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-   -   Can I use Master Theorem if the partitions are not fractions? (http://www.physicsforums.com/showthread.php?t=583297)

 zeion Mar2-12 04:02 PM

Can I use Master Theorem if the partitions are not fractions?

1. The problem statement, all variables and given/known data

If I had a recurrence expression that recurs on partitions of size n - 1 each time, (as opposed some fraction of the original size ie. n/2), how can I apply the Master Theorem? I don't know what the "b" value is?

2. Relevant equations

3. The attempt at a solution

ie. If I had 2 C(n-1) + f(n), what is b?

 Max.Planck Mar4-12 01:40 PM

Re: Can I use Master Theorem if the partitions are not fractions?

You can not use the Master Theorem in this case, just use the recursion tree method. In this case it is easy to see that it will be exponential, since each level has twice the number of nodes of the previous level.

 zeion Mar5-12 08:42 AM

Re: Can I use Master Theorem if the partitions are not fractions?

Quote:
 Quote by Max.Planck (Post 3798094) You can not use the Master Theorem in this case, just use the recursion tree method. In this case it is easy to see that it will be exponential, since each level has twice the number of nodes of the previous level.
I'm not sure what a recursion tree method is..
I see that each recursion will have twice the calls to the function as the last, but they are also on one less element than the last, does that matter?

Actually nevermind, so if I find a closed form expression it will be 2^n, right?

 Max.Planck Mar5-12 08:52 AM

Re: Can I use Master Theorem if the partitions are not fractions?

Quote:
 Quote by zeion (Post 3799418) Actually nevermind, so if I find a closed form expression it will be 2^n, right?
Depends on C(0) and f(n). The recursion tree method should be described in your textbook.

 zeion Mar5-12 09:42 AM

Re: Can I use Master Theorem if the partitions are not fractions?

Oh I see. It says that f(n) is constant. But it doesn't say what C(0) is.

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