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A technique for computer detection and correction of spelling errors
The method described assumes that a word which cannot be found in a dictionary has at most one error, which might be a wrong, missing or extra letter or a single transposition. The unidentified input word is compared to the dictionary again, testing each time to see if the words match—assuming one of these errors occurred. During a test run on garbled text, correct identifications were made for over 95 percent of these error types.
Computer-made perspective movies as a scientific and communication tool
It is easy to program the basic transformation required for a perspective drawing. This fact plus the advent of high speed microfilm printers such as the General Dynamics Electronics S-C 4020 makes possible perspective movies as the direct output from a computer. The programming of such a movie is briefly described for studying the angular motions of a satellite containing an attitude control system. In the movie, a domino-shaped box represents the satellite and a sphere with circles of latitude and longitude represents the earth. The cost was approximately three to eight minutes of IBM 7090 time per one minute of movie.
Digital data processor for tracking the partially illuminated moon
A study of lunar tracking techniques and fabrication of a breadboard to assess the feasibility of the best technique selected was conducted to define a tracking system for observation of the sightline to the center of a partially illuminated moon. The data processing portion of the system is presented in detail and then described in general are the operation of the tracker head assembly for data readout, the operation of the entire system and the effect data processing considerations have on the design of the tracker system.
The system basically consists of an optical sensor, digital computer and tracker drive mechanism. The three system units, connected in cascade, comprise the control loop. For this application, an optical telescope with a radial mechanical scanning mechanism was used that read out lunar sightline measurement information. This information is sequentially read into a special purpose digital computer that extracts the measurements and computes the error signals that drive the tracker to the appropriate attitude.
report on CCITT data communications study group meeting
Data communications was the subject of a two-week meeting held 24 September through 4 October 1963, in Geneva, Switzerland, by the International Telegraph and Telephone Consultative Committee (CCITT) Special Study Group A. Previous meetings of this group had been held in Geneva in April, 1960, and October, 1961. The CCITT has traditionally been responsible for all standardization activities involving the public telecommunications network of the world. Among the 150 participants, there were eleven USA representatives who represented the Government, various business machine companies and the common carriers.
Tests on a computer method for constructing school timetables
A previously proposed computer method for constructing timetables, based on an iteration involving Boolean matrices, is described. In limited tests the method has successfully produced timetables on every trial. References are given which relate the timetable problem to theorems on matrices of zeros and ones, and to theorems on bipartite graphs. Some problems of applying the method to constructing timetables in real situations are noted.
FORTRAN subroutines for time series data reduction
For several years the author has been concerned with time series data reduction of guided missile data derived from tracking, telemetry and static test instrumentation. The data, which is acquired from many sources and comes in a great variety of formats and coding systems, must commonly be manipulated in a number of general ways before the calculation of functions specific to guided missile analysis is possible. The costs of programming many special purpose data reduction programs and the development time consumed in preparing and checking out these programs have strongly indicated the need for independent, general-purpose computer program modules or subroutines for data reduction. The philosophy arrived at by the author, is almost identical with that described in a recent publication by Healy and Bogert, and in a note by Bennet, but these individual module specifications are concerned with continuous functions, whereas the referenced article deals with spectral analysis.
A general business-oriented language based on decision expressions
The structure of a digital computer programming language which covers a wide class of business and file processing applications is presented. Such a structure, based on identifying and incorporating into a compiler the aspects common to all processes of such class, permits writing extremely compact programs, even for comparatively complex applications, in terms of tables of control expressions which express only information characteristic of the particular application. Furthermore, local changes of a process (e.g. changes affecting only one of the output files involved) can be effected by local modifications in the program (e.g. modification of only one entry of the tables). This structure also allows for inexpensive preparation of loading-speed compilers which translate the source programs into efficient machine codes.
The approach adopted here departs from conventional mechanical language design philosophies. It stresses the structural analysis of the class of processes to be represented in the languages, as opposed to emphasizing formal (i.e., contents-independent) syntactical definitions. It relies exclusively on nonprocedural representation of processes as sets (tables) of relations between data and results (there are no control statements such as GO TO, etc.), instead of using procedure descriptions (which are one-to-one translations of flowcharts). Here an invariant pattern of procedure is identified as characteristic of the class of all batch file processes.
Digital computer determination of alpha source activity
A technique is described for determining the activity and homogeneity of an alpha source. It is believed that the technique, using a digital computer, has many uses and applications in the field of nuclear physics. The technique involves computer manipulation of the digital image of the nuclear source. Experimental details are given.
Floating-point arithmetic with 84-bit numbers
A classic and straightforward technique is presented which is not limited to the size or type of number representation used or multiple precision arithmetic.
A comparative study has been made of a variety of numerical techniques for fitting experimental data of the decay type by forms involving the sums of exponentials. Statistical errors of the fitted parameters are also calculated. These methods have been applied to artificially-generated sets of data as well as to the results of experiments with radioactive tracers on both human and animal subjects. Results show that the values of the fitted parameters are very sensitive to variations in the fitting procedure. Therefore great care must be exercised in identifying such values with physical constants. Although the values of functions derived from these fitted parameters which can definitely be associated with physical entities are generally more stable under variations in the fitting techniques, error bounds can be so large that no great confidence can be placed even in them. It would therefore appear best to select a uniform technique both for running the experiments and for analyzing the data, and then to consider as significant only relative results between one subject and the next.
Computation’s development critical to our society
The ACM's growth continues: we are now at 13,000 members; expenses also grow. Our professional membership does not spring from a uniformly trained group as in mathematics or physics or even economics. Instead, our increasing membership comes from what I might call intellectual adventures—pioneers in an over-organized society—who see great futures in computing at all levels of aspiration.
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