In this note we describe deterministic parallel algorithms for planar point location and for building the Voronoï Diagram of n co-planar points. These algorithms are designed for BSP/CGM-like models of computatio...
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In this note we describe deterministic parallel algorithms for planar point location and for building the Voronoï Diagram of n co-planar points. These algorithms are designed for BSP/CGM-like models of computation, where p processors, with O(n/p) O(1) local memory each, communicate through some arbitrary interconnection network. They are communication-efficient since they require, respectively, O(1) and O(log p) communication steps and O(n log n/p) local computation per step. Both algorithms require O(n/p) = Ω(p) local memory.
Proposes a new parallel algorithm for computing path expressions, named the "parallel cascade semi-join" (PCSJ) algorithm. Moreover, a new scheduling strategy called the "right-deep zigzag tree" is...
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ISBN:
(纸本)0769509967
Proposes a new parallel algorithm for computing path expressions, named the "parallel cascade semi-join" (PCSJ) algorithm. Moreover, a new scheduling strategy called the "right-deep zigzag tree" is designed to further improve the performance of the PCSJ algorithm. The experiments have been implemented in a distributed and parallel NOW (network of workstations) environment. The results show that the PCSJ algorithm outperforms two other parallel algorithms [the parallel forward pointer chasing (PFPC) algorithm and the index-splitting parallel algorithm (IndexSplit)] when computing path expressions with restrictive predicates, and that the right-deep zigzag tree scheduling strategy has a better performance than the right-deep tree scheduling strategy.
We describe sequential and parallel algorithms that approximately solve linear programs with no negative coefficients (aka mixed packing and covering problems). For explicitly given problems, our fastest sequential al...
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We describe sequential and parallel algorithms that approximately solve linear programs with no negative coefficients (aka mixed packing and covering problems). For explicitly given problems, our fastest sequential algorithm returns a solution satisfying all constraints within a 1/spl plusmn//spl epsi/ factor in O(mdlog(m)//spl epsi//sup 2/) time, where m is the number of constraints and d is the maximum number of constraints any variable appears in. Our parallel algorithm runs in time polylogarithmic in the input size times /spl epsi//sup -4/ and uses a total number of operations comparable to the sequential algorithm. The main contribution is that the algorithms solve mixed packing and covering problems (in contrast to pure packing or pure covering problems, which have only "/spl les/" or only "/spl ges/" inequalities, but not both) and run in time independent of the so-called width of the problem.
Software radios are emerging as platforms for multiband multimode radio communication *** the same time, the need for software radios also raises a number of technical challenges,including analog-to-digital conversion...
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Software radios are emerging as platforms for multiband multimode radio communication *** the same time, the need for software radios also raises a number of technical challenges,including analog-to-digital conversion and digital signal processing *** this article,we first discuss the purposes for digital processing in software radio, and we then identify the most important requirements for DSP ***,we discuss the signal processing algorithms in software radio and present a software radio model and trial-platform based on multi-DSP parallel algorithms.
This paper constructs a class of parallel Adams algorithms for the systems of delay differential equations. The results on convergence and stability are given. The theoretical analysis and numerical test shows that th...
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This paper constructs a class of parallel Adams algorithms for the systems of delay differential equations. The results on convergence and stability are given. The theoretical analysis and numerical test shows that this algorithm is effect and comparable.
Given N matrices A/sub 1/, A/sub 2/,..., A/sub N/ of size N/spl times/N, the matrix chain product problem is to compute A/sub 1//spl times/A/sub 2//spl times//spl middot//spl middot//spl middot/A/sub N/. Given an N/sp...
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ISBN:
(纸本)0769509908
Given N matrices A/sub 1/, A/sub 2/,..., A/sub N/ of size N/spl times/N, the matrix chain product problem is to compute A/sub 1//spl times/A/sub 2//spl times//spl middot//spl middot//spl middot/A/sub N/. Given an N/spl times/N matrix A, the matrix powers problem is to calculate the first N powers of A, i.e., A, A/sup 2/A/sup 3/,..., A/sup N/. We consider distributed memory systems (DMS) with p processors that can support one-to-one communications in O(T(p)) time. Assume that the time complexity of the best known sequential algorithm for matrix multiplication is O(N/sup /spl alpha//), where /spl alpha/<2.3755. Let p be arbitrarily chosen in the range 1/spl les/p/spl les/N/sup /spl alpha/+1//log N. We show that the two problems can be solved on a p-processor DMS in T/sub chain/(N,p)=O(N/sup /spl alpha/+1//p+T(p)(N/sup 2(1+1//spl alpha/)//p/sup 2// /sup /spl alpha//(log p/N)/sup 1-2//spl alpha//+log(p log N/N/sup /spl alpha//) log N)) and T/sub power/(N,p)=0(N/sup /spl alpha/+1//p+T(p)(N/sup 2(1+1//spl alpha/)//p/sup 2// /sup /spl alpha//(log p/log N)/sup 1-2//spl alpha//+(log N)/sup 2/)) times, respectively. We also give instantiation of the above results in distributed memory parallel computers and DMS with hypercubic networks, and show that our parallel algorithms are either fully scalable or highly scalable.
In this paper we present a general approach for reducing switching activity on the algorithmic level. We concentrate on iterative algorithms that are suitable for an implementation on parallel processor arrays. The re...
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ISBN:
(纸本)0780366859
In this paper we present a general approach for reducing switching activity on the algorithmic level. We concentrate on iterative algorithms that are suitable for an implementation on parallel processor arrays. The reduction is substantially reached by avoiding operations that hardly contribute to the convergence of the implemented algorithm. Our general approach is exemplified on the implementation of a specific algorithm, i.e. the eigenvalue decomposition (EVD) of a real symmetric matrix.
We present parallel algorithms to find cut vertices, bridges, and Hamiltonian Path in bounded interval tolerance graphs. For a graph with n vertices, the algorithms require O(log n) time and use O(n) processors to run...
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ISBN:
(纸本)0769511538
We present parallel algorithms to find cut vertices, bridges, and Hamiltonian Path in bounded interval tolerance graphs. For a graph with n vertices, the algorithms require O(log n) time and use O(n) processors to run on Concurrent Read Exclusive Write parallel RAM (CREW PRAM) model of computation. Our approach transforms the original graph problem to a problem in computational geometry. The total work done by the parallel algorithms is comparable to the work done by the best known sequential algorithms for the more restricted class of graphs, namely, interval graphs and permutation graphs. In this sense our algorithms have optimal complexity.
This paper presents BSR-parallel algorithms for three geometrical problems: point location, convex hull and smallest enclosing rectangle. These problems are solved in constant time using the BSR model introduced by Ak...
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ISBN:
(纸本)0769509878
This paper presents BSR-parallel algorithms for three geometrical problems: point location, convex hull and smallest enclosing rectangle. These problems are solved in constant time using the BSR model introduced by Akl and Guenther in 1989. The first algorithm uses O(N) processors (N is the number of edges of the polygon R). The second uses O(N'/sup 2/) processors (N' is the number of points) and the third one uses O(N'/sup 2/) processors (it need the convex hull) to solve the smallest enclosing rectangle problem. These new results suggest that many other geometrical problems can be solved in constant time using the BSR model.
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