Lloyd D. Fosdick

Data Flow Analysis in Software Reliability

The ways that the methods of data flow analysis can be applied to improve software reliability are described. There is also a review of the basic terminology from graph theory and from data flow analysis in global program optimization. The notation of regular expressions is used to describe actions on data for sets of paths. These expressions provide the basis of a classification scheme for data flow which represents patterns of data flow along paths within subprograms and along paths which cross subprogram boundaries. Fast algorithms, originally introduced for global optimization, are described and it is shown how they can be used to implement the classification scheme. It is then shown how these same algorithms can also be used to detect the presence of data flow anomalies which are symptomatic of programming errors. Finally, some characteristics of and experience with DAVE, a data flow analysis system embodying some of these ideas, are described.

Dave—a validation error detection and documentation system for fortran programs†

This paper describes DAVE, a system for analysing Fortran programs. DAVE is capable of detecting the symptoms of a wide variety of errors In programs, as well as assuring the absence of these errors. In addition, DAVE exposes and documents subtle data relations and flows within programs. The central analytic procedure used is a depth first search. DAVE itself is written in Fortran. Its implementation at the University of Colorado and some early experience are described.

An introduction to high-performance scientific computing

An overview of scientific computing: introduction, large-scale scientific problems, the scientific computing environment, workstations, supercomputers, further reading. Part 1 Background: a review of selected topics from numerical analysis - notation, error, floating-point numbers, Taylors series, linear algebra, differential equations, fourier series IEEE arithmetic short reference - single precision, double precision, rounding, infinity, NaN, and zero, of things not said, further reading UNIX, vi, and ftp - a quick review - UNIX short reference, vi short reference, ftp short reference elements of UNIX make - introduction, an example of using make, some advantages of make, the makefile, further examples, dynamic macros, user-defined macros, additional features, other examples, a makefile for C, creating your own makefile, futher information, a makefile for fortran modules, a makefile for C modules elements of fortran - introduction, overview, definitions and basic rules, description of statements, reading and writing, examples. Part 2 Tools: elements of matlab - what is MATLAB?, getting started, some examples, short outline of the language, built-in functions, MATLAB scripts and user-defined functions, input/output, graphics, thats it! elements of IDL - getting started, exploring the basic concepts, plotting, programming in IDL, input/output, using IDL efficiently, summary elements of AVS - basic concepts, AVS graphical programming - the Network editor, the geometry viewer, AVS applications, further reading. Part 3 Scientific visualization: scientific visualization - definitions and goals of scientific visualization, history of scientific visualization, example of scientific visualization, concepts of scientific visualization, visual cues, characterization of scientific data, visualization techniques, annotations, interactivity, interpretation goals to pursue with visualization, quantitative versus qualitative data interpretation. Part 4 Architectures: computer performance - introduction and background, computer performance, benchmarks, the effect of optimizing compilers, other architectural factors, vector and parallel computers, summary. (Part contents).

Some experience with DAVE: a Fortran program analyzer

This paper describes DAVE, an automatic program testing aid which performs a static analysis of Fortran programs. DAVE analyzes the data flows both within and across subprogram boundaries of Fortran programs, and is able to detect occurrences of uninitialized and dead variables in such programs. The paper shows how this capability facilitates the detection of a wide variety of errors, many of which are often quite subtle. The central analytic mechanism in DAVE is a depth-first search procedure which enables DAVE to execute efficiently. Some experiences with DAVE are described and evaluated and some future work is projected.

The production of better mathematical software

Some observations are made on steps to be taken toward the creation of better mathematical software. These steps suggest the need for a coordinated effort and the creation of a center to focus activities in this area.

Program testing techniques using simulated execution

Simulation is proving to be a valuable technique in testing computer programs. By simulating different aspects of a programs execution and structure it is possible to detect errors and sometimes demonstrate the absence of certain errors in the program. This presentation will explore three popular testing methodologies which employ simulation techniques. Each methodology is based upon a different type of simulation of the program. The differences in error detection capability resulting from these different choices of simulated execution will be examined. Finally a method for using the best characteristics of each technique in a general validation system will be presented.

An optimizing precompiler for finite-difference computations on a vector computer

Abstract This paper is concerned with techniques for translating array expressions, as found in FORTRAN 8X, into very efficient vector expressions on a machine in which long vectors are needed for high performance. It describes the application of these techniques in a precompiler for the CYBER 205 which requires a vector length of 1000 to achieve 90% of the asymptotic speed. The precompiler does not vectorize FORTRAN 77 DO loops, instead it vectorizes and optimizes programs written in the explicit array syntax of the proposed FORTRAN standard (FORTRAN 8X). The optimization of the vector code is intended to be most effective for algorithms commonly used in finite-difference approximations of partial differential equations. Finite-difference schemes frequently evaluate the same expression over the interior of a multidimensional rectangular array. In these computations the precompiler is able to vectorize arithmetic operations over the entire array, rather than over individual dimensions, thus generating relatively long vectors. This vectorization is done, whenever possible, without using expensive gather operations. When gather operations must be used the precompiler attempts to minimize them by making one gather serve for several operands through the use of masks and offsets.

Overview of Testing of Numerical Software

The purposes of program testing are to expose errors; to insure that standards for portability, robustness, etc. are met; and to evaluate performance. A selection of work in these three applications of program testing is presented here.

Computer Science Programs at Universities Awarding the Ph.D. Degree

This paper discusss on the Computer Science Programs at Universities Awarding the Ph.D. Degree