Computational Methods

Question 1

Computable

Answer 1

Computable if we can come up with an algorithm which will solve the problem in a finite number of steps

Question 2

intractable problem

Answer 2

a problem that cannot be completely solved e.g. travelling salesperson problem

Question 3

problem decomposition

Answer 3

The process of taking a big problem and breaking it down into smaller problems until you have fully explored each of the problems. (Each smaller problem = one module of code)

Question 4

Abstraction

Answer 4

The process of deciding which details are needed to solve the problem and removing the unnecessary details to help solve the problem more easily.

Question 5

Divide and Conquer

Answer 5

reduces the size of the problem over successive iterations: look at a set of rules, discard data then repeat with left over information.

Question 6

Performance modelling

Answer 6

the process of carrying out mathematical approximations of how well models perform.

Question 7

benefits of performance modelling:

Answer 7

• tests a program before its made, helps prevent on air failure
• saves money (the complex calculations are not actually carried out
• helps find unexpected errors
• system is more easily analysed

Question 8

Pipelining

Answer 8

The process of taking a task and splitting it into smaller tasks then overlapping the processing to improve the overall performance

Question 9

Advantages of pipelining

Answer 9

• improves performance, increases throughput

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Question 10

disadvantages of piplining

Answer 10

• doesn’t always improve performance
• physical design and code is more complex
• if a pipeline has to be flushed it wastes time
• not all instructions can take advantage of pipelines

Question 11

drawbacks of performance modelling

Answer 11

• can be expensive to build a model

- sometimes it is difficult to interpret the results

Question 12

advantages of abstraction

Answer 12

• simplifies the problem (it can process faster/ has better memory requirements)

Question 13

disadvantages of abstraction

Answer 13

• may remove too much detail (i.e. the program may be too simple and not reach the users needs.

Question 14

disadvantages of divide and conquer

Answer 14

• may not be complex enough/ may not be able to be split
• can result in full stacks
• may end up duplicating subproblems

Question 15

advantages of modules

Answer 15

• Work can divided between a team, saves time as work takes place in parallel
• each team must only know what values to go into their subroutine and their expected functionality
• breaks problem down, easier to understand/test/debug/read
• Modules can be given to teams with specific expertise
• each subroutine can be tested individually before its combined to the main program
• code can be reused

Question 16

disadvantages of modules

Answer 16

• it can be hard to join all the modules together
• extra memory space and time for execution required
• testing and debugging can be more time consuming

Question 17

Visualisation

Answer 17

The ability to picture a problem and its solution in a visual way to make it easier to understand

Question 18

visualisation advantages

Answer 18

• helps understanding

Question 19

visualisation disadvantages

Answer 19

• time consuming

Question 20

backtracking

Answer 20

the process of incrementally building up towards a solution, abandoning partial success then going back and trying again a different way.

Question 21

concurrent programming

Answer 21

where one computation occurs simultaneously with another and doesn’t wait for the other one before advancing.

Question 22

advantages of backtracking

Answer 22

• sometimes it is the best option to solve a problem

- simple to implement

Question 23

disadvantages of backtracking

Answer 23

• not efficient for solving a strategic problem
• runtime is slow
• need alot of memory space
• to solve larger problems other algorithms may be required

Question 24

Heuristic

Answer 24

Making use of experience to find an acceptable solution (not always the optimal solution).
e.g. rules of thumb, educated guessed, common sense. Often derived from a previous experience with a similar problem

Question 25

advantages of concurrent programming

Answer 25

• increased program throughput

- processor time not wasted

Question 26

disadvantages of concurrent programming

Answer 26

• potential slow down if many users request a similar action

- some problems are not paralisable

Question 27

Data Mining advantages

Answer 27

• can help businesses (target ads, look at trends, predict demand etc)
• analyse records to build patterns and stop criminal activities

Question 28

Data mining disadvantages

Answer 28

• privacy issues
• security issues
• misuse of information
• incorrect analysis can lead to bad effects