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

Algorithm, Algorithm to find sum of square of a number

Algorithm to find sum of square of a number

Explain the arrays in ruby, Explain the Arrays in Ruby Ruby arrays are ...

Explain the Arrays in Ruby Ruby arrays are dynamic arrays which expand automatically whenever a value is stored in a location beyond current end of the array. To the programmer

Explain the theory of computational complexity, Explain the theory of compu...

Explain the theory of computational complexity A  problem's  intractability  remains  the  similar  for  all  principal  models  of   computations    and   all reasonable inpu

Sequential files, In this section, we will discuss about Sequential file or...

In this section, we will discuss about Sequential file organization. Sequential files have data records stored in a particular sequence. A sequentially organized file might be stor

Data structures, I am looking for assignment help on the topic Data Structu...

I am looking for assignment help on the topic Data Structures. It would be great if anyone help me.

Algorithm, Example of worse case of time

Example of worse case of time

Find the optimal control, 1. Use the Weierstrass condition, find the (Stron...

1. Use the Weierstrass condition, find the (Strongly) minimizing curve and the value of J min for the cases where x(1) = 0, x(2) = 3. 2. The system = x 1 + 2u; where

Number of leaf nodes in a complete binary tree, The number of leaf nodes in...

The number of leaf nodes in a complete binary tree of depth d is    2 d

The smallest element of an array''s index, The smallest element of an array...

The smallest element of an array's index is called its Lower bound.

Asymptotic notation, Asymptotic notation Let us describe a few function...

Asymptotic notation Let us describe a few functions in terms of above asymptotic notation. Example: f(n) = 3n 3 + 2n 2 + 4n + 3 = 3n 3 + 2n 2 + O (n), as 4n + 3 is of

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