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KNOWLEDGE ENGINEERING: PRINCIPLES AND TECHNIQUES<br />

Proceedings of the International Conference on Knowledge Engineering,<br />

Principles and Techniques, KEPT2009<br />

Cluj-Napoca (Romania), July 2–4, 2009, pp. 227–230<br />

EFFICIENT RECURSIVE PARALLEL PROGRAMS FOR<br />

POLYNOMIAL INTERPOLATION<br />

VIRGINIA NICULESCU (1)<br />

Abstract. PowerList and PowerArray theories are well suited to express recursive,<br />

data-parallel algorithms. Their abstractness is very high and assures simple<br />

and correct design of parallel programs. This high level of abstraction could be<br />

reconciled with performance by introducing data-distributions into these theories.<br />

We present in this paper the derivation of a correct recursive program for<br />

Lagrange interpolation. The associated costs are analysed and based on this an<br />

improvement of the program is presented.<br />

1. Introduction<br />

In this paper we extend the work presented in [5] by using data distributions<br />

for parallel programs defined using PowerArray structures. Also, by using these<br />

distributions we define also a possibility to define set-distributions.<br />

2. Distributions<br />

The ideal method to implement parallel programs described with P owerLists is<br />

to consider that any application of the operators tie or zip as deconstructors, leads<br />

to two new processes running in parallel, or, at least, to assume that for each element<br />

of the list there is a corresponding process. A more practical approach is to consider<br />

a bounded number of processes np. In this case we have to transform the input list,<br />

such that no more than np processes are created. This transformation of the input<br />

list corresponds to a data distribution.<br />

2.1. PowerList Distributions. Distributions were introduced in [5], where the advantages<br />

are presented of using them, too. Functions defined on PowerLists can be<br />

easily transformed to accept distributions. By formally introducing the distributions<br />

on PowerLists, we can evaluate costs, depending on the number of available processors<br />

- as a parameter.<br />

2000 Mathematics Subject Classification. 68Q85, 65Y20.<br />

Key words and phrases. parallel computation, abstraction, design, distribution, data-structures.<br />

227<br />

c○2009 Babe¸s-Bolyai University, Cluj-Napoca

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