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

Example of pre order traversal, Example of pre order traversal: Reading of...

Example of pre order traversal: Reading of a book, since we do not read next chapter unless we complete all sections of previous chapter & all its sections. Figure  : Rea

Write the algorithm to find input and output value, This algorithm inputs 5...

This algorithm inputs 5 values and outputs how many input numbers were positive and how many were negative. Data to be used: N = 1, -5, 2, -8, -7

Flow chart, What is tha flow chart of algorithm

What is tha flow chart of algorithm

Computer arhitecture, The controversy of RISC versus CISC never ends. Suppo...

The controversy of RISC versus CISC never ends. Suppose that you represent an advocate for the RISC approach; write at least a one-page critic of the CISC approach showing its disa

Draw trace table and determine output of number, Draw trace table and deter...

Draw trace table and determine output from the following flowchart using following data: Number = 45, -2, 20.5

Illustrate hls colour model, HLS Colour Model  This model has the doub...

HLS Colour Model  This model has the double-cone representation shown in Figure 3.40. The three colour parameters in this model are called hue (H), lightness (L), and Saturati

Link list, algorithm for multiplication of two sparse matrices using link l...

algorithm for multiplication of two sparse matrices using link list

Algorithm to insert a node in between any two nodes, Q. Write down an algor...

Q. Write down an algorithm to insert a node in between any two nodes in a linked list         Ans. Insertion of a the node after the given element of the listis as follows

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