bluuebunny/crossref_metadata_2025 huggingface dataset:
Some properties of variable length packet shapers
Authors: Le Boudec Jean-Yves
Published: January 2007

The min-plus theory of greedy shapers has been developed after Cruz's results on the calculus of network delays. An example of greedy shaper is the buffered leaky bucket controller. The theory of greedy shapers establishes a number of properties; for example, re-shaping keeps original arrival constraints. The existing theory applies in all rigor either to fluid systems, or to packets of constant size such as ATM. For variable length packets, the distortion introduced by packetization affects the theory, which is no longer valid. Chang has introduced the concept of packetizer, which models the effect of variable length packets, and has also developed a max-plus theory of shapers. In this paper, we start with the min-plus theory, and obtain results on greedy shapers for variable length packets which are not readily explained with the max-plus theory of Chang. We show a fundamental result, namely, the min-plus representation of a packetized greedy shaper. This allows us to prove that, under some assumptions, re-shaping a flow of variable length packets does keep original arrival constraints. However, we show on some examples that if the assumptions are not satisfied, then the property may not hold any more. We also demonstrate the equivalence of implementing a buffered leaky bucket controller based on either virtual finish times or on bucket replenishment.
On the performance of multiplexing independent regulated inputs
Authors: Chang Cheng-Shang , Chiu Yuh-ming , Song Wheyming Tina
Published: January 2007

In this paper, we consider the performance analysis problem for a work conserving link with a large number of independent regulated inputs. For such a problem, we derive simple stochastic bounds under a general traffic constraint for the inputs. The bound for queue length is shown to be a stochastic extension of the deterministic worst case bound and it is asymptotically tighter than the bound in Kesidis and Konstantopoulos [23]. We also test the bound by considering periodic inputs with independent starting phases. Based on Sanov's theorem and importance sampling, we propose a fast simulation algorithm that achieves significant variance reduction. The simulations results are compared with our stochastic bound and the bound in [23].
A study of memory system performance of multimedia applications
Authors: Sohoni Sohum , Min Rui , Xu Zhiyong , Hu Yiming
Published: January 2007

Multimedia applications are fast becoming one of the dominating workloads for modern computer systems. Since these applications normally have large data sets and little data-reuse, many researchers believe that they have poor memory behavior compared to traditional programs, and that current cache architectures cannot handle them well. It is therefore important to quantitatively characterize the memory behavior of these applications in order to provide insights for future design and research of memory systems. However, very few results on this topic have been published. This paper presents a comprehensive research on the memory requirements of a group of programs that are representative of multimedia applications. These programs include a subset of the popular MediaBench suite and several large multimedia programs running on the Linux, Windows NT and Tru UNIX operating systems. We performed extensive measurement and trace-driven simulation experiments. We then compared the memory utilization of these programs to that of SPECint95 applications. We found that multimedia applications actually have better memory behavior than SPECint95 programs. The high cache hit rates of multimedia applications can be contributed to the following three factors. Most multimedia applications apply block partitioning algorithms to the input data, and work on small blocks of data that easily fit into the cache. Secondly, within these blocks, there is significant data reuse as well as spatial locality. The third reason is that a large number of references generated by multimedia applications are to their internal data structures, which are relatively small and can also easily fit into reasonably-sized caches.
Fixed point approximations for TCP behavior in an AQM network
Authors: Bu Tian , Towsley Don
Published: January 2007

In this paper, we explore the use of fixed point methods to evaluate the performance of a large population of TCP flows traversing a network of routers implementing active queue management (AQM) such as RED (random early detection). Both AQM routers that drop and that mark packets are considered along with infinite and finite duration TCP flows. In the case of finite duration flows, we restrict ourselves to networks containing one congested router. In all cases, we formulate a fixed point problem with the router average queue lengths as unknowns. Once these are obtained, other metrics such as router loss probability, TCP flow throughput, TCP flow end-to-end loss rates, average round trip time, and average session duration are easily obtained. Comparison with simulation for a variety of scenarios shows that the model is accurate in its predictions (mean errors less than 5%). Last, we establish monotonicity properties exhibited by the solution for a single congested router that explains several interesting observations, such as TCP SACK suffers higher loss than TCP Reno.
Load chracterization and anomaly detection for voice over IP traffic
Authors: Mandjes Michel , Saniee Iraj , Stolyar Alexander
Published: January 2007

We consider the problem of traffic anomaly detection in IP networks. Traffic anomalies arise when there is overload due to failures in a network. We present general formulae for the variance of the cumulative traffic over a fixed time interval and show how the derived analytical expression simplifies for the case of voice over IP traffic, the focus of this paper. To detect load anomalies, we show it is sufficient to consider cumulative traffic over relatively long intervals such as 5 minutes. This approach substantially extends the current practice in IP network management where only the first order statistics and fixed thresholds are used to identify abnormal behavior.
A prototype engineering tester for microcode and hardware debugging
Authors: Sherwood Will
Published: January 2007

A custom test system was developed to assist in the integration of the microcode and components of a VLSI VAX Microcomputer prototype system. Microcode debugging ease (on the hardware) and leverage is gained by hierarchical accumulation of access and execution operations for the prototype. VAX-11 750-computer-based software and custom UNIBUS-interconnect-based tester hardware comprise this Engineering Tester (fondly called ET). Interactively entered high-level commands to ET software communicate with the tester hardware and the prototype through UNIBUS control and data registers. This paper presents a summary of the methodology and CAD verification tools used in designing the VLSI VAX system. the software and hardware architecture of ET. a look at the implementation and at the leverage gained by building ET based on existing software and hardware tools, and finally, a review of ET applications during the debug phase.
Compaction of two-level microprograms for a multiprocessor computer
Authors: Baba Takanobu , Ikeda Mitsuru , Yamazaki Katsuhiro , Okuda Kenzo
Published: January 2007

An optimizing loader has been designed and developed for two-level microprograms of a multiprocessor computer. In the computer, a microinstruction activates nanoprograms in multiprocessors, specifying nanoprogram start address and the processors to be activated. This scheme allows the loader to utilize the same nanoprogram among several microinstructions, which activate it, and compact the nanoaddress space by nanocode movement. The experimental results show that (i) the nanoprogram sizes are reduced from 17.3 to 31.0 % and (ii) the effect of the reduction is proportional to the number of microinstructions.
Improved instruction formation in the exhaustive local microcode compaction algorithm
Authors: Atkins Richard P.
Published: January 2007

An algorithm has been developed to compact the micro-operations of horizontal microcode into optimal segments of straight-line microinstructions. The Quine modified (QM) algorithm generates solutions for 24 micro-operations in 2 sec. of VAX processing time. It generates a small number of solutions. A Pascal program that models the algorithm has been developed. A proof that the algorithm produces a minimal solution is given.
The generation of simulator-based systems for microcode development
Authors: Charlton C C , Jackson D , Leng P H
Published: January 2007

The work described in this paper is directed at the structure and construction of simulator-based systems for the development and testing of microcode. While the value of such software tools is widely recognised, their availability in the early stages of the development cycle of a new machine is subject to the time and effort required for their implementation. We describe here the design of a system to assist in their generation from the specifications of the machine to be simulated. The system is based on the application of generalised program and data structures to facilitate the rapid implementation of an efficient simulation 'nucleus', which is integrated with an 'environment' of machine-independent routines for user interaction with the simulated machine.
Migration implementation by integrating microprogramming and HLL programming
Authors: Heimonen Juha-Matti , Heinanen Juha
Published: January 2007

Implementing vertical migrations involves synthesizing new microcoded instructions from selected parts of HLL programs and loading the microcode into the computer's control memory. Ideally, both of these tasks are done automatically so that programs can be written independently of their actual level of implementation. This paper suggests the integration of microprogramming and HLL programming as a step toward the automation of the migration process. A possible linguistic convention for software/firmware interfacing is presented. Compiling of migrated programs is also discussed and examples are given. Finally, an attempt is made to compare the migration effects to those obtainable by automatic synthesis methods.
SDVS
Authors: Marcus Leo , Crocker Stephen D. , Landauer Jaisook R.
Published: January 2007

This paper is a progress report on an experimental system, the state delta verification system (SDVS), for verifying microcode correctness. The goal of this project is to solve some of the problems, both theoretical and engineering, obstructing the realization of a usable and applicable program for checking proofs of microcode correctness. The ideal result would be a system that could be naturally incorporated into the specification-implementation cycle of, for example, microcoded machine instruction sets.
An axiomatization of low-level parallelism in microarchitectures
Authors: Damm Werner
Published: January 2007

This paper presents the heart of a universal syntax-directed proof system for the verification of horizontal computer architectures.

The system is based on the axiomatic architecture description language AADL, which incorporates a comcise model of clocked microarchitectures. For a given description A of a host architecture, we show how to axiomatize A's microoperations and present powerful proof-rules dealing with the inherent low-level parallelism of horizontal architectures. They allow for a complete axiomatic treatment of the timing behaviour and dynamic conflicts of microprograms written in an A-dependent high-level microprogramming language based on S*.
Some uses of { and }
Authors: Hui Roger
Published: January 2007

We believe that the design of APL was also affected in important respects by a number of procedures and circumstances. Firstly, from its inception APL has been developed by using it in a succession of areas. This emphasis on application clearly favors practicality and simplicity. The treatment of many different areas fostered generalization … — Falkoff and Iverson, “The Design of APL”
System development methodology using LOGOS
Authors: Allen David B. , Dempsey Mark R. , Goldsmith Leslie H.
Published: January 2007

The development of applications written in APL has traditionally both benefited by and suffered from the freedom offered by the environment. A consequence of this freedom is that few applications are designed from the perspectives of consistency, modularity, and structure. This paper describes how LOGOS, a programming environment for APL, helps improve the development and maintenance of APL applications. Through the use of basic support facilities and integrated tools, LOGOS encourages a modular design within applications and a greater consistency among them. The support facilities provide such functionality as the paging of large applications, or the parallel testing of multiple versions of software, with minimal effort.

Specific examples of system design and development are given in the paper. Programming methodologies in widespread practice are examined, and their application to APL with LOGOS is described. The use of LOGOS in top-down design and in application prototyping is also discussed.
Trees as nested arrays and the use of underdisclose
Authors: Nauta G. C.
Published: January 2007

A notation is presented to denote a tree as a vector, using nested arrays. The construction of a tree as well as operations on it, make use of the operator
under
(also called
each
) and the function
disclose
. The definition of a new operator useful for the handling of nested arrays is given.
Automatic generation of graphs from free-form text using APL
Authors: Hill L. Owen , Zein David A.
Published: January 2007

This paper supplements the material of Reference 1. In [1], we describe techniques and algorithms for extracting statistical and numeric data from free-form text files using APL. The files have arbitrary structure. In this paper, we will show sample files, each having its unique structure, and then demonstrate how the APL program generates graphic files in both batch and interactive modes. In the batch mode, the procedure of generating graphic files from free-form text is automated to the extent that minimum human intervention is required. In this mode, hundreds of files with different formats are processed daily. The interactive mode allows the user to modify the data used to drive the graphic part of the program using a full-screen session. The APL program is the 'workhorse' in a VM (virtual Machine) multi-programming environment, where several programs that use different languages interact. For example, in addition to APL2, we use REXX, SCRIPT, GDDM the (Graphical Data Display Manager), FORTRAN, PLI, and XEDIT. The automation is brought about by the use of a network of disconnected virtual machines, also known as service machines, within the IBM network of computers.
APL2 implementations of unification
Authors: Brown James A. , Guerreiro Ramiro
Published: January 2007

This paper defines unification, the pattern matching process used in logic programming, and presents various alternatives for constructing algorithms
FSM—a fullscreen manager
Authors: Busman R. J.
Published: January 2007

FSM is a set of utility functions used in developing fullscreen APL systems at The Upjohn Company. Defining panels and validating input data can be a tedious and time consuming process. FSM simplifies the construction of user dialogues by providing two methods for designing panels, by creating help panels for each screen and input field, and by providing three types of documentation on each panel. It automates checking of user input, scrolling on selected fields, aborting input under program or user signal, and controlling field processing with edit codes, missing values, fill characters, and left/right justification. FSM was originally developed in conjunction with work on a pharmaceutical manufacturing receiving system. The use of nested arrays simplified implementation and contributes to its ease of use. The purpose of the paper will be to describe the capabilities of FSM as influenced by feedback from other development analysts.
A system for compiling fonts
Authors: Howland John E.
Published: January 2007

An interactive system for specifying fonts using an object oriented approach, based on cubic splines, is given. An interactive Bezier curve editor is described as well as systems for compiling bit image fonts from their geometric descriptions and a system for compiling PostScript programs which can be used to render fonts on a PostScript printer or typesetter.
A second generation DOMINO for statisticians
Authors: Sykes Alan
Published: January 2007

The use of 'domino' (⊞) is one of the many attractive features of APL. To a statistician, it is particularly useful in its dyadic form, returning least-squares estimates Y⊞D necessary to predict data in the 'Y' vector using as prediction variables, the columns of the “design matrix” D.

Second generation APL interpreters supporting nested array structures present a unique opportunity to make such dyadic uses of domino even more attractive. The householder algorithm employed by domino provides much information that is lost to the user. This paper discusses how this information can be captured by Y⊞D returning a nested array. The essential ideas are presented using APL functions. An auxiliary processor written in C for the Dyalog interpreter demonstrates an implementation of these ideas.
APL thinking: examples
Authors: Eisenberg Murray , Peelle Howard A.
Published: January 2007

In an effort to understand “APL thinking”, we examine a few selected examples of using APL to solve specific problems, namely: compute the median of a numerical vector; simulate the Replicate function; string search; carry forward work-to-be-done in excess of capacity; rotate concentric rectangular rings in a matrix; find column indices of pivots in an echelon matrix.

These examples are drawn from our teaching experience as well as from APL literature. We are particularly interested in studying thinking processes underlying alternative solutions to such problems — i.e., our goal is to “get inside the head” of the APL programmer. Analyses include reconstructing thoughts, comparing alternative approaches, and, in general, scrutinizing supposed characteristics of APL thinking.
OPERA: options price evaluation and risk analysis system
Authors: Bogart Barry
Published: January 2007

This paper describes a decision-support system written in APL and implemented on a Personal Computer. The purpose of the system is to assist in the management of a portfolio of stock and commodity options, so that exposure to risk will be detected as early as possible and corrective action can be effected. The system incorporates an extended version of the Black-Scholes stochastic model for determining the fair value for an option price and its sensitivity, based on the variables stock and option exercise prices, time, interest rate, and stock price volatility. Option prices and 'deltas' are computed for a range of these variables and saved in an APL database from which they are later combined with stock position information to produce tabular and graphical output showing risk exposure across the dimensions of stock price change and the passage of time.
Frangere..decision support in many dimensions or..how to break the old spread sheet approach
Authors: Barnetson Paul
Published: January 2007

This paper describes FRANGERE, IBM's new technique for providing decision support for the planning and control process. It provides management information from a multi-dimensional data structure which the user can view, along any dimensions, as a series of 'pages' or spread-sheets. The information in this structure can be summarised upwards, 'broken back' downwards, or moved sideways, between files on different computers and in different parts of the world. In addition, the planning information in this multi-dimensional structure can be compared with the 'actual' figures held elsewhere on computer files, and in totally different formats. The package provides full-screen support on coloured screens, full system 'help' facilities, and understandable error messages. It provides a large set of pictorial and tabular reports and is a system which the new user can grow into gradually, learning the more advanced facilities at a speed that matches his desires.
Shared functions and variables as an aid to applications design
Authors: Berry Michael J.A.
Published: January 2007

Analogic APL incorporates true sharing of named objects into APL for the first time. Both functions and variables may be shared. True shared variables are variables which are visible and accessible to multiple tasks without the aid of any intervening processor. They fill roles traditionally taken by shared file systems and (@@@@)SVO-style shared variables. Their straightforward design allows an APL programmer to develop whatever sharing protocol is most appropriate to the application. One could, for example, build a complete shared file system or (@@@@)SVO-style shared variable processor written in APL. All of the features of Analogic APL discussed in this paper have been fully specified. The system is now being implemented. A substantial subset of these features will be demonstrable in Helsinki in June, 1984.
Word, image and metaphor to name APL concepts in many tongues
Authors: Berry Paul , Bach Gottfried , Bouchard Michel , Buch Margarete , Berry Sachiko Ikeuchi , Pesch Roland
Published: January 2007

APL notation uses symbols rather than words. But discussion and education require the use of words. A well-chosen term can make a new concept plain, or link it effectively to related topics. The English-speaking originators of APL took some pains to avoid jargon, and to select terms rooted in metaphors to help convey the meaning of symbols. This paper indentifies several goals in the choice of English terms for APL concepts, and then lists problems that arise when corresponding terms must be found in other languages, with examples from French, German, Spanish and Japanese. It notes both strengths and weaknesses of current APL terminology in English. It exhorts translators and writers in languages other than English to avoid transliterating English terms, and urges them instead to convey the relevant images implied in the English source, or, better yet, to contribute new images to enrich the international vocabulary of APL.
APL two by two-syntax analysis by pairwise reduction
Authors: Bunda J. D. , Gerth J. A.
Published: January 2007

Benkard explains the precedence rules of APL with a syntactic binding hierarchy [1,2]. This paper uses the hierarchy as a basis for developing a more formal description of APL syntax which can be applied directly in a syntax analyzer. The flexibility of this approach makes it useful as a basis for examining the effect of proposed syntax changes and the consequences of previous design choices.
APL application development in a micro system environment
Authors: Flury Jos , Lankhorst Dirk
Published: January 2007

APL on microcomputers is a rapidly expanding area. In order for full-grown applications to be developed on, or easily carried over to microcomputers, it is necessary that tools such as AP124 and AP126 become available on these small systems. In this paper we will describe how we have implemented an emulation of the graphical part of IBM's AP126 and GDDN for APL.68000.
An operator calculus
Authors: Iverson Kenneth E. , Pesch Roland , Schueler J. Henri
Published: January 2007

This paper extends a line of APL development presented in a sequence of papers [1-7] over the past six years. The main topics addressed are the interactions of operators such as rank, composition, derivative, and inverse (i.e., the beginnings of a calculus of operators), a simplification in the complement of attributes tentatively presented in [6], and a treatment of the shapes of individual results (as defined in [7]) in the case of empty frames.

Brief treatments are also given to a number of smaller matters: a
transliteration
or
token substitution
facility, the treatment of niladic functions, a custom (variant) operator, the obsolescence of certain system variables, and some changes in the function definition operator and in the treatment of supernumerary axes.
Polyvalent functions, operators, strand notation and their precedence
Authors: Naugle Richard L. , Schlam Joseph B.
Published: January 2007

Functions and operators that take any number of arguments are proposed. Examples in current APL are shown. Function subvalence and polyvalent defined functions are established. Polyvalent primitive functions respond as follows:

644

(
A A+A
),(
A A+
),
+A A
←2

Current operator usage, operator subvalence, polyvalent defined operators are explored. A polyvalent primitive product operator and polyvalent returns are examined. Precedence rules are studied. Polyvalent low strand precedence works as follows:

4096

A A & times;A A+A
←4
Can an APL workspace be used as a data base?
Authors: Soop Karl
Published: January 2007

Experience from applications that use
APL
workspaces as data storage is reported. Different design decisions are discussed with illustrations of how
APL
is exploited. The final design, which achieves an utter simplicity of data representation, is described, with examples of usage. This simplicity allows a developer to concentrate on data manipulation, where the power of
APL
is at its best, rather than on storage techniques.
Teaching social studies concepts using concrete models expressed in APL
Authors: Traberman Tama
Published: January 2007

Concepts routinely used in middle and secondary social studies classes are often too abstract for students to comprehend. To fully understand the concept of nation, for example, students must first visualize and comprehend the notions of territory, boundaries, governments, cultures, history and shared goals and dreams for the future as well as other abstractions that may be subsumed in the word.

The problem becomes more complex when the teacher works with social studies concepts that are expressed numerically. When students work with familiar numbers in the tens and hundreds, they often have difficulty conceptualizing such ideas as population density and per capita income, which are expressed in terms or a single unit. When the numbers are in the billions or trillions, they are difficult to visualize and to comprehend. When the large numbers are used in social studies concepts such as gross national product, the problem compounds. Students may also lack skill in using mathematical functions involving these large numbers.

Teachers want students to understand rich and powerful ideas and they search for classroom activities to enhance student learning. Instructional techniques which provide students with concrete experiences and which allow for manipulation of the environment help students master such concepts. These strategies help students develop the ability to do abstract and formal thinking.

This paper focuses on concepts in global studies and presents some techniques for teaching these abstract ideas using computer models expressed in
APL.
Students manipulate these models in a variety of ways in class. Students learn to do research, store information and access and use data to comprehend their world more fully.
The engineering computer library (ENGLIB) an APL system for increased engineering productivity
Authors: Ward Harold R.
Published: January 2007

Choosing APL as the primary environment for engineering computer usage requires careful consideration of the extremes of computer usage sophistication, amounts of computation and storage, and types of computer programs. A system of APL workspaces is described which enables a small group of engineering technicians to provide appropriate computing support to a large group of users in and outside the Engineering Department.

ENGLIB is developed as a working model for a practical, conceptually simple environment for engineering data processing with facilities for handling and expediting all phases of engineering computer usage. Computer support ranging from routine job production to highly technical engineering programming to computer education is accomplished using APL as the background for man-machine synergy and interpersonal communication. Featured are interfaces to non-APL software and data storage/retrieval systems and a general description of the major sub-systems and key peripheral functions which enable ENGLIB to fit and increase engineering productivity.
TPLAN a table driven planning system
Authors: Jaffe S. B.
Published: January 2007

A general broad based APL system has been developed for the storage, retrieval and analysis of financial planning or accounting type data. It is valuable for the class of problems arising from collecting, organizing and consolidating data according to set formulas or recipes. The system, called TPLAN for
T
able driven
PLAN
ning system, has as its foundation three principal tables: a table of line or account names; a table of formulas specifying how each account is to be calculated; and a table of data with one row for each account. TPLAN is an “Open” system that provides the user with a collection of conformable utility functions which operate on the principal tables. The package consists of 52 APL functions which contain an average of 3-4 lines of code.
Generalizing APL I/O
Authors: Skutt Cory F.
Published: January 2007

Various APL systems have facilities that allow specialized I/O operations with a terminal. A new general approach is to use the system variable terminal types (@@@@
TT
) to designate I/O devices, modes, and options. The APL I/O supervisor for APL/V80 embodies this approach. This paper discusses the application goals, design objectives, challenges, and design of such a supervisor.
Valence and precedence in APL extensions
Authors: Benkard J. Philip
Published: January 2007

Extended operator syntax, defined operators, and strand notation are evaluated as APL extensions using the concept of syntactic binding, which is equivalent to the function scope rule and is more readily extended to other classes of objects. Changing syntax has wider impact than adding function, and its side effects should be considered before adoption.
Merrily we roll along
Authors: Shallit J. O.
Published: January 2007

We present an efficient method for determining the number of invocations of? given the value of (@@@@)
RL
, and solving the inverse problem. A full implementation is given for the random-number generator in
APL
\360 and its descendants.
Extending APL for pattern matching
Authors: Brenner Norman
Published: January 2007

APL includes a few primitives to permit searching of strings for single characters, principally the dyadic iota. APL2 adds iota underline. This latter function will find all occurrences of a given string in a longer string. Sometimes, however, more elaborate searching is needed; for example, searching for strings of variable length, searching for any of several alternate strings and avoiding of particular strings. In this paper, we describe two APL functions which permit very general string searching and substitution. Patterns describing the search to be done are written in APL with extended syntax. They are converted into a mixture of standard APL and defined functions and executed. The facility described is in experimental use as part of a macro language for the experimental full-screen editor ED3 [1].
Function and context
Authors: Taylor Stephen
Published: January 2007

This paper tackles three areas of difficulty in APL. The first is the subjection to APL syntax of the work presently performed by system commands under user intervention. The second is the growing diversity of object types noted by Crick. The third arises from the matter of assigning functions raised by Iverson and Wooster. All three areas are addressed by proposed extensions to the definition and concept of functions. The extended definition is shown to incorporate workspaces, groups, workspace libraries, file subsystems and namespaces as special cases, and to make certain system commands redundant.
Extending APL
Authors: Bozinovic Dragan
Published: January 2007

This paper explores certain underdeveloped parts of APL which ought to grow if APL is to qualify as implementation language for large and maintainable software systems. Following specific problems are discussed:

* Integrating APL with other parts of information processing environment.

• Operating systems.

• Programs written in other languages.

• Data bases.

* Using independently developed functions and subsystems.

• Problems with names.

• Problems with space.

* Execution control of object attributes.

* Communications among functions.

• Passing parameters.

• Returning values.

• Transferring control.

* Information hiding modules.

• Packaging related functions.

• Packaging data with functions.

• Local functions.
Uses of APL in a manufacturing environment
Authors: Gutzman Howard W. , Kellerman Edwardo
Published: January 2007

This paper describes the use of APL as a node of a high speed communications network. APL is used by the engineering community for statistical data analysis and for the creation of reports. These results are used to keep management informed of manufacturing status and to improve process control.
Experimental mathematics using APL and graphics
Authors: Haspel Charles , Vasquez Alphonse
Published: January 2007

Mathematics is ordinarily done by examining computations to extract likely conjectures. Only later are the conjectures proved, and, in traditional practice, the computations and motivations suppressed. We describe a computational investigation of the geometry of fundamental domains and units in totally real algebraic number fields. Our approach requires the finding of convex hulls in three dimensional space and their display and manipulation. APL and graphics are used for this purpose and appear to be essential for any practical pursuit of this approach.

This paper presents a definition of the problem, an example solution including drawings and portions of the APL code, and a sample of the results so far obtained. In addition, lessons learned from our own mistakes and fumblings are drawn to help and encourage other experimental mathematics explorations.
APL full screen editing and error handling
Authors: Hooker Raymond C.
Published: January 2007

This paper describes the development theory and program dynamics of a full screen APL schedule editor. The form of our editor is similar to the full screen editor available under IBM's SPF facility under TSO. Program function keys control paging and save/no save exits, and an insert column allows the addition and deletion of schedule items. This editor is protocol intensive, and its uniqueness lies in the error processing routines which consider complex inter field relationships both within lines and between lines. This paper attempts to present an overall approach to full screen protocol intensive error handling and reviews the history of APL full screen applications with a special regard to error handling techniques.
APL in education
Authors: Iverson Kenneth E.
Published: January 2007

Although the initial development of APL was motivated by the need for a precise notation for use ' ... in teaching classes, and in writing ... ', the use of APL as a teaching tool was lagged far behind its commercial use. This paper will review the current state of APL in education, and discuss possible strategies for advancing it.
The use and disuse of APL
Authors: Kanner Raymond
Published: January 2007

A sample of over 200 workspaces containing over 80,000 lines of code were analyzed to determine their composition and structure. Statistics were gathered on the frequency of all monadic and dyadic functions, operators, system variables and functions as well as other workspace and defined function characteristics. The results of the study indicated that only a fraction of the APL primitive function set was being utilized despite the language's richness. The ubiquitous 80-20 phenomenon was well represented. In general, 80% of all APL usage occurred with 20% of the available function set. This seems to support a contention that more awareness needs to be directed toward “thinking primitive” instead of only “thinking array”. Some comparisons with a previous study by Saal and Weiss will be made.
CPS - an APL conference planning system on a microcomputer
Authors: Richter Lutz , Ciorga Hellfried
Published: January 2007

The conference planning system CPS has been originally developed to facilitate the task of the program chairman in preparing a large international scientific conference. Finally it came out that this CPS system has a couple of quite general characteristics which makes it applicable as an instrument for similar planning purposes. This paper describes first the general duties during the planning phase and the final set-up of the scientific program of a large international conference. It further enlightens the logical structure of the system and explains a few of the implementational details. Finally some remarks are made concerning the experience in using this system and additional conclusions for further applications are drawn.
Eigenanalysis and polynomial root finding primitive functions
Authors: Schmidt S. , Brown J. A. , Jenkins M. A.
Published: January 2007

Working in conjunction with complex arithmetic extensions to APL, two new experimental primitive functions have been defined. They are an eigenanalysis primitive function and one for polynomial root finding. This paper traces our procedures of defining and testing the new functions, as well as an outline of the algorithms themselves. A few sample problems are given.
Interactive multilevel definition of APL functions
Authors: Sniedovich Moshe
Published: January 2007

An attempt is made to establish a convention that will make possible an interactive multilevel definition of APL functions. In accordance with this convention, functions can be defined at two levels: First an outline (flow-chart) is specified, this being followed by a detailed specification of the outline, prompted by the APL system. The convention is based on Iverson's direct definition form and enables the user to define long functions in an interactive manner. Preliminary experience with this convention indicates that it can improve the readability of APL functions
An APL-guided tour through the elements of multi-dimensional geometry
Authors: Thomson Norman D.
Published: January 2007

APL provides a powerful and succinct way of describing geometric elements in spaces of multiple dimensions. This paper gives notes on how simplexes, cross polytopes and measure polytopes can be modelled in a manner which enables them to be drawn on graphics terminals, which thus become valuable tools for geometrical insight.
The impact of microcomputers on APL
Authors: Van Cleave Philip A.
Published: January 2007

The advent of the Motorola 68000, a 16/32 bit microcomputer, now makes it possible to have a full-featured APL system and not have to sacrifice speed or the multi-megabyte workspace that you have become accustomed to (or, more likely, fantasized about) on your timesharing mainframe. This paper will discuss how the Motorola 68000, and the coming generation of 32-bit microcomputers will affect APL's direction and future, as well as open a vista of applications that previously could not be done in a practical manner using APL. The Computer Company's APL.68000 will be our case in point. The term “mainframe” when used in this paper will refer to both large IBM 370 class computers as well as minicomputers (HP 3000, DEC 2020, etc.).
A short-run forecasting model
Authors: Zilahi-Szabó Miklós G.
Published: January 2007

The paper is divided into four sections. The first section describes and introduces the dynamic problems that are involved in the interaction of short-run investment, financing and operating decision with forecasting and managing cash flows. The architecture of the system is described in the second and third sections. The system adopts a forecasting model and a relational database and support the language APL. The model integrates different statements to simulate “what if” and provides a tool for analysing the components of cash inflows and cash outflows over twelf time periods. The database model uses the language APL for defining, storing, accessing and modifying of data of the enterprises. The first experiences are given in the fourth section with an example of application.
Text-editing and photocomposing APL publications
Authors: Azzarello Arlene E.
Published: January 2007

Producing APL publications in a readable, pleasing, printed format is a challenging and time-consuming task. In an effort to get away from publishing APL documentation reproduced from typewriter terminal or line-printed output, I. P. Sharp Associates experimented with an interface between an APL text editor and a commercial photocomposing typesetter. Producing the
Sharp APL Reference Manual
[1] revealed some fundamental design issues which must be considered when constructing text editors and photocomposing interfaces. This paper deals with the text-editing effort behind the
Sharp APL Reference Manual
, the techniques employed, the problems encountered with the text editor and with the photocomposing interface, as well as the typographical and formatting conventions used in the first edition. The paper concludes with a discussion of design requirements for text editors and photocomposing interfaces.
The APL identity crisis
Authors: Brown J. A. , Jenkins M. A.
Published: January 2007

When a non empty result is produced in the application of reduction to an empty array, the result is filled with the identity element of the function of reduction. This paper explores the fill elements to be used when the function of reduction is not a scalar function.
QMOD
Authors: Groner Leo H.
Published: January 2007

An analytical queueing model generator (QMOD) is a package for generating and analyzing queueing networks. A description of a queueing network, written in a language meaningful to the user, is compiled into a set of matrices that characterize an analytical model of the network. Network flow rates are computed and used to derive arrival rates at each operation and tool. Tool arrival rates, service rates, and quantities are used in an analytic queueing model of the M/M/K form. Analytical models typically require orders of magnitude less computation time than do simulation models. They, therefore, lend themselves to parametric studies and optimization in ways that would be impractical with simulation models.
AP19 - a shared variable terminal I/O interface for APL systems
Authors: Hartigan Bruce J.
Published: January 2007

AP19 is an auxiliary processor which provides access, through the medium of shared variables, to the terminal input/output processor of an APL system. It allows the user to bring the power of APL to bear upon the management of subordinate and deferred sessions. This paper presents an overview of the design and development of AP19, describes its characteristics from a user's point of view, and gives some examples of how it has been used.

Insofar as AP19 is a component of an IBM internal version of APLSV, it is not available to customers. This paper does not constitute a commitment by IBM to provide such a facility, nor is it to be construed as an indication of future product direction.
Generic functions by nonstandard name scoping in APL
Authors: Kajiya James T.
Published: January 2007

We show how to acheive generic functions as in abstract datatypes (such as the Simula CLASS construct or ADA Package notion) for typeless languages, specifically APL. We do this by altering the standard dynamic scoping of names in APL to a scheme we call downward scoping.
Principal values and branch cuts in complex APL
Authors: Penfield Paul
Published: January 2007

Complex numbers are useful in science and engineering and, through analogy to the complex plane, in two-dimensional graphics, such as those for integrated-circuit layouts. The extension of APL to complex numbers requires many decisions. Almost all have been discussed in detail in a recent series of papers. One topic requiring further discussion is the choice of branch cuts and principal values for the primitive APL functions that require them. Conventional mathematical notation and the experience of other computer languages are of only moderate help. For example, one cannot find in the mathematics or computer-science literature a definitive value for the principal value of the arcsin of 3. The extension of APL to the complex domain presents a unique opportunity to define a set of choices that will best serve APL and other languages. This paper recommends locations of all branch cuts, directions of continuity of the branch cuts, and values at the branch points. It also recommends that comparison tolerance be used in the selection of principal values. The results apply to APL, other languages, applications packages, and VLSI hardware for complex calculations.
Expert systems—a technology for intelligent assistance
Authors: Reinstein Harry C.
Published: January 2007

Researchers in artificial intelligence have developed several systems capable of providing an expert level of assistance in solving complex problems. Areas addressed have included medical diagnosis and therapy, determination of molecular structure, design of experiments in molecular genetics, and application definition. These systems are generating interest in both the industrial and academic communities, and widespread development is beginning to emerge.

Expert systems share a common architecture and this presentation will describe this architecture and contrast it with classical problem solving techniques. Several examples of these systems will be discussed, including a new expert system developed at the IBM Scientific Center in Palo Alto. While most expert systems have been programmed in LISP, this one was built using APL, and the experience has illuminated both strengths and weaknesses of APL as a language for this area of artificial intelligence.
Generating design proposals with APL graphic functions
Authors: Wade John W.
Published: January 2007

This paper describes a computer graphics system intended for use by architectural designers in creating building form. It emphasizes ease of input by an organized system of unit sized geometric figures and provides a wide choice of modifications to those figures. The focus of the paper is on the method of unit figure construction that permits modifications to the figures, and interpolations between pairs of figures.
Compile time syntax analysis of APL programs
Authors: Weiss Zvi , Saal Harry J.
Published: January 2007

We present a technique for the compile-time determination of the syntactic attribute of names essential for the development of a compile-time parser for APL. The method is applicable to a large class of APL programs namely, programs which do not utilize certain features of the language allowing dynamic changes in the syntactic meaning of program statements. Empirical evidence supports the hypothesis that the restricted APL language encompasses almost all existing APL code.
Progress on an ANSI standard for APL
Authors: Wiedmann Clark
Published: January 2007

This paper discusses what a programming language standard is and discusses how one is developed. It also reports the progress to date on the planned ANSI standard for APL. Through the process of standardization, many existing differences between APL systems will be resolved, resulting in a benefit to the APL community that will fully justify the effort.