217,793 research outputs found
Commodity Computing Clusters at Goddard Space Flight Center
The purpose of commodity cluster computing is to utilize large numbers of readily available computing components for parallel computing to obtaining the greatest amount of useful computations for the least cost. The issue of the cost of a computational resource is key to computational science and data processing at GSFC as it is at most other places, the difference being that the need at GSFC far exceeds any expectation of meeting that need. Therefore, Goddard scientists need as much computing resources that are available for the provided funds. This is exemplified in the following brief history of low-cost high-performance computing at GSFC
Finite Computational Structures and Implementations
What is computable with limited resources? How can we verify the correctness
of computations? How to measure computational power with precision? Despite the
immense scientific and engineering progress in computing, we still have only
partial answers to these questions. In order to make these problems more
precise, we describe an abstract algebraic definition of classical computation,
generalizing traditional models to semigroups. The mathematical abstraction
also allows the investigation of different computing paradigms (e.g. cellular
automata, reversible computing) in the same framework. Here we summarize the
main questions and recent results of the research of finite computation.Comment: 12 pages, 3 figures, will be presented at CANDAR'16 and final version
published by IEEE Computer Societ
A quantum computer only needs one universe
The nature of quantum computation is discussed. It is argued that, in terms
of the amount of information manipulated in a given time, quantum and classical
computation are equally efficient. Quantum superposition does not permit
quantum computers to ``perform many computations simultaneously'' except in a
highly qualified and to some extent misleading sense. Quantum computation is
therefore not well described by interpretations of quantum mechanics which
invoke the concept of vast numbers of parallel universes. Rather, entanglement
makes available types of computation process which, while not exponentially
larger than classical ones, are unavailable to classical systems. The essence
of quantum computation is that it uses entanglement to generate and manipulate
a physical representation of the correlations between logical entities, without
the need to completely represent the logical entities themselves.Comment: 13 pages. The paper has undergone major changes, in order to
stengthen the argument and cut extraneous material. Schrodinger's Cat has
been cut. The "one-way computer" model is now included, and the other remarks
tightened. A positive statement on what a QC is, as opposed to what it is
not, is adde
Polynomial-Time Algorithms for Prime Factorization and Discrete Logarithms on a Quantum Computer
A digital computer is generally believed to be an efficient universal
computing device; that is, it is believed able to simulate any physical
computing device with an increase in computation time of at most a polynomial
factor. This may not be true when quantum mechanics is taken into
consideration. This paper considers factoring integers and finding discrete
logarithms, two problems which are generally thought to be hard on a classical
computer and have been used as the basis of several proposed cryptosystems.
Efficient randomized algorithms are given for these two problems on a
hypothetical quantum computer. These algorithms take a number of steps
polynomial in the input size, e.g., the number of digits of the integer to be
factored.Comment: 28 pages, LaTeX. This is an expanded version of a paper that appeared
in the Proceedings of the 35th Annual Symposium on Foundations of Computer
Science, Santa Fe, NM, Nov. 20--22, 1994. Minor revisions made January, 199
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