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Communications of the ACM

Table of Contents


Letter from the ACM vice-president: “there is a tide in the affairs of men…”


Loader standardization for overlay programs

The overlay capability is described for four of the third generation computer systems: CDC-6000, GE-635, IBM-360, and UNIVAC-1108. A critique of the first three sytems is based on actual experience with a large overlaid trajectory …

A modular computer sharing systems

An alternative approach to the design and organization of a general purpose interactive multiterminal computing system is presented. The system organization described is a conceptually simple arrangement of a bank of interchangeable …

The choice of base

A digital computer is considered, whose memory words are composed of N r-state devices plus two sign bits (two state devices). The choice of base &bgr; for the internal representation of floating-point numbers on such a computer&bgr; …

Algorithm 355: an algorithm for generating ising configurations [Z]


Algorithm 356: a prime number generator using the treesort principle [A1]


Algorithm 357: an efficient prime number generator [A1]


Algorithm 358: singular value decomposition of a complex matrix [F1, 4, 5]


Remark on algorithm 304 [S15]: normal curve integral


A new method for determining linear precedence functions for precedence grammars

The precedence relations of a precedence grammar can be precisely described by a two-dimensional precedence matrix. Often the information in the matrix can be represented more concisely by a pair of vectors, called linear precedence …

The IITRAN programming language

The IITRAN language, developed to be used by students, and its important features are described. IITRAN is a procedure-oriented language with a one-level block structure and a variety of data types. Several novel and powerful …

An axiomatic basis for computer programming

In this paper an attempt is made to explore the logical foundations of computer programming by use of techniques which were first applied in the study of geometry and have later been extended to other branches of mathematics. …

An ambiguity in the description of ALGOL 60

When Algorithm 355 [Comm. ACM 12 (Oct. 1969), 562] was originally submitted to the Algorithms Department it contained a construct which pointed up an ambiguity in the description of ALGOL 60 [Revised Report on the Algorithmic …

Minimax logarithmic error

In this note we point out how rational approximations which are best with respect to maximum logarithmic error can be computed by existing algorithms. Let y be a quantity that we wish to approximate and y be an approximation, …

Retrieval times for a packed direct access inverted file

This note extends the results obtained by Thomas C. Lowe [1] for the case where the list file is stored in packed form. The notation and terminology used were established by Lowe. In addition, we define F(j) = ∑j-1i=1 ƒ(i) and …

A comment on optimal tree structures

In Y.N. Patt's paper “Variable Length Tree Structures Having Minimum Average Search Time” [Comm. ACM 12 (Feb. 1969)], the tree structures obtained are not actually optimal with respect to the two-dimensional chaining devised  …