TROLL(ID:630/tro002)Array language for econometricsfor Time-shared Reactive On-Line Laboratory Array language for continuous simulation, econometric modeling, statistical analysis. Structures: Related languages
References: A language for building and testing models (linear or nonlinear simultaneous equation systems), especially econometric models. Language is statement oriented for interactive use. Capabilities include: continuous simulation, major single-equation regression methods, and routine statistical analyses and algebraic transformations of data organized in vectors (e g economic time series) or rectangular arrays (e.g., questionnaire surveys) in ACM Computing Reviews 15(04) April 1974 view details INTRODUCTION In the middle sixties there was a revolution in behavioral science computing brought about by the introduction of software systems, or 'packages', on second and third generation batch equipment (Most notably, BMD, SPSS, OSIRIS, DATA-TEXT). These systems offered the analyst a higher-level language designed specifically for the problems of behavioral science data handling and analysis, thus freeing him from the details of programming, data reformatting and using subroutine libraries. A short time later a number of data-management and analysis systems appeared on time-shared computers. (Most notably, ADMINS, DATANAL, TRACE, IMPRESS, TROLL) These systems seemed to hold further promise for the behavioral scientist wanting to analyze data. An analyst would now be able to interact with his data: to test hypotheses, explore for and formulate new hypotheses, test again and so on. In addition, because of immediate feedback on errors these interactive systems were expected to reduce the learning investment needed to be able to communicate with the computer. Unfortunately, to the broader behavioral science community, the promise of interactive systems is still just that a promise. A number of factors contributed to this situation, among which were: i) time-shared computers were not widely available; 2) the cost of using these interactive systems was high compared with the batch systems; 3) the interactive systems did not, in general, have the breadth of capabilities in both data handling and statistics as the batch systems; and, 4) analysis techniques that took advantage of the power of interactive computing were just beginning to be developed. Going into the middle seventies, we feel the situation is ripe for change. The Cambridge Project is a joint effort by computer scientists, behavioral scientists, and statisticians from M.I.T. and Harvard to bring about the change. Janus is an attempt to provide a powerful interactive data handling and analysis tool for the behavioral scientist. Its design grew out of experience with two interactive systems, ADMINS Mark III and DATANAL, and one batch system, DATA-TEXT. In addition, Janus was influenced by systems and ideas from outside of the behavioral science tradition; for example, the relational data work of S. D. McIntosh and D. M. Griffel and that of E. F. Codd. Janus is one of the subsystems being developed for the Cambridge Project Consistent System (CS). The CS also contains other data analysis programs and subsystems, modeling programs, an urban-planning subsystem, an econometrics analysis subsystem and others. in [ACM] Proceedings of the 1972 Annual Conference of the ACM view details The exact number of all the programming languages still in use, and those which are no longer used, is unknown. Zemanek calls the abundance of programming languages and their many dialects a "language Babel". When a new programming language is developed, only its name is known at first and it takes a while before publications about it appear. For some languages, the only relevant literature stays inside the individual companies; some are reported on in papers and magazines; and only a few, such as ALGOL, BASIC, COBOL, FORTRAN, and PL/1, become known to a wider public through various text- and handbooks. The situation surrounding the application of these languages in many computer centers is a similar one. There are differing opinions on the concept "programming languages". What is called a programming language by some may be termed a program, a processor, or a generator by others. Since there are no sharp borderlines in the field of programming languages, works were considered here which deal with machine languages, assemblers, autocoders, syntax and compilers, processors and generators, as well as with general higher programming languages. The bibliography contains some 2,700 titles of books, magazines and essays for around 300 programming languages. However, as shown by the "Overview of Existing Programming Languages", there are more than 300 such languages. The "Overview" lists a total of 676 programming languages, but this is certainly incomplete. One author ' has already announced the "next 700 programming languages"; it is to be hoped the many users may be spared such a great variety for reasons of compatibility. The graphic representations (illustrations 1 & 2) show the development and proportion of the most widely-used programming languages, as measured by the number of publications listed here and by the number of computer manufacturers and software firms who have implemented the language in question. The illustrations show FORTRAN to be in the lead at the present time. PL/1 is advancing rapidly, although PL/1 compilers are not yet seen very often outside of IBM. Some experts believe PL/1 will replace even the widely-used languages such as FORTRAN, COBOL, and ALGOL.4) If this does occur, it will surely take some time - as shown by the chronological diagram (illustration 2) . It would be desirable from the user's point of view to reduce this language confusion down to the most advantageous languages. Those languages still maintained should incorporate the special facets and advantages of the otherwise superfluous languages. Obviously such demands are not in the interests of computer production firms, especially when one considers that a FORTRAN program can be executed on nearly all third-generation computers. The titles in this bibliography are organized alphabetically according to programming language, and within a language chronologically and again alphabetically within a given year. Preceding the first programming language in the alphabet, literature is listed on several languages, as are general papers on programming languages and on the theory of formal languages (AAA). As far as possible, the most of titles are based on autopsy. However, the bibliographical description of sone titles will not satisfy bibliography-documentation demands, since they are based on inaccurate information in various sources. Translation titles whose original titles could not be found through bibliographical research were not included. ' In view of the fact that nany libraries do not have the quoted papers, all magazine essays should have been listed with the volume, the year, issue number and the complete number of pages (e.g. pp. 721-783), so that interlibrary loans could take place with fast reader service. Unfortunately, these data were not always found. It is hoped that this bibliography will help the electronic data processing expert, and those who wish to select the appropriate programming language from the many available, to find a way through the language Babel. We wish to offer special thanks to Mr. Klaus G. Saur and the staff of Verlag Dokumentation for their publishing work. Graz / Austria, May, 1973 in [ACM] Proceedings of the 1972 Annual Conference of the ACM view details I. Introduction The National Bureau of Economic Research provides a national network for interactive research in economics. This network, known as NBERNET, allows one the use of a computer system called TROLL, which was created at M.I.T. The name is an acronym for Time-shared Reactive On-Line Laboratory, and a detailed description may be found in [2]. The TROLL system consists of a set of tasks which allows the user a rather wide range of research possibilities. For example, the user may create a model file consisting of the syntactic description of one or more model equations, each of which may or may not be linear. Of the many possible models that the user may create within the TROLL model editing task, which is known as MODEDIT, one common model is the following discrete linear regulator: Xi+ I - X i = AX i + BU i + CZ i , X 0 = { , i = 0, i, ... , N-I (1) where, at each time step i, X i is an n-dimensional state vector (which is unknown for i > i), U i is an r-dlmenslonal control vector, Z i is a k-dlmensional vector of known values (often called exogenous variables), and A, B, and C are coefficient matrices. This model is so common that it seems worthwhile to provide the user with a more efficient way to create it than to call directly upon the MODEDIT task, and then to proceed to tediously describe each of the n equations implicit in eq. (i). It is the purpose of this paper to describe the vehicle by which this service can be provided, along with other research possibilities. Extract: The TROLL Macro Facility The TROLL Macro Facility Normally TROLL receives and evaluates commands directly from a demand terminal. However, these commands may be stored, and by typing a single entry at a later date, retrieved and delivered to TROLL for execution. The storage medium are files known as macros, which are described in [3] and [4]. Macro files, when implemented by the user, may be designed in such a way as to interact with that user. The macro may issue a prompt for certain specific information. This prompt may be in the form of a question printed at the user's terminal. Once the user has entered the requested information, the macro may process it. In addition, the macro may be designed to test the information for correctness and completeness before continuing processing. Decisions, branching, looping, and other features available in common programming languages are also available within the TROLL macro facilities. We will now describe some macros which are being developed, and an example is provided to show what occurs while these macros are being used. Extract: The Macro LMEDIT 3. The Macro LMEDIT By entering the command &LMEDIT, the user calls upon a macro which creates the model described by eq. (i). First, the macro LMEDIT requests the name to be applied to the model. Then the macro requests the values of n, r, and k, needed in eq. (i). Next the macro requests the names for each of the variables in the model. This concludes the first stage. The second part of LMEDIT is a description of the coefficients for the matrices A, B, and C in the form of "bit maps." Each entry in these matrices can be one of three types. A prompt is made of the user for a description of each entry type. If the user enters a O, then the coefficient in question is to be zero. An entry of 1 means the coefficient is unknown and must be estimated later by regression analysis. If a 2 is entered this means that the user wishes to specify a non-zero constant value for the coefficient. Once the coefficients have been described to the macro,LMEDIT, the final part is started. LMEDIT will call upon the MODEDIT task, and it will create the model described by eq. (i) and issue the proper commands for saving the model in a file. Control at this point is returned to the user, which is the termination of the processing of LMEDIT. As an example, suppose the user has a model in mind in which n = 3, r ffi 2, and k ffi i. These values would be given to LMEDIT along with the names of the variables in question; suppose the state variables are to be named XI, X2, and X3, the control variables are UI and U2, and the exogenous variable is El. Next, the user would enter the following bit maps for the matrices A, B, and C: A = (!00 1 0 2 1 B= C= Following the bit maps, LMEDIT would request the values of a32 and c31; suppose a32 ffi -3.87 and c31 = 0.5. Once all of this information has been given to LMEDIT, then the following equations would be generated and saved in a model file: Xli+ I - XI i = allXl i + bllUl i + CllZl i X2i+ I - X2 i = a22X2 i + b22U2 i X3i+ I - X3 i = -3.87X2 i + a33X3 i + b31Ul i + b32U2 i + 0.SZI i in [ACM] Proceedings of the annual ACM conference 1976 , Houston, Texas, United States view details in SIGPLAN Notices 13(11) Nov 1978 view details |