature in binding the implementation at runtime and provides design extensibility.
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References

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Friday, October 21, 2016

Deadlock

Earlier the computer operating system ran only one program at a time. All the resources of the system were available to this one program. As technology developed, operating system ran multiple programs at once, interleaving them.This brought in the problem of Deadlock. Deadlock is a situation in which two computer programs share the same resources and effectively prevent each other from accessing the resources which results in both programs ceasing to function. In other words, this is a condition that occurs when two processes are each waiting for the each other to complete before proceeding and thus, the result is that both processes hang. Deadlocks mostly occur in multitasking and client/server environments.

What are the necessary conditions ?

There are four necessary conditions to achieve deadlocks :-

1) Mutual Exclusion: At least one resource must be held in a non-shareable mode; If any other process requests this resource, then the process must wait for the resource to be released.

2) Hold and Wait :A process must be simultaneously holding at least one resource and waiting for at least one resource that is currently being held by some other process.

3) No preemption: Once a process is holding a resource, then that resource cannot be taken away from that process until the process voluntarily releases it.

4)Circular Wait : A set of processes {P0,P1,P2, ....PN } must exist such that every P[i] is waiting for P[(i+1)%(N+1)].

How to handle a deadlock ?

1)Generally speaking there are three ways of handling deadlocks:

Deadlock prevention or avoidance - Do not allow the system to get into a deadlocked state.
Deadlock detection and recovery - Abort a process or preempt some resources when deadlocks are detected.
Ignore the problem all together - If deadlocks only occur once a year or so, it may be better to simply let them happen and reboot as necessary than to incur the constant overhead and system performance penalties associated with deadlock prevention or detection.

2) In order to avoid deadlocks, the system must have additional information about all processes. In particular, the system must know what resources a process will or may request in the future.

3)Deadlock detection is fairly straightforward, but deadlock recovery requires either aborting processes or preempting resources, neither of which is an attractive alternative.

4)If deadlocks are neither prevented nor detected, then when a deadlock occurs the system will gradually slow down, as more and more processes become stuck waiting for resources currently held by the deadlock and by other waiting processes. Unfortunately this slowdown can be indistinguishable from a general system slowdown when a real-time process has heavy computing needs.

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Reference

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Friday, October 14, 2016

Chrome Extensions
An extension is a zipped bundle of files- HTML, CSS, JavaScript, images and anything else that is needed and that adds functionality to the Google Chrome browser. Many extensions add UI to the Google Chrome in the form of browser actions or page actions.Each extension can have at most one browser action or page action. A browser action that is most relevant to most pages is chosen. A page action is chosen according to when the extension icon should be active or inactive, depending on the page. Extensions are essentially web pages that can use all the APIs that the browser provides to web page.

Each of the extensions have the following files

A manifest file
One or more HTML files (unless the extension is a theme)
Optional: One or more Javascript files
Optional: Any other files your extension needs- for example, image files

The manifest file, called manifest.json, gives information about the extension such as the most important files and the capabilities that the extension might use.

The most popular Google Chrome Extensions are Honey, Hangouts, Momentum, Office Online, Grammarly, Google Keep and Stay Focused. Each of them improvise the functions provided to us by Chrome.
The Extension Honey helps people find the best deal on any of the online shopping sites. The extension Hangout helps people to keep in touch and communicate.The Extension Google Keep helps people to take notes. The extension Grammarly helps people to get rid of all the typing errors they make while writing an articles. This extensions also fixes all the Grammatical errors and provides better vocabulary and phrasing for the sentences. The extension Stay Focused helps people to avoid getting distracted while researching. Google chrome was extremely powerful in itself but with these extensions added to it, it has become unbeatable.
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Reference

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