What is Polyphase Sort, Data Structure & Algorithms

Assignment Help:
One of the best known methods for external sorting on tapes is the polyphase sort.

Principle: The basic strategy of this sort is to distribute ordered initial runs of predetermined size on the available tapes and then to repeatedly merge these runs in multiple phases in which each phase has a predetermined number of merges before a new target tape is selected.

To distribute the initial runs a Fibonacci distribution is adopted. After the distribution of the runs according to Fibonacci distribution, the merging procedure is continued until the tape with the least number of run lists is empty. When this occurs the remaining working tapes are logically rotated such that the newly emptied tape becomes the new target tape and the old target tape then becomes one of the working tapes to be merged. The sort ends when all runs are merged into one.

Let the number of tapes be T and p = T - 1. The Fibonacci distribution for p = 3 is given.

Level

s
Tape
Total number of runs
1
2
3
1
0
0
1
1
2
1
1
1
3
3
1
2
2
5
4
2
3
4
9
5
4
6
7
17
6
7
11
13
31
7
13
20
24
57
8
24
37
44
105
9
44
68
81
193
Algorithm:

1. Let A be the list of N unsorted elements and R be the number of runs.

2. Let T1, T2, T3 and T4 be the tapes on which sorting is done.

3. Split the list A into R=N runs so that each run has only one element.

4. If R is not equal to perfect Fibonacci distribution then add dummy records to bring up perfect Fibonacci distribution.

5. Distribute the records in the remaining tapes according to the Fibonacci distribution.

6. Merge 3 runs, one from each tape and put into next empty tape.

7. Repeat step 6 till a single run is generated.

Related Discussions:- What is Polyphase Sort

Define dynamic programming, Define Dynamic Programming  Dynamic  progra...

Define Dynamic Programming  Dynamic  programming  is  a  method  for  solving  problems  with  overlapping  problems.  Typically, these sub problems arise from a recurrence rel

Circularly linked lists implementation, CIRCULARLY LINKED LISTS IMPLEMENTAT...

CIRCULARLY LINKED LISTS IMPLEMENTATION A linked list wherein the last element points to the first element is called as CIRCULAR linked list. The chains do not specified first o

Procedures, what is far and near procedures in system programming?

what is far and near procedures in system programming?

Algorithmic implementation of multiple stacks, So far, we now have been con...

So far, we now have been concerned only with the representation of single stack. What happens while a data representation is required for several stacks? Let us consider an array X

Relation of time and space complexities of an algorithm, What is complexity...

What is complexity of an algorithm? What is the basic relation between the time and space complexities of an algorithm? Justify your answer by giving an example.

Complexity of an algorithm, compare two functions n and 2n for various valu...

compare two functions n and 2n for various values of n. determine when second becomes larger than first

Memory mapping, lower triangular matrix and upper triangular matrix

lower triangular matrix and upper triangular matrix

Process of channel access, Channel access In first generation systems, ...

Channel access In first generation systems, every cell supports a number of channels. At any given time a channel is allocated to only one user. Second generation systems also

Find the adjacency matrix, Consider the digraph G with three vertices P1,P2...

Consider the digraph G with three vertices P1,P2 and P3 and four directed edges, one each from P1 to P2, P1 to P3, P2 to P3 and P3 to P1. a. Sketch the digraph. b. Find the a

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd