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

Describe data structure?, Typical programming languages such as Pascal, C o...

Typical programming languages such as Pascal, C or Java give primitive data kinds such as integers, boolean, reals values and strings. They give these to be organised into arrays,

Define the term counting - pseudocode, Define the term counting - Pseudocod...

Define the term counting - Pseudocode Counting in 1s is quite simple; use of statement count = count + 1 would enable counting to be done (for example in controlling a repeat

Road transport booking system, what algorithms can i use for the above titl...

what algorithms can i use for the above title in my project desing and implmentation of road transport booking system

Define big oh notation, Big oh notation (O) : The upper bound for the funct...

Big oh notation (O) : The upper bound for the function 'f' is given by the big oh notation (O). Considering 'g' to be a function from the non-negative integers to the positive real

Frequency counts for all statements, Evaluate the frequency counts for all ...

Evaluate the frequency counts for all statements in the following given program segment. for (i=1; i ≤ n; i ++) for (j = 1; j ≤ i; j++) for (k =1; k ≤ j; k++) y ++;

Algorithm of decorated graph, As we talked in class, a program with two int...

As we talked in class, a program with two integer variables is universal. Now, we consider a special form of four variableprograms. Let G = (V; E) be a directed graph, where V is a

Grounded header link list and a circular header link list, What is the diff...

What is the difference between a grounded header link list and a circular header link list? A header linked list is a linked list which always having a special node, known as t

Array implementation of a circular queue, A circular queue can be implement...

A circular queue can be implemented through arrays or linked lists. Program 6 gives the array implementation of any circular queue. Program 6: Array implementation of any Circu

Implement an algorithm to simulate car re-organizing, Design  and implement...

Design  and implement  an algorithm  to simulate car  re-organizing of the train at the railway switching junction. You can only use stacks as the data structure to represent the t

Explain expert system, 1. What is an expert system and where are they need...

1. What is an expert system and where are they needed? 2. What are the major issues involved in building an expert system?

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