RLISP(ID:4020/rli001)Lisp without bracketsReduce LISP- Lisp without brackets and Algolish sytax created to write the improved Reduce 2 Related languages
References: Extract: Introduction Introduction Students and faculty at the University of Utah have invested large amounts of energy implementing interpreters for the Burroughs 1700 - 1800 computer series. To date, these have been implemented in the Burroughs Micro Implementation Language (MIL) which has most of the inadequacies associated with order code level assemblers. The lead time between conceptualization of an interpreter and a debugged product has varied from a month to several years. The source code of these programs is usually quite illegible, adequately discouraging student experimentation and participation in projects involving interpreters. Implementation of experimental interpreters is not a task lightly undertaken. A number of research projects were not able to take advantage of microcoded interpreters, while others have been severely hampered by the deficiencies of the microcode assembler. The following are the most significant problems in working directly with microcode for the B1800. 1. The allocation of the large number of registers with varying purposes and degrees of access is the most significant problem facing the microcoder. None of the over 50 addressable registers can be considered as truly "general purpose". Many are devoted to single function and have very restricted access. The asymmetric nature of the instruction set also forces the interpreter writer to spend an unreasonable length of time coding. 2. MIL's primitive macro facility does not permit conditional assembly. 3. A major source of error is that the effect of a macro may extend to registers not explicit in the macro invocation. 4. The defined field addressing capability of the B1800 allows almost any addressing scheme. This flexibility leads to obscure code for interpreters that implement several addressing modes. 5. Input/Output from microcode is extremely difficult. Large amounts of microcode and complicated data structures are required for communication with the MCP (Master Control Program). Methods of rectifying these problems have been attempted with varying degrees of success: 1. SMACK is an I/O and debugging package which is implemented as macros for the portable macro generator STAGE2. It places most of the microcoding burden on the programmer. 2. BIOPSI is a package of routines and macros for communicating with the MCP. A related package implementing virtual memory and paging is available as a replacement for S-memory (secondary memory) access. The packages significantly ease the burden of I/O programming in MIL, but does not provide assistance anywhere else. 3. MMACRO is a front end macro processor for MIL which allows the user to create macros more powerful than those of SMACK or those allowed by MIL. However, the user is still faced with implementing complicated MIL macros and code. None of these packages is a complete solution to the problem. At best they relieve the user of the details of communication with the MCP and provide simple aids for looking at the contents of registers and storage. An alternative to writing microcode is to implement experimental interpreters in a high level language provided with the machine, the Burroughs Software development LANGUAGE. This approach "has proved to be prohibitive in machine time and resources. Comparisons of an interpreter for Standard LISP implemented in SDL and a similar interpreter implemented in MIL showed that the MIL version ran at worst I0 times faster, and at best over 50 times faster than the SDL version. A "compiler language" is the obvious choice for implementing experimental interpreters. Coding in a high level language is more likely to produce working interpreters than hand coding. High level control and data access constructs help remove the onerous burden of the MIL programming environment. We designed a language with features most useful for implementing interpreters for the Burroughs 1800. To take advantage of the high speed scratchpad registers of the B1800 there are 20 special "$ variables". References to these may be freely mixed with references to global variables resident in the S-memory. Access to these global quantities automatically produces the code necessary to move the data to and from the internal registers and secondary storage. Subscripted variables provide automatic access to indexed positions in this global secondary storage. Microcoded subroutines are important to the functioning of most interpreters. The compiler supports procedures in which call by value parameters are allocated to fast scratchpad registers. With the use of two internal stacks, nested and recursive calls are possible. If so specified the scratchpads may be used by a procedure without modifying their global value. Procedures may also be used as functions returning values which can be used in expressions. Secondary storage of programs and data moves randomly about reflecting the needs of the system at any given time. The code generated by our compiler performs the appropriate computations and adjustments transparently so that secondary storage appears static to the user. The source code of a properly structured interpreter is much easier to understand than that of one hand coded in MIL. A micro processor interpreter is only a few pages long as opposed to the 10 to 20 previously required. As the output of the compiler is MIL source language statements, hand optimization of critical sections is possible. in Proceedings of the 12th annual workshop on Microprogramming Hershey, Pennslyvania, United States 1979 view details in Proceedings of the 12th annual workshop on Microprogramming Hershey, Pennslyvania, United States 1979 view details in SIGSAM Bulletin 18(3) August 1984 view details and mote circuit equations, is described. The program is written in RLISP, a LISP-like language in a REDUCE 2 environment. This choice allows a high degree of portability and a possible implementation on a microcomputer. This program starts with a topology and device specification and determines the tree and co-tree of the circuit graph. The circuit is described in terms of topological position of the physical devices. Then each device is split up by an equivalent all-bipolar network with a model selected by the user from a range of implemented models. Second, the program determines the KVL, KCL equations in terms of the variables related by the user to current and voltage in each of the circuit bipolar components. Further, the circuit mote equations are determined, substituting the KVL, KCL equations for the relations, in terms of circuit physical entities (e.g. current, voltage, temperature .... ), implied by the laws of the components. It is possible to resolve this, generally, linear system with one of the methods allowed by REDUCE2, perhaps the simpler is the matrix method with the matrix obtainable with this method is already in its compact form. Whereas the obtained system isn't linear, because one or more components laws are non-linear, the output may be processed with a system that allows non-linear system resolution (e.g. MACSYMA). in European Conference on Computer Algebra EUROCAL 85 LNCS 204 view details in European Conference on Computer Algebra EUROCAL 85 LNCS 204 view details A BRIEF HISTORICAL SKETCH ------------------------- The development of systems for symbolic mathematical computation first became an active area of research and implementation during the decade 1961-1971. . . . . . . To put the decade 1961-1971 into perspective, let us recall that FORTRAN appeared about 1958 and ALGOL in 1960. These two languages were designed primarily for numerical mathematical computation. Then in 1960/1961 came the development of LISP, a language for list processing. LISP was a major advancement on the road to languages for symbolic computation. An operation such as symbolic differentiation which is foreign to FORTRAN and ALGOL is relatively easy in LISP. (Indeed this is one of the standard programming assignments for students first learning LISP.) As will be noted later, several computer algebra systems were written in LISP. 1961-1966 --------- In 1961, James Slagle at M.I.T. wrote a LISP program called SAINT for Symbolic Automatic INTegration. This was one of the earliest applications of LISP to symbolic computation and it was the first comprehensive attempt to program a computer to behave like a freshman calculus student. The program was based on a number of heuristics for indefinite integration and it performed about as well as a good calculus student. One of the first systems for symbolic computation was FORMAC, developed by Jean Sammet, Robert Tobey, and others at IBM during the period 1962-1964. It was a FORTRAN preprocessor (a PL/I version appeared later) and it was designed for the manipulation of elementary functions including, of course, polynomials and rational functions. Another early system was ALPAK, a collection of FORTRAN-callable subroutines written in assembly language for the manipulation of polynomials and rational functions. It was designed by William S. Brown and others at Bell Laboratories and was generally available about 1964. A language now referred to as Early ALTRAN was designed at Bell Laboratories during the period 1964-1966. It used ALPAK as its package of computational procedures. There were two other significant systems for symbolic computation developed during this period. George Collins at IBM and the University of Wisconsin (Madison) developed PM, a system for polynomial manipulation, an early version of which was operational in 1961 with improvements added to the system through 1966. The year 1965 marked the first appearance of MATHLAB, a LISP-based system for the manipulation of polynomials and rational functions, developed by Carl Engelman at M.I.T. It was the first interactive system designed to be used as a symbolic calculator. Included among its many firsts was the use of two-dimensional output to represent its mathematical output. The work of this period culminated in the first ACM Symposium on Symbolic and Algebraic Manipulation held in March 1966 in Washington, D.C. That conference was summarized in the August 1966 issue of the Communications of the ACM. 1966-1971 --------- In 1966/1967, Joel Moses at M.I.T. wrote a LISP program called SIN (for Symbolic Integrator). Unlike the earlier SAINT program, SIN was algorithmic in approach and it was also much more efficient. In 1968, Tony Hearn at Stanford University developed REDUCE, an interactive LISP-based system for physics calculations. One of its principal design goals was portability over a wide range of platforms, and as such only a limited subset of LISP was actually used. The year 1968 also marked the appearance of Engelman's MATHLAB-68, an improved version of the earlier MATHLAB interactive system, and of the system known as Symbolic Mathematical Laboratory developed by William Martin at M.I.T. in 1967. The latter was a linking of several computers to do symbolic manipulation and to give good graphically formatted output on a CRT terminal. The latter part of the decade saw the development of several important general purpose systems for symbolic computation. ALTRAN evolved from the earlier ALPAK and Early ALTRAN as a language and system for the efficient manipulation of polynomials and rational functions. George Collins developed SAC-1 (for Symbolic and Algebraic Calculations) as the successor of PM for the manipulation of polynomials and rational functions. CAMAL (CAMbridge Algebra system) was developed by David Barton, Steve Bourne, and John Fitch at the University of Cambridge. It was implemented in the BCPL language, and was particularly geared to computations in celestial mechanics and general relativity. REDUCE was redesigned by 1970 into REDUCE 2, a general purpose system with special facilities for use in high-energy physics calculations. It was written in an ALGOL-like dialect called RLISP, avoiding the cumbersome parenthesized notation of LISP, while at the same time retaining its original design goal of being easily portable. SCRATCHPAD was developed by J. Griesmer and Richard Jenks at IBM Research as an interactive LISP-based system which incorporated significant portions of a number of previous systems and programs into its library, such as MATHLAB-68, REDUCE 2, Symbolic Mathematical Library, and SIN. Finally, the MACSYMA system first appeared about 1971. Designed by Joel Moses, William Martin, and others at M.I.T., MACSYMA was the most ambitious system of the decade. Besides the standard capabilities for algebraic manipulation, it included facilities to aid in such computations as limit calculations, symbolic integration, and the solution of equations. The decade from 1961 to 1971 concluded with the Second Symposium on Symbolic and Algebraic Manipulation held in March 1971 in Los Angeles. The proceedings of that conference constitute a remarkably comprehensive account of the state of the art of symbolic mathematical computation in 1971. 1971-1981 --------- While all of the languages and systems of the sixties and seventies began as experiments, some of them were eventually put into "production use'' by scientists, engineers, and applied mathematicians outside of the original group of developers. REDUCE, because of its early emphasis on portability, became one of the most widely available systems of this decade. As a result it was instrumental in bringing computer algebra to the attention of many new users. MACSYMA continued its strong development, especially with regard to algorithm development. Indeed, many of the standard techniques (e.g. integration of elementary functions, Hensel lifting, sparse modular algorithms) in use today either came from, or were strongly influenced by, the research group at M.I.T. It was by far the most powerful of the existing computer algebra systems. SAC/ALDES by G. Collins and R. Loos was the follow-up to Collins' SAC-1. It was a non-interactive system consisting of modules written in the ALDES (Algebraic DEScription) language, with a translator converting the results to ANSI FORTRAN. One of its most notable distinctions was in being the only major system to completely and carefully document its algorithms. A fourth general purpose system which made a significant mark in the late 1970's was muMATH. Developed by David Stoutemyer and Albert Rich at the University of Hawaii, it was written in a small subset of LISP and came with its own programming language, muSIMP. It was the first comprehensive computer algebra system which could actually run on the IBM family of PC computers. By being available on such small and widely accessible personal computers, muMATH opened up the possibility of widespread use of computer algebra systems for both research and teaching. In addition to the systems mentioned above, a number of special purpose systems also generated some interest during the 1970's. Examples of these include: SHEEP, a system for tensor component manipulation designed by Inge Frick and others at the University of Stockholm; TRIGMAN, specially designed for computation of Poisson series and written in FORTRAN by W. H. Jeffreys at University of Texas (Austin); and SCHOONSCHIP by M. Veltman of the Netherlands for computations in high-energy physics. Although the systems already mentioned have all been developed in North America and Europe, there were also a number of symbolic manipulation programs written in the U.S.S.R. One of these is ANALITIK, a system implemented in hardware by V. M. Glushkov and others at the Institute of Cybernetics, Kiev. 1981-1991 --------- Due to the significant computer resource requirements of the major computer algebra systems, their widespread use remained (with the exception of muMATH) limited to researchers having access to considerable computing resources. With the introduction of microprocessor-based workstations, the possibility of relatively powerful desk-top computers became a reality. The introduction of a large number of different computing environments, coupled with the often nomadic life of researchers (at least in terms of workplace locations) caused a renewed emphasis on portability for the computer algebra systems of the 1980's. More efficiency (particularly memory space efficiency) was needed in order to run on the workstations that were becoming available at this time, or equivalently, to service significant numbers of users on the time-sharing environments of the day. This resulted in a movement towards the development of computer algebra systems based on newer "systems implementation'' languages such as C, which allowed developers more flexibility to control the use of computer resources. The decade also marked a growth in the commercialization of computer algebra systems. This had both positive and negative effects on the field in general. On the negative side, users not only had to pay for these systems but also they were subjected to unrealistic claims as to what constituted the state of the art of these systems. However, on the positive side, commercialization brought about a marked increase in the usability of computer algebra systems, from major advances in user interfaces to improvements to their range of functionality in such areas as graphics and document preparation. The beginning of the decade marked the origin of MAPLE. Initiated by Gaston Gonnet and Keith Geddes at the University of Waterloo, its primary motivation was to provide user accessibility to computer algebra. MAPLE was designed with a modular structure: a small compiled kernel of modest power, implemented completely in the systems implementation language C (originally B, another language in the "BCPL family'') and a large mathematical library of routines written in the user-level MAPLE language to be interpreted by the kernel. Besides the command interpreter, the kernel also contained facilities such as integer and rational arithmetic, simple polynomial manipulation, and an efficient memory management system. The small size of the kernel allowed it to be implemented on a number of smaller platforms and allowed multiple users to access it on time-sharing systems. Its large mathematical library, on the other hand, allowed it to be powerful enough to meet the mathematical requirements of researchers. Another system written in C was SMP (Symbolic Manipulation Program) by Stephen Wolfram at Caltech. It was portable over a wide range of machines and differed from existing systems by using a language interface that was rule-based. It took the point of view that the rule-based approach was the most natural language for humans to interface with a computer algebra program. This allowed it to present the user with a consistent, pattern-directed language for program development. The newest of the computer algebra systems during this decade were MATHEMATICA and DERIVE. MATHEMATICA is a second system written by Stephen Wolfram (and others). It is best known as the first system to popularize an integrated environment supporting symbolics, numerics, and graphics. Indeed when MATHEMATICA first appeared in 1988, its graphical capabilities (2-D and 3-D plotting, including animation) far surpassed any of the graphics available on existing systems. MATHEMATICA was also one of the first systems to successfully illustrate the advantages of combining a computer algebra system with the easy-to-use editing features on machines designed to use graphical user-interfaces (i.e. window environments). Based on C, MATHEMATICA also comes with its own programming language which closely follows the rule-based approach of its predecessor, SMP. DERIVE, written by David Stoutemyer and Albert Rich, is the follow-up to the successful muMATH system for personal computers. While lacking the wide range of symbolic capabilities of some other systems, DERIVE has an impressive range of applications considering the limitations of the 16-bit PC machines for which it was designed. It has a friendly user interface, with such added features as two-dimensional input editing of mathematical expressions and 3-D plotting facilities. It was designed to be used as an interactive system and not as a programming environment. Along with the development of newer systems, there were also a number of changes to existing computer algebra systems. REDUCE 3 appeared in 1983, this time with a number of new packages added by outside developers. MACSYMA bifurcated into two versions, DOE-MACSYMA and one distributed by SYMBOLICS, a private company best known for its LISP machines. Both versions continued to develop, albeit in different directions, during this decade. AXIOM, (known originally as SCRATCHPAD II) was developed during this decade by Richard Jenks, Barry Trager, Stephen Watt and others at the IBM Thomas J. Watson Research Center. A successor to the first SCRATCHPAD language, it is the only "strongly typed'' computer algebra system. Whereas other computer algebra systems develop algorithms for a specific collection of algebraic domains (such as, say, the field of rational numbers or the domain of polynomials over the integers), AXIOM allows users to write algorithms over general fields or domains. As was the case in the previous decade, the eighties also found a number of specialized systems becoming available for general use. Probably the largest and most notable of these is the system CAYLEY, developed by John Cannon and others at the University of Sydney, Australia. CAYLEY can be thought of as a "MACSYMA for group theorists.'' It runs in large computing environments and provides a wide range of powerful commands for problems in computational group theory. An important feature of CAYLEY is a design geared to answering questions not only about individual elements of an algebraic structure, but more importantly, questions about the structure as a whole. Thus, while one could use a system such as MACSYMA or MAPLE to decide if an element in a given domain (such as a polynomial domain) has a given property (such as irreducibility), CAYLEY can be used to determine if a group structure is finite or infinite, or to list all the elements in the center of the structure (i.e. all elements which commute with all the elements of the structure). Another system developed in this decade and designed to solve problems in computational group theory is GAP (Group Algorithms and Programming) developed by J. Neubueser and others at the University of Aachen, Germany. If CAYLEY can be considered to be the "MACSYMA of group theory,'' then GAP can be viewed as the "MAPLE of group theory.'' GAP follows the general design of MAPLE in implementing a small compiled kernel (in C) and a large group theory mathematical library written in its own programming language. Examples of some other special purpose systems which appeared during this decade include FORM by J. Vermaseren, for high energy physics calculations, LiE, by A.M. Cohen for Lie Algebra calculations, MACAULAY, by Michael Stillman, a system specially built for computations in Algebraic Geometry and Commutative Algebra, and PARI by H. Cohen in France, a system oriented mainly for number theory calculations. As with most of the new systems of the eighties, these last two are also written in C for portability and efficiency. Research Information about Computer Algebra ------------------------------------------- Research in computer algebra is a relatively young discipline, and the research literature is scattered throughout various journals devoted to mathematical computation. However, its state has advanced to the point where there are two research journals primarily devoted to this subject area: the "Journal of Symbolic Computation" published by Academic Press and "Applicable Algebra in Engineering, Communication and Computing" published by Springer-Verlag. Other than these two journals, the primary source of recent research advances and trends is a number of conference proceedings. Until recently, there was a sequence of North American conferences and a sequence of European conferences. The North American conferences, primarily organized by ACM SIGSAM (the ACM Special Interest Group on Symbolic and Algebraic Manipulation), include SYMSAM '66 (Washington, D.C.), SYMSAM '71 (Los Angeles), SYMSAC '76 (Yorktown Heights), SYMSAC '81 (Snowbird), and SYMSAC '86 (Waterloo). The European conferences, organized by SAME (Symbolic and Algebraic Manipulation in Europe) and ACM SIGSAM, include the following whose proceedings have appeared in the Springer-Verlag series "Lecture Notes in Computer Science": EUROSAM '79 (Marseilles), EUROCAM '82 (Marseilles), EUROCAL '83 (London), EUROSAM '84 (Cambridge), EUROCAL '85 (Linz), and EUROCAL '87 (Leipzig). Starting in 1988, the two streams of conferences have been merged and they are now organized under the name ISSAC (International Symposium on Symbolic and Algebraic Computation), including ISSAC '88 (Rome), ISSAC '89 (Portland, Oregon), ISSAC '90 (Tokyo), ISSAC '91 (Bonn) and ISSAC '92 (Berkeley). ----------------------------------------------- Professor Keith Geddes Symbolic Computation Group Department of Computer Science University of Waterloo Waterloo ON N2L 3G1 CANADA in European Conference on Computer Algebra EUROCAL 85 LNCS 204 view details |