Studies in the design and implementation of programming languages for symbol manipulation

Compared with the development of computing hardware, the development of programming languages has followed a different course. Hardware innovations such as the use of transistors and integrated circuitry have resulted in machines with very substantially improved capabilities, making older machines and even comparatively modern machines obsolescent. The programming languages currently in most widespread use, however, remain those which were already in use as many as ten years ago, namely HJRTRAN, ALGOL 60, and COBOL. Nevertheless, considerable improvements can be made to these languages. The reasons why no improvements were made appear to be primarily twofold. Firstly, they are regarded as 'standard' languages, which in order to facilitate transferability of programs, has made them virtually immutable. Secondly, they can be employed in almost all programming situations without the need for change. Instead, very many other languages have been designed and implemented with particular objectives in view, but which almost invariably limit their application to a narrow field. Only recently have attempts been made to unify some of the developments under the cloak of a single language ( PL/1 and ALGOL 68 ). Data structures are a particular example of what features have been incorporated. There are still considerable omissions however. For instance, neither language has incorporated list processing or symbol manipulation facilities within its basic framework. The latter seems to be most surprising. With the increased capabilities of modern computers and the consequent broadening of their range of application, techniques involving symbol manipulation are becoming increasingly important. Natural language processing such as the analysis of texts for authorship and mechanical translation, and formal manipulations, such as those involved in mechanical theorem-proving and algebraic formula manipulation are some obvious applications. The last mentioned, that of algebraic manipulation of formulae, is one of the most important applications. Several systems, notably R3RMAC, have been developed for this purpose. With the advent of multi-access computing systems a much greater interaction between man and machine is becoming possible, where the advantages of algebraic manipulation and mathematical assistance packages are felt the greatest. This, further, demonstrates the need for symbol manipulation facilities to be available together with normal arithmetic facilities in a programming language, for not only must the formulae be manipulated but also they must be evaluated in normal arithmetic terns. This combination has not completely satisfactorily been acheived in any languages developed in the past. The present investigation is an attempt to overcome this deficiency. A language called ASTRA has been the result. Before discussing the design and implementation of ASTRA, several existing languages are examined in order to discern the desirable properties of a language for symbol manipulation. It is the belief of the present author that the features of ASTRA described herein represent an advance on previous languages. The methods used in the ASTRA compiler are also described

Commentary on a British Geological Survey Computing Archive (1965-85)

An account of the emergence of computer methods in geology, as a background to a restricted archive of documents which chronicle their application in the British Geological Survey

Long-term design of electrical power distribution networks

It is felt that the two-stage design approach may, for certain long-term design problems, provide a useful compromise between methods of exhaustive or intuitive search, and methods in which the problem is viewed purely in terms of the mathematics of optimisation.The first design study has given encouraging results, but a much more intensive investigation is required. Continued development is particularly necessary in the design phase of the program. It is recommended that this should be directed towards a study of future system growth, rather than retrospective studies.It is possible that the full potential of this approach to long -term design can only be fully realised in conjunction with a powerful "on- line" computing system incorporating good visual input /output facilities

Study of disturbed boundary layers using a hot-wire anemometer

One of the most important problems in fluid mechanics which has attracted the interest of investigators for many years is the transition from laminar to turbulent flow. This problem is of greatest importance in practice for flows over aerofoils and in closed channels, where the effects of transition are marked. Little is known, however, about the fundamental physical processes which cause a laminar flow to break down to turbulence. The particular case of boundary-layer flow has received considerable attention and has been treated with some measure of success. Linearized theories have been useful in predicting the nature of the mechanism of instability of a laminar flow; but the non-linear problem, namely, the transition from an unstable laminar to a fully developed turbulent flow, presents formidable mathematical difficulties, so that few theoretical results have been obtained. The development of air and water tunnels together with improved measuring techniques in fluid flow has led to attempts by engineers and experimental physicists to relate the unstable laminar to the turbulent flow regime. The aim of the work reported in this thesis was to gain further insight into the mechanism of transition in the boundary layer. The present experimental work was confined to the simplest example, the flow of an incompressible fluid along a smooth flat plate at zero angle of incidence with zero pressure gradient in the flow direction. The intention was to develop a hot -wire anemometer system to study the downstream development of disturbances introduced under controlled conditions into the boundary layer. As the work progressed emphasis was placed on one particular aspect of the non- linear development of the disturbances, the generation of higher harmonics of the fundamental wave

A proposed translator writing system language - Computer project, volume 3, no. 1

Programming language for advanced translator writing syste

The analysis and simulation of multi-access computer systems

Digitisation of this thesis was sponsored by Arcadia Fund, a charitable fund of Lisbet Rausing and Peter Baldwin

Tactical Electronics Simulation Test System : Feasibility Assessment Briefing CDRL A003, B002

This volume entirely consists of viewgraphs used to present feasibility assessment contained in related volume, Feasibility assessment report CDRL A002