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Communications of the ACM

Table of Contents

ACM president's letter: NATO and software engineering?

Letters to the editor: “ACM has a tremendous story to tell”

Letters to the editor: response to Galler, Pinkerton, Arden letter

Letters to the editor: comment on a paper by Ku and Adler

Letters to the editor: on selecting the sites for IFIP congresses

Letters to the editor: move ACM 1971 conference from Chicago?

Letters to the editor: on obtaining technical information from the federal government

Letters to the editor: a graduated dues structure for ACM

Letters to the editor: restore professional atmosphere at ACM meetings

Degree of multiprogramming in page-on-demand systems

A simple stochastic model is described which offers a base for understanding the relationship between the number of programs permitted to share memory (the degree of multiprogramming), drum traffic rates, and central processing …

Three-dimensional computer display

A stereographic display terminal has been produced using the raster display (BRAD) recently developed at Brookhaven. The system uses a rotating refresh memory to feed standard television monitors. To produce a stereographic display …

Simulation of traffic flows in a network

A computer simulation program which deals with traffic flows in the network of a large area is described. Each road is segmented into blocks of several ten-meter lengths and is represented by a bidirectional list in computer  …

Introducing computing to smaller colleges and universities—a progress report

By technical means that are now routine, computer service for smaller colleges and universities can be provided by remote terminals of a central facility. Access, however, is not enough—effective organizational and educational …

Algorithm 351: modified Romberg quadrature

Certification of algorithm 298 [F1]: determination of the square root of a positive definite matrix

Certification of algorithm 328 [F4]: Chebyshev solution to an overdetermined linear system

Certification of algorithm 302 [K2]: transpose vector stored array

Spline function methods for nonlinear boundary-value problems

The solution of the nonlinear differential equation Y″ = F(x, Y, Y′) with two-point boundary conditions is approximated by a quintic or cubic spline function y(x). The method is well suited to nonuniform mesh size and dynamic …

A recursive relation for the determinant of a pentadiagonal matrix

A recursive relation, relating leading principal minors, is developed for the determinant of a pentadiagonal matrix. A numerical example is included to indicate its use in calculating eigenvalues.

Generation of optimal code for expressions via factorization

Given a set of expressions which are to be compiled, methods are presented for increasing the efficiency of the object code produced by first factoring the expressions, i.e. finding a set of subexpressions each of which occurs …

A computer system for transformational grammar

A comprehensive system for transformational grammar has been designed and implemented on the IBM 360/67 computer. The system deals with the transformational model of syntax, along the lines of Chomsky's Aspects of the Theory. …

An anomaly in space-time characteristics of certain programs running in a paging machine

The running time of programs in a paging machine generally increases as the store in which programs are constrained to run decreases. Experiment, however, have revealed cases in which the reverse is true: a decrease in the size …