作者:
Wilmoth, Richard G.NASA
Langley Res Ctr Div Space Syst Aerothermodynam Branch Hampton VA 23665 USA
A method for executing a direct simulation Monte carlo (DSMc) analysis using parallel processing is described. The method is based on using domain decomposition to distribute the work load among multiple processors, a...
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A method for executing a direct simulation Monte carlo (DSMc) analysis using parallel processing is described. The method is based on using domain decomposition to distribute the work load among multiple processors, and the DSMc analysis is performed completely in parallel. Message passing is used to transfer molecules between processors and to provide the synchronization necessary for the correct physical simulation. Benchmark problems are described for testing the method, and results are presented that demonstrate the performance on two commercially available multicomputers. The results show that reasonable parallel speedup and efficiency can be obtained if the problem is sized properly to the number of processors. It is projected that, with a massively parallel system, performance exceeding that of current supercomputers is possible.
Theoretical methods in chemistry frequently involve the tedious solution of complex algebraic equations. Then the solutions, sometimes still quite complex, are usually hand-coded by a programmer into an efficient comp...
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Theoretical methods in chemistry frequently involve the tedious solution of complex algebraic equations. Then the solutions, sometimes still quite complex, are usually hand-coded by a programmer into an efficient computer language. During this procedure it is all too easy to make an error which will go undetected. A better approach would be to introduce the computer at an even earlier stage in the development of the theory by programming it to first solve the set of equations and then compile the solution into an efficient computer language. In this research a program has been written in the cprogramminglanguage which can efficiently compute the quasivacuum expectation value of a product of creation and annihilation operators and scalar arrays. The terms in the resulting expressions are then transformed into a canonical form so that all equivalent terms can be combined. Finally, the equations are compiled into a simple representation which can be rapidly interpreted by a Fortran program. This symbol manipulator has been applied to open-shell coupled cluster theory. Two coupled cluster methods using high-spin open-shell references are presented. In one of these methods, the cluster operator contains the unitary group generators, and products thereof, which generate all single and double excitations with respect to the reference. The other uses a simplified cluster operator which generates equations that must be spin-projected. These methods are compared to other descriptions of electron correlation for the cH2 singlet-triplet splitting and the NH2 potential energy surface.
Reactive systems are interactive programs that react continuously to sequences of activations coming from the external world. Reactive programming leads to a new programming style where one programs in terms of reacti...
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Reactive systems are interactive programs that react continuously to sequences of activations coming from the external world. Reactive programming leads to a new programming style where one programs in terms of reactions to activations and reasons in a logic of instants. This paper describes an extension of the cprogramminglanguagecalled Rc (for 'Reactive c') to program reactive systems. The language Rc is described, then some programming examples are given to illustrate the reactive approach. The main Rc notions come directly from the Esterel synchronous programminglanguage. Finally, the Esterel and Rclanguages are compared.
Recognizing the growing popularity and demand for scientific or numerical libraries in the ccomputer language, and the shortage of systematic methods for the increasingly important non-linear stochastic systems, this...
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Recognizing the growing popularity and demand for scientific or numerical libraries in the ccomputer language, and the shortage of systematic methods for the increasingly important non-linear stochastic systems, this article attempts to present a method to approximate the solution of systems governed by non-linear stochastic differential equations and the corresponding algorithm and computer code in the clanguage. It was found that the clanguage offers promising possibilities for the stochastic systems modeler. It is hoped the use of c for the analysis of these type of problems will be encouraged.
作者:
WEBBER, cLDepartment of Physiology
Loyola University of Chicago Stritch School of Medicine 2160 South First Avenue Maywood IL 60153 U.S.A.
A computer program is described which performs power-spectral analyses on time-domain data. The program is written in the clanguage and incorporates an algorithm for the fast Fourier transform translated from BASIc i...
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A computer program is described which performs power-spectral analyses on time-domain data. The program is written in the clanguage and incorporates an algorithm for the fast Fourier transform translated from BASIc into c. Sequential segments of time-domain data are accessed by the program, transformed to the frequency domain, and ensemble-averaged to generate smoothed spectra. Specific application of the program to the detection of high-frequency oscillations in the phrenic neurogram of the cat is addressed. Thus, 100 successive 512-point fast Fourier transforms were found to accurately reveal the relative strength (power) and frequency position (spectrum) of multiple peaks in this respiratory motor pathway. Because clanguage programs are very transportable, this program should run on machines other than our LSI 11/23, provided a c-compiler is available.
We describe a processing program for radioimmunoassay data which uses a log/logit transformation and maximum likelihood estimation to describe mathematically the standard curve, providing a .chi.2 test of goodness of ...
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We describe a processing program for radioimmunoassay data which uses a log/logit transformation and maximum likelihood estimation to describe mathematically the standard curve, providing a .chi.2 test of goodness of fit for the model. Sample values are returned with 95% fiducial probability intervals or standard errors. The program is written in c, which facilitates transportability and modularity.
Syntax directed editors (SDE) have been built to support popular languages or subsets of those languages. Typically, these im- plementations require large amounts of computing resources. This work describes the design...
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Syntax directed editors (SDE) have been built to support popular languages or subsets of those languages. Typically, these im- plementations require large amounts of computing resources. This work describes the design and implemtnat ion of a SDE which re- quires less than 58 thousand bytes of main memory and supports the full cprogramminglanguage. Several extant SDE models are examined in an effort to define a basic set of SDE facilities. Design principles are combined with machine con- straints to produce a plan for the implementation of these facilities. A sample session with the resulting editor is provided The syntactic irregularities of the cprogramminglanguage are examined. A discussion showing how language irregularities can hamper the implementation of a SDE follows. A grammatical definition of the clanguage is included.
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