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

Explain multidimensional array, Multidimensional array: Multidimensional a...

Multidimensional array: Multidimensional arrays can be defined as "arrays of arrays". For example, a bidimensional array can be imagined as a bidimensional table made of elements,

Signals, How does cpu''s part tming and controls generate and controls sign...

How does cpu''s part tming and controls generate and controls signls in computer?

Recursive and iterative handling of a binary search tree, This section pres...

This section prescribes additional exercise with the recursive and iterative handling of a binary search tree. Adding to the Binary Search Tree Recursively Add implementation

Program segment for quick sort, Illustrates the program segment for Quick s...

Illustrates the program segment for Quick sort. It uses recursion. Program 1: Quick Sort Quicksort(A,m,n) int A[ ],m,n { int i, j, k; if m { i=m; j=n+1; k

What is diffuse illumination, Diffuse Illumination Diffuse illuminatio...

Diffuse Illumination Diffuse illumination means light that comes from all directions not from one particular source. Think about the light of a grey cloudy day as compared to

What is binary search, What is binary search?   Binary search is most ...

What is binary search?   Binary search is most useful when list is sorted. In binary search, element present in middle of the list is determined. If key (the number to search)

Define big omega notation, Define Big Omega notation Big Omega notatio...

Define Big Omega notation Big Omega notation (?) : The lower bound for the function 'f' is given by the big omega notation (?). Considering 'g' to be a function from the non-n

Write a procedure that produces independent stack, Write a procedure (make-...

Write a procedure (make-stack) that produces independent stack objects, using a message-passing style, e.g. (define stack1 (make-stack))  (define stack2 (make-stack)) W

Array implementation of a multiqueue, Program gives the program segment by ...

Program gives the program segment by using arrays for the insertion of an element to a queue into the multiqueue. Program: Program segment for the insertion of any element to t

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