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

Addressing modes, Compare zero-address, one-address, two-address, and three...

Compare zero-address, one-address, two-address, and three-address machines by writing programs to compute: Y = (A – B X C) / (D + E X F) for each of the four machines. The inst

State about the pseudocode, State the Introduction to pseudocode No spe...

State the Introduction to pseudocode No specific programming language is referred to; development of algorithms by using pseudocode uses generic descriptions of branching, loop

Representing sparse matrix in memory using array, Q. What do you understand...

Q. What do you understand by the term sparse matrix? How sparse matrix is stored in the memory of a computer? Write down the function to find out the transpose of a sparse matrix u

Define the term - array, Define the term - Array A fixed length, ord...

Define the term - Array A fixed length, ordered collection of values of same type stored in contiguous memory locations; collection may be ordered in several dimensions.

Polynomials, Polynomials like  5x 4    +  2x 3    +  7x 2     +  10x  -  8...

Polynomials like  5x 4    +  2x 3    +  7x 2     +  10x  -  8  can  be  represented by using arrays. Arithmetic operations such as addition & multiplication of polynomials are com

Explain arrays, Arrays :- To execute a stack we need a variable called top,...

Arrays :- To execute a stack we need a variable called top, that holds the index of the top element of stack and an array to hold the part of the stack.

Explain in detail about the ruby arrays, Explain in detail about the Ruby a...

Explain in detail about the Ruby arrays Ruby arrays have many interesting and powerful methods. Besides indexing operations which go well beyond those discussed above, arrays h

State cmy model, CMY Model  The cyan, magenta, yellow (CMY) colour mode...

CMY Model  The cyan, magenta, yellow (CMY) colour model is a subtractive model based on the colour absorption properties of paints and inks. As such it has become the standard

What is bubble sort, What is bubble sort? Bubble Sort: The basic ide...

What is bubble sort? Bubble Sort: The basic idea in bubble sort is to scan the array to be sorted sequentially various times. Every pass puts the largest element in its corr

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