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Communications of the ACM

Table of Contents

ACM president's letter: NATO and software engineering?

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

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

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  …

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 …

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

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 …