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 order of growth, Define order of growth The  efficiency  analysi...

Define order of growth The  efficiency  analysis  framework  concentrates   on  the  order  of  growth  of  an  algorithm's   basic operation count as the principal indicator o

Sorting, how to do a merge sorting

how to do a merge sorting

Dynamic programming., Count Scorecards(30 points) In a tournament, N playe...

Count Scorecards(30 points) In a tournament, N players play against each other exactly once. Each game results in either of the player winning. There are no ties. You have given a

Notes, Ask question #Minimum 10000 words accepted#

Ask question #Minimum 10000 words accepted#

Simulation of queues, Simulation is the process of making an abstract model...

Simulation is the process of making an abstract model of a real world situation in order to be aware of the effect of modifications and alterations and the effect of introducing nu

Logic circuits, the voltage wave forms are applied at the inputs of an EX-O...

the voltage wave forms are applied at the inputs of an EX-OR gate. determine the output wave form

Selection sort, how to reduce the number of passes in selection sort

how to reduce the number of passes in selection sort

Evaluation of arithmetic expressions, Stacks are often used in evaluation o...

Stacks are often used in evaluation of arithmetic expressions. An arithmetic expression contains operands & operators. Polish notations are evaluated through stacks. Conversions of

Structural Induction, Let a be a well-formed formula. Let c be the number o...

Let a be a well-formed formula. Let c be the number of binary logical operators in a. (Recall that ?, ?, ?, and ? are the binary logical operators). Let s be the number of proposit

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