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

Infix expression into the postfix expression, Q. Write down an algorithm to...

Q. Write down an algorithm to convert an infix expression into the postfix expression.     Ans. Algo rithm to convert infix expression to post fix expression is given as

Heights of 500 students `Algorithms`, Write an algorithm, using a flowchart...

Write an algorithm, using a flowchart, which inputs the heights of all 500 students and outputs the height of the tallest person and the shortest p erson in the school.

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

Illumination of wire frame, Illumination of wire frame The colour or sh...

Illumination of wire frame The colour or shade that a surface appears to the human eye depends primarily on three  factors : Colour and strength of incoming illumination

Asymptotic analysis, Asymptotic Analysis Asymptotic analysis is dependi...

Asymptotic Analysis Asymptotic analysis is depending on the idea that as the problem size grows, the complexity can be defined as a simple proportionality to some known functio

Spanning trees, Spanning Trees: A spanning tree of a graph, G, refer to a ...

Spanning Trees: A spanning tree of a graph, G, refer to a set of |V|-1 edges which connect all vertices of the graph. There are different representations of a graph. They are f

Numerical - algorithm, Q. What is the smallest value of n such that an algo...

Q. What is the smallest value of n such that an algorithm whose running time is 100n2 runs faster than an algorithm whose running time is 2n on the same machine.    A n

What is quick sort, What is quick sort? Quick sort is a sorting algorit...

What is quick sort? Quick sort is a sorting algorithm that uses the idea if split and conquer. This algorithm chooses an element called as pivot element; search its position in

A full binary tree with n leaves, A full binary tree with n leaves have:- ...

A full binary tree with n leaves have:- 2n -1 nodes.

Present the algorithm of binary search. , B i n a ry Search Alg...

B i n a ry Search Algorithm is given as follows 1. if (low > high) 2.     return (-1) 3. mid = (low +high)/2; 4. if ( X = = a [mid]) 5.      return (mid); 6.

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