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

What are stored and derived attributes, What are stored and derived attribu...

What are stored and derived attributes?  Stored attributes: The attributes kept in a data base are called stored attributes.  Derived attributes: The attributes that are

What are the advantages of using assertions, Using Assertions When writ...

Using Assertions When writing code, programmer must state pre- and subtle post conditions for public operations, state class invariants and insert unreachable code assertions a

Mathematical-model with a collection of operations, A mathematical-model wi...

A mathematical-model with a collection of operations described on that model is known as??? Abstract Data Type

Program for linear search, Program for Linear Search. Program: Linear S...

Program for Linear Search. Program: Linear Search /*Program for Linear Search*/ /*Header Files*/ #include #include /*Global Variables*/ int search; int

Explain the abstract data type assertions, Explain the Abstract data type a...

Explain the Abstract data type assertions Generally, ADT assertions translate into assertions about the data types which implement ADTs, which helps insure that our ADT impleme

General Tree, How to create an General Tree and how to search general tree?...

How to create an General Tree and how to search general tree?

Analysis of algorithms, A common person's faith is that a computer can do a...

A common person's faith is that a computer can do anything. It is far from truth. In realism computer can carry out only definite predefined instructions. The formal illustration o

Tower of hanoi problem., Write an algorithm for getting solution to the Tow...

Write an algorithm for getting solution to the Tower's of Hanoi problem. Explain the working of your algorithm (with 4 disks) with appropriate diagrams. Ans: void Hanoi(int

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