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Presents several letters to the editor about the computing machinery. Dissatisfaction with the quality and nature of the average technical paper presented at the Joint Computer Conferences; Comment on the article "One-Pass Compilation of Arithmetic Expressions for a Parallel Processor," by Harold S. Stone; Use of a coordinate system or characteristic indices for the progress of an algorithm.

The article presents several research papers relating to algorithms. The paper "Greatest Common Divisor of n Integers and Multipliers" presents an algorithm which calculates the greatest common divisor, IGCD, of n integers. Details of the method and comparisons to other algorithms are also given. The algorithm is a new version of the Euclidean algorithm for n integers. The n-1 calculations of the greatest common divisor of two integers is accomplished by means of a modified version of the Blankinship algorithm. The paper "Exponential Integral Ei (x)" presents the results of one phase of research carried out at the Jet Propulsion Laboratory, California Institute of Technology, under Contract NAS7-100, sponsored by the National Aeronautics and Space Administration. It presents an algorithm which was compiled and executed without any modification on a UNIVAC 1108 computer. An unfortunate precedent has been set in several recent algorithms of using an illegal FORTRAN construction.

As part of an effort to design and implement a Fortran compiler on the ILLIAC IV, an extended Fortran, called IVTRAN, has been developed. This language provides a means of expressing data and control structures suitable for exploiting ILLIAC IV parallelism. This paper reviews the hardware characteristics of the nine and singles out unconventiona features which could be expected to influence langluage (and compiler) design. The implications of these features for data layout and algorithm structure are discussed, and the conclusion is drawn that data allocation rather than code structuring is the crucial ILLIAC optimization problem. A satisfactory method of data allocation is then presented. Language structures to utilize this storage method and express parallel algorithms are described. [ABSTRACT FROM AUTHOR]

Describes a computer program for the implementation of graph algorithms which wins Shannon Switching Games. Difference in the goals between players of the game; Existence of a winning strategy between players; Effect of ease of communication between players on computer program demonstration.

Raster scan computer graphics with"real time" character generators have previously been limited to alphanumeric characters. A display has been described which extends the capabilities of this organization to include general graphics. Two fundamentally different scan conversion algorithms which have been developed to support this display are presented. One is most suitable to non- interactive applications and the other to Interactive applications. The algorithms were implemented in Fortran on the CDC6400 computer. Results obtained from the implementations show that the non interactive algorithms can significantly reduce display file storage requirements at little cost in execution time over that of a conventional raster display. The interactive algorithm can improve response time and reduce storage requirements. [ABSTRACT FROM AUTHOR]

The application of Kuhn's Hungarian Method to the problem of matrix reduction as needed in Gotlieb's method for timetable generation is described. The method is suited to both hand and computer calculation. Devices to improve the efficiency of the basic algorithm are discussed. [ABSTRACT FROM AUTHOR]

This article describes a computer procedure used for determining the total or partial inclusion of arbitrarily given points and lines with respect to a set of general polygonal domains which partition a plane bounded region. A feasible computer procedure is described for determining the total or partial inclusion of arbitrarily given points and lines with respect to a set of general polygonal domains which partition a plane bounded region. A scheme for the computer representation of the boundaries of the domains and an algorithm, based on this scheme, for evaluating the inclusion relations are specified in detail. The method employs several levels of selection criteria for the purpose of reducing the number of accesses to auxiliary storage devices and the amount of boundary data for which processing is required. Although it is sometimes possible to utilize the special properties of the domains and their defining boundaries in effecting these determinations, a sufficiently general and flexible solution will usually depend on some type of explicit representation of the boundaries internally stored in the computer. Consequently, a representation is desired which will minimize storage accesses and provide the means for rapid evaluation of the above inclusion relations.

Presents several letters to the editor referencing articles that were published in the previous issues of the journal "Communications of the ACM." "Implementing Phrase-Structure Productions in PL/I," which focused on a PL/I program for-randomly generating terminal strings of a BNF language; Computation that was done in FORTRAN on CDC 6400 in single precision; "On Compiling Algorithms for Arithmetic Expressions,"which focused on an algorithm on the compilation of arithmetic expressions; Objections to the choice of Ljubljana, Yugoslavia as the site for International Federation for Information Processing Congress 1971.