d2jsp
Log InRegister
d2jsp Forums > Off-Topic > General Chat > Homework Help > Iso Help With Recurrence Problem
12Next
Add Reply New Topic New Poll
Member
Posts: 19,514
Joined: Feb 21 2011
Gold: 3,877.57
Oct 5 2013 05:16pm
A(b) = A(b/2) + A(b/4) for b is an even power of 4 > 0
A(1) = 1.
Paying well for explanation.

This post was edited by MsRailgun on Oct 5 2013 05:38pm
Member
Posts: 30,822
Joined: Dec 29 2007
Gold: 5,402.07
Oct 5 2013 05:24pm
just dont forget about dre
Member
Posts: 19,387
Joined: Jan 16 2008
Gold: Locked
Warn: 30%
Oct 5 2013 05:43pm
3.
Member
Posts: 10,812
Joined: Oct 15 2009
Gold: Locked
Warn: 20%
Oct 5 2013 06:30pm
Quote (MsRailgun @ Oct 5 2013 04:16pm)
A(b) = A(b/2) + A(b/4) for b is an even power of 4 > 0
does not compute, please rephrase.

Member
Posts: 19,514
Joined: Feb 21 2011
Gold: 3,877.57
Oct 5 2013 06:52pm
Quote (Azrad @ Oct 5 2013 07:30pm)
does not compute, please rephrase.


:huh:
Member
Posts: 28,331
Joined: Jun 9 2007
Gold: 11,700.00
Oct 5 2013 07:16pm
Quote (MsRailgun @ 6 Oct 2013 00:52)
:huh:


not a good form of rephrasing the problem
without any further information the op does not allow to provide you with a solution
so please spell out the complete question you have been asked to answer
Member
Posts: 15,293
Joined: Jul 9 2012
Gold: 3,000.00
Oct 5 2013 07:48pm
if you wrote the question wrong or mistook parts of the question for something else, and there's no solution is probably why you're asking for help lol

recheck +1

This post was edited by Sefira on Oct 5 2013 07:48pm
Member
Posts: 13,578
Joined: Jul 27 2010
Gold: 2,285.00
Oct 5 2013 11:44pm
Quote (MsRailgun @ Oct 5 2013 07:16pm)
A(b) = A(b/2) + A(b/4) for b is an even power of 4 > 0
A(1) = 1.
Paying well for explanation.

It's not 'recurrence'. The phrase you want is mathematical induction.

To prove something by mathematical induction, you need to first prove the "base case", meaning the very lowest number that fits the definition given in your problem. What I can't understand, though, is what you mean by "b is an even power of 4 > 0".

The second step is to first assume that you have some arbitrary (and valid) value for b that the equation works for. Assume A(k) == A(k/2) + A(k/4). Now from there, prove that the equation is also true for A("k+1"). I said k+1, but in reality that depends on how you're defining your allowed b values. If it's even powers of 4, then assume A(k) and prove A(16k) is also true. It's whatever the next highest allowed value for b is. For even powers of 4, that means you would have to multiple by 4^2 to get to the next even power of 4.
Member
Posts: 7
Joined: Oct 5 2013
Gold: 0.00
Oct 6 2013 12:20am
Quote (bentherdonethat @ Oct 6 2013 12:44am)
It's not 'recurrence'. The phrase you want is mathematical induction.

To prove something by mathematical induction, you need to first prove the "base case", meaning the very lowest number that fits the definition given in your problem. What I can't understand, though, is what you mean by "b is an even power of 4 > 0".

The second step is to first assume that you have some arbitrary (and valid) value for b that the equation works for. Assume A(k) == A(k/2) + A(k/4). Now from there, prove that the equation is also true for A("k+1"). I said k+1, but in reality that depends on how you're defining your allowed b values. If it's even powers of 4, then assume A(k) and prove A(16k) is also true. It's whatever the next highest allowed value for b is. For even powers of 4, that means you would have to multiple by 4^2 to get to the next even power of 4.


I think the OP is describing a recurrence relation though...

and I don't think it's a proof; the problem is to find the A function probably
Member
Posts: 10,812
Joined: Oct 15 2009
Gold: Locked
Warn: 20%
Oct 6 2013 12:39am
Quote (Generator @ Oct 5 2013 11:20pm)
I think the OP is describing a recurrence relation though...

and I don't think it's a proof; the problem is to find the A function probably

this is what i think as well^^^
but I can't quite understand this part:
Quote
for b is an even power of 4 > 0



Go Back To Homework Help Topic List
12Next
Add Reply New Topic New Poll