AQA A2 Computing - COMP3 11/06/13

KING2011BOB

What I can remember

1a) Which constructs are valid in this language

I got No,Yes,Yes,No

1b) What is wrong with the BNF

1c) Why is a recursive structure used for this?

2) (Tree traversal generally I think)

a) The root node ( +)
b) The leaf notes (Not too sure)

c) Run through the algorithm,bow down to anyone who could do that

d) Postfix traversal
e) What does the output give you? (Not too sure whether im right)

3a) D
A
C

3b) 40

3c) -7.75 in binary = 1.1001000 x 2^ (0011) (Something like that)

4) Types of error

a) absolute error was the (Integer - the rounded value)

b) Relative error = Integer / absolute error as a % (O.3%?)

c) How could you improve the precision,store a larger mantissa :wink:

Intractable problem-has a solution,but takes polynomial time to solve as the input n increases.

Thats as far as my memory stretches sadly folks

Reply 301

slash2k0

Original post by KING2011BOB

Still though I don't believe the paper was started in the right manner! Only dropping 2 marks there though so oh well

I finished this paper with like 1 hour and a half to go what is with that? Everyone did have a final question of Q9?

Just seemed so short,although a lot of marks were longer ones towards the end really

Our whole class got let out an hour early because everyone had finished!

I definitely messed up the recursive tree algorithm though, for some reason I just put that it returned the numbers in the leaf nodes, I didn't see how it could have returned the * and +? :/ Hopefully I'll still save some marks as I think I traced the first part ok though...

Reply 302

KING2011BOB

Original post by slash2k0

Our whole class got let out an hour early because everyone had finished!

I definitely messed up the recursive tree algorithm though, for some reason I just put that it returned the numbers in the leaf nodes, I didn't see how it could have returned the * and +? :/ Hopefully I'll still save some marks as I think I traced the first part ok though...

Same man,darn thats exactly what it did! I wondered why I didn't get any operands!

There were only 9 questions,no class inheritance OOP stuff?

Reply 303

JASApplications

Did you leave the relative error as absolute error/actual value or did you turn it into a percentage?

I left it as the absolute error/actual value.

Reply 304

ks2924

Original post by KING2011BOB

4) Types of error

a) absolute error was the (Integer - the rounded value)

b) Relative error = Integer / absolute error as a % (O.3%?)

Thats as far as my memory stretches sadly folks

For the absolute and relative error I had no idea so I put the Integer - rounded value twice, 1's better than none!

Reply 305

TheGreat1

2

Original post by SerialVelocity

I got 40 for the denary. :P To convert -7.75, I did this:

Convert -7.75 to fixed point:

7.75 = 0111.11
-7.75 = 1000.01

Move the radix point 3 to the right (so that there is no trailing 0's):

1.00001

That is the mantissa, the exponent is 3.

is the exponent not -3 ?
because you had to move 3 places to the left

Reply 306

fizzbizz

4

Original post by JASApplications

Did you leave the relative error as absolute error/actual value or did you turn it into a percentage?

I left it as the absolute error/actual value.

Same- was also annoyed they didn't say to how many significant figures!

Posted from TSR Mobile

Reply 307

fizzbizz

4

Original post by TheGreat1

is the exponent not -3 ?
because you had to move 3 places to the left

The represented value needed to have the decimal place moved three places to the right to get back to the actual value

Posted from TSR Mobile

Reply 308

absism

Original post by SerialVelocity

I got 40 for the denary. :P To convert -7.75, I did this:

Convert -7.75 to fixed point:

7.75 = 0111.11
-7.75 = 1000.01

Move the radix point 3 to the right (so that there is no trailing 0's):

1.00001

That is the mantissa, the exponent is 3.

I see...well, i'll get atleast 1 mark out the 3 lol

Reply 309

KING2011BOB

Original post by fizzbizz

The represented value needed to have the decimal place moved three places to the right to get back to the actual value

Posted from TSR Mobile

Im pretty sure it was 3 places to the left pal as you got like 1011.10 then you move that so its in the most precise form i.e 1011100(this is an example) and you move it left so need to x 2^3 to get back to the - 7.75

(edited 10 years ago)

Reply 310

KING2011BOB

There were only 9 questions yeah,im quite worried about that?

Reply 311

luketg8

It wasn't too bad of a paper, but surely the boundaries will be lower than last year?! What do people think they will be? :s-smilie:

Reply 312

Mystogan.

Ended up spending 20 minutes on that algorithm question at the end and still managed to mess it up :frown:

Also wasn't sure whether to multiply my answer for the relative error question by 100 or not (percentage)

Reply 313

absism

Original post by KING2011BOB

What I can remember

1a) Which constructs are valid in this language

I got No,Yes,Yes,No

1b) What is wrong with the BNF

1c) Why is a recursive structure used for this?

2) (Tree traversal generally I think)

a) The root node ( +)
b) The leaf notes (Not too sure)

c) Run through the algorithm,bow down to anyone who could do that

d) Postfix traversal
e) What does the output give you? (Not too sure whether im right)

3a) D
A
C

3b) 40

3c) -7.75 in binary = 1.1001000 x 2^ (0011) (Something like that)

4) Types of error

a) absolute error was the (Integer - the rounded value)

b) Relative error = Integer / absolute error as a % (O.3%?)

c) How could you improve the precision,store a larger mantissa :wink:

Intractable problem-has a solution,but takes polynomial time to solve as the input n increases.

Thats as far as my memory stretches sadly folks

Adding on what I remember, which is just the last question really. It was the easiest one out of all tbh.

9. a) EDR - Customer-Order, Order-OrderLine, Order-Furniture; all one-many, but i think i put customer-order as many-many since many customers can make many orders...probably wrong tbh.

b) Create table Furniture(
FurnitureID Int (not null)
FurnitureName varchar(20)
SupplierName varchar(20)
Price Currency
(one other field i can't remember name of)
Primary Key (FurnitureID)
)

c) SQL:
SELECT CustomerName, Telephone Number
FROM Customer, CustomerOrder, CustomerOrderLine
WHERE FurnitureID = (whatever the ID was)
AND CustomerOrder.CustomerID = Customer.CustomerID
AND CustomerOrderLine.OrderID = CustomerOrder.OrderID
ORDER BY CustomerName ASC

d) Alter Table

Everyone already knows about the networks long-marker one I think. There were some IP addresses you had to write down at the start of that question. Asked you the definition of server operating system and something about why wi-fi is used rather than Bluetooth.

The state transition one was pretty straight-forward as well.

Reply 314

absism

Original post by Mystogan.

Ended up spending 20 minutes on that algorithm question at the end and still managed to mess it up :frown:

Also wasn't sure whether to multiply my answer for the relative error question by 100 or not (percentage)

No need to multiply. Neither absolute, nor relative error are %'s. Both are just decimal numbers. Absolute was 0.025 i think and relative 0.025/6.9.

Reply 315

moogoomonkey

1

Original post by KING2011BOB

Im pretty sure it was 3 places to the left pal as you got like 1011.10 then you move that so its in the most precise form i.e 1011100(this is an example) and you move it left so need to x 2^3 to get back to the - 7.75

As in to get BACK to the actual value you need to move 3 places to the right

Reply 316

fizzbizz

4

Original post by KING2011BOB

Im pretty sure it was 3 places to the left pal as you got like 1011.10 then you move that so its in the most precise form i.e 1011100(this is an example) and you move it left so need to x 2^3 to get back to the - 7.75

Well yes that's exactly what I'm saying.. The guy who I was replying to said the exponent was -3..

Reply 317

fizzbizz

4

A lot of stuff I was expecting didn't show up in this exam

Operating systems, mealy/moore machines, writing class definitions, regular expressions, adjacency matrices/lists, programming paradigms, hashing, insertion sort

Reply 318

luketg8

Original post by fizzbizz

A lot of stuff I was expecting didn't show up in this exam

Operating systems, mealy/moore machines, writing class definitions, regular expressions, adjacency matrices/lists, programming paradigms, hashing, insertion sort

tell me about it :angry:

Reply 319

alphadawg

3

I'm looking forward to reading the examiner's report.

AQA A2 Computing - COMP3 11/06/13

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