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Communications of the ACM

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This Gulliver is no fiction!


Reconstruction of pictures from their projections

There are situations in the natural sciences and medicine (e.g. in electron microscopy and X-ray photography) in which it is desirable to estimate the gray levels of a digital picture at the individual points from the sums of …

Algorithmic selection of the best method for compressing map data strings

The best of a dozen different methods for compressing map data is illustrated. The choices are generated by encoding data strings—sequence of like codes—by three methods and in four directions. Relationships are developed between …

Retrieval—Update speed tradeoffs using combined indices

In a paper in the November 1970 Communications of the ACM, V.Y. Lum introduced a technique of file indexing named combined indices. This technique permitted decreased retrieval time at the cost of increased storage space. This …

Implementation of the substring test by hashing

In a paper in the November 1970 Communications of the ACM, V.Y. Lum introduced a technique of file indexing named combined indices. This technique permitted decreased retrieval time at the cost of increased storage space. This …

BLISS: a language for systems programming

A language, BLISS, is described. This language is designed so as to be especially suitable for use in writing production software systems for a specific machine (the PDP-10): compilers, operating systems, etc. Prime design goals …

New LISP techniques for a paging environment

The system described herein employs the block concept, and that of global and local variables, in addition to the methods applied in most LISP systems. Also, a new means of list representation is used: “local sequential” for  …

A note on “A modification of Nordsieck's method using an ‘Off-Step’ point”

An examination was made of the experimental results presented by J.J. Kohfeld and G.T. Thompson [1] in their paper on a modification of Nordsieck's method for the numerical solution of ordinary differential equations, using a …

Rapid computation of general interpolation formulas and mechanical quadrature rules

Let ƒ have n continuous derivatives on a closed interval [a, b] and let L be a linear functional. The attempt is made to approximate L(ƒ) with L(Q) where Q is a polynomial, approximating ƒ. Algorithms are developed for rapidL …

An extension of the Munkres algorithm for the assignment problem to rectangular matrices

The assignment problem, together with Munkres proposed algorithm for its solution in square matrices, is presented first. Then the authors develop an extension of this algorithm which permits a solution for rectangular matrices …

Algorithm 415: Algorithm for the assignment problem (rectangular matrices)

This algorithm is a companion to [3] where the theoretical background is described.

Algorithm 416: Rapid computation of coefficients of interpolation formulas

This algorithm is a companion to [1] where the theoretical background is described

Algorithm 417: Rapid computation of weights of interpolatory quadrature rules

This algorithm is a companion to [1] where the theoretical background is described

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