bluuebunny/crossref_metadata_2025 huggingface dataset:
Gerome Miklau speaks out on his SIGMOD distinguished dissertation award, how great it is to be a professor, and more
Authors: Winslett Marianne
Published: April 2007

I would like to take a moment to thank the many people who have helped me devise interview questions over the years. Often people propose questions under a promise of anonymity, so I will not name the individuals who have suggested questions---but you know who you are! Without you, these columns would not be possible. Thank you for your many excellent suggestions over the years.
The need for preservation aware storage
Authors: Factor Michael , Naor Dalit , Rabinovici-Cohen Simona , Ramati Leeat , Reshef Petra , Satran Julian
Published: April 2007

Digital Preservation
deals with ensuring that digital data stored today can be read
and interpreted
tens or hundreds of years from now. At the heart of any solution to the preservation problem lies a storage component. This paper characterizes the requirements for such a component, defines its desirable properties and presents the need for preservation-aware storage systems. Our research is conducted as part of
CASPAR
, a new European Union (EU) integrated project on the preservation of data for very long periods of time. The position presented was developed while designing the storage foundation for the CASPAR software framework.
Performance-directed energy management using
BOS
Authors: Ramamurthy Pratap , Palaniappan Ramanathan
Published: April 2007

One of the major challenges in today's computing world is energy management in portable devices and servers. Power management is essential to increase battery life. High end server systems use large clusters of machines that consume enormous amount of power. Past research has devised both software and hardware techniques to memory energy management but has overlooked the performance of applications in such environments. The result is that some of these techniques slowed down an application by 835%. In this paper, we look at software techniques for memory energy management without compromising on performance. The paper conceives of a new approach called
BOS - Ballooning in the OS
inspired from the VMware ESX server. The BOS approach consists of a kernel daemon which continuously monitors the accesses to memory chips and disk I/O. Based on the profiled information, the BOS daemon decides about powering down/up chips. Powering down is emulated within the kernel using mechanisms such as page migration and invisible buddy. Results indicate that chips with more allocated pages may not always be the most frequently accessed ones. A study has been done analyzing the effect of decreased memory size on disk activity and based on the study, a threshold based policy is proposed which is found to settle in the operating point for a simple applicaton. A single page migration incurs a cost of approximately 13μs and is one of the bottlenecks in the BOS approach.
Formal specification of program slicing
Authors: Wu Fangjun
Published: April 2007

Program slicing is a well-known technique that has been used in a variety of software engineering areas, such as comprehension, understanding, maintenance, debugging, testing, reuse, metrics, etc. This paper discusses how the formal specification language Z schema calculus may be used to specify program slicing. General aspects of program slicing are considered, i.e. dependence graphs and program slicing algorithms. This formalization could help in the correct understanding of program slicing and also the correct application of a desired slicing regime in a rigorous way.
TRICK
Authors: Mannarswamy Sandya , Doval Shruti , Sandanagobalane Hariharan , Nanjundaiah Mahesha
Published: April 2007

Compilers, during compilation, analyze the application being compiled and build up extensive knowledge about the program. This knowledge is essential for the compiler to produce correct object code. Though some part of this knowledge is retained in the generated object files as symbol table information to be used by the linker and/or debugger, most of it is discarded after the compilation is done. In this paper, we introduce the TRICK framework, which is an attempt to retain and reuse this internal information generated by the compiler as part of its program analysis, in building new tools or enhancing existing tools as well for reuse by the compiler for continuous program optimization. We present examples of how development and maintenance of various program analysis tools can be simplified by using the TRICK framework describing tools developed by our group as well as how TRICK framework can be employed in continuous program optimization by the compiler. TRICK framework can be part of both static and dynamic compilation system, though our current usage model is in the context of a static compilation system,
Design and implementation of a GUI for the TLC model checker
Authors: Wang B. , Pronk C.
Published: April 2007

For some time now, the TLC model checker [1] has been accepted as a very useful tool for checking specifications written in the language TLA+ [1]. The model checker helps the system designer to find errors in a specification before starting on an implementation. One facility that TLA+/TLC lacks however, is a GUI providing the user with more operational comfort. This article presents our design and implementation of a GUI for the TLA+/TLC-system, called the GTLA system. GTLA provides the user with three main facilities: a system editor, a simulator and a verifier (the TLC model checker) operable through a GUI. This article also discusses the tools which have been used for constructing the GTLA system.
News 2.0
Authors: Stanik John
Published: April 2007

Googlebombs Away
Decentralizing SIP
Authors: Bryan David A. , Lowekamp Bruce B.
Published: April 2007

SIP (Session Initiation Protocol) is the most popular protocol for VoIP in use today.1 It is widely used by enterprises, consumers, and even carriers in the core of their networks. Since SIP is designed for establishing media sessions of any kind, it is also used for a variety of multimedia applications beyond VoIP, including IPTV, videoconferencing, and even collaborative video gaming.
Unified Communications with SIP
Authors: Steinmann Martin J.
Published: April 2007

Communications systems based on the SIP (Session Initiation Protocol) standard have come a long way over the past several years. SIP is now largely complete and covers even advanced telephony and multimedia features and feature interactions. Interoperability between solutions from different vendors is repeatedly demonstrated at events such as the SIPit (interoperability test) meetings organized by the SIP Forum, and several manufacturers have proven that proprietary extensions to the standard are no longer driven by technical needs but rather by commercial considerations.
Proposal to dissolve SIGAPL
Authors: CACM Staff
Published: April 2007

The SGB EC brought forward a motion to dissolve SIGAPL, the Special Interest Group on the APL and J Languages based on an insufficient level of activity. The SGB EC recommends that SIGAPL's resources be used to provide up to two years worth of membership in another SIG of their choice (one year for SIGAPL members who have paid only one year of dues). Furthermore, the SGB EC has recommended that the SIGAPL community could organize conferences or other activities under the auspices of a more general SIG such as SIGPLAN. In accordance with ACM Bylaw 6 Section 11, this motion will be considered only after ACM's membership has had 60 days of notice to respond. If one percent of all ACM members, or five percent of SIGAPL members challenge the proposal to dissolve SIGAPL, the consideration of the motion will be delayed six additional months to give those challengers an opportunity to revitalize the SIG. ACM members who wish to challenge the proposed dissolution should contact Donna Cappo, Director of SIG Services, at cappo@acm.org, no later than June 15, 2007. Challenges must include your ACM membership number and should indicate whether you are a current member of SIGAPL. Other questions can be addressed to SGB Chair Joseph Konstan (konstan@acm.org).
Managing risk in offshore systems development
Authors: Sakthivel S.
Published: April 2007

The benefit of low-cost labor must be weighed against the risk of missed deadlines, dissatisfied users, and failure to reduce development costs.
Does telecommuting improve productivity?
Authors: Butler E. Sonny , Aasheim Cheryl , Williams Susan
Published: April 2007

Seeking solid evidence of demonstrable productivity gains.
Models and algorithms for deadlock in computer systems
Authors: Holt Richard C.
Published: April 2007

A major problem in multiprogramming systems in which processes may wait for resources is the prevention or detection of deadlocks. Deadlock is the situation in which one or more processes are blocked forever waiting for resources which can never become available. This problem has received considerable attention recently (see for example [1, 3, 4, 5, 6, 8, 9].) This note introduces a conceptually simple graph model; this model unifies much of the previous work on deadlock, leads to fast deadlock detection and prevention algorithms, and is suitable for teaching purposes.
Adding definition to active probing
Authors: Machiraju Sridhar , Veitch Darryl , Baccelli François , Bolot Jean C.
Published: April 2007

Active probing techniques have overwhelmingly been based on a few key heuristics. To progress to the next level a more powerful approach is needed, which is capable of filtering noise effectively, designing (and defining) optimal probing strategies, and understanding fundamental limitations. We provide a probabilistic, queueing-theoretic treatment that contributes to this program in the single hop case. We provide an exact inversion method for cross traffic distributions, rigorous system identifiability results to help determine what active probing can and can't achieve, a new approach for treating queueing theoretic 'noise' based on conditioning, and cross traffic estimators with enhanced properties
You must be joking... warns you
Authors: Faloutsos Michalis
Published: April 2007

I would like to apologise to both of my fans (which I will call Tom and Jerry respecting their request for anonymity for obvious reasons) for missing my column in the last issue. Their response was extremely flattering although the points of "silence is gold" and "measure twice, speak once, fool you thrice" kept appearing in their emails.
The state of peer-to-peer simulators and simulations
Authors: Naicken S. , Livingston B. , Basu A. , Rodhetbhai S. , Wakeman I. , Chalmers D.
Published: April 2007

In this paper, we discuss the current situation with respect to simulation usage in P2P research, testing the available P2P simulators against a proposed set of requirements, and surveying over 280 papers to discover what simulators are already being used. We found that no simulator currently meets all our requirements, and that simulation results are generally reported in the literature in a fashion that precludes any reproduction of results. We hope that this paper will give rise to further discussion and knowledge sharing among those of the P2P and network simulation research communities, so that a simulator that meets the needs of rigorous P2P research can be developed
Requirements development as a modeling activity
Authors: Diev Sergey
Published: April 2007

Considering requirements development as a modeling activity, this paper outlines our view of what a requirements model is. It then introduces some techniques useful in requirements development: concept-based requirements and requirements molecules.
Evaluation and comparison of cognitive complexity measure
Authors: Misra Sanjay , Misra A. K.
Published: April 2007

Weyuker properties have been suggested as a guiding tool in identification of a good and comprehensive complexity measure. In this paper, an attempt has been made to compare cognitive complexity measure in terms of nine Weyuker's properties with other complexity measures, such as McCabe's, Halstead's and Oviedo's complexity measures. Our intension is to study what kinds of new information about the measures are able to give.
Applying domain engineering using RAISE into a particular banking domain
Authors: Nami Mohammad Reza , Tehrani Mehdi Sagheb , Sharifi Mohsen
Published: April 2007

Recently, several flavors of formal methods have been gaining industrial acceptance and production quality software tools have begun emerging. Domain Engineering (DE) has been introduced as one of outstanding ideas in software development. It serves Formal Methods (FMs) that provide a rigorous, mathematical based framework for specifying, defining, and verifying systems in the software development for critical systems. New software engineering includes three phases consisting of domain engineering, requirement engineering, and design and implementation. The purpose of this paper is to introduce the key concepts of domain engineering with providing overview information about formal methods and applying RAISE as a formal method that has been used successfully on various, diverse applications. Then, a particular banking domain is specified with using them. Formal model presented in this paper is provable to implement this domain. With merginging object oriented technology with domain engineering, this model can be extended for serving in distributed systems. It improves reusability and reliability in such environments.
Estimating software complexity from UML models
Authors: Podgorelec Vili , Heričko Marjan
Published: April 2007

The possibility of predicting complexity of a software system in the design phase would be of an immense benefit for estimating complexity and with it associated effort of the implemented system. In this paper we cogitate on estimating complexity of a software system based on the UML models of the system. We test whether there is a valid relation between the complexities of an implemented software system and its UML model; and how this relation can be appropriately used. The measuring is performed with the fractal complexity measure a, which is based on long-range power law correlations.
Podcasts about software engineering
Authors: Rech Jörg
Published: April 2007

Podcasts are a new form of information source that enables every-one to listen to information stored in audio files -- similar to audio books -- on the internet. Podcasts are a valuable tool to spread in-formation in acoustic form especially such as interviews with experts from industry, features about new technologies, or news from conferences. Similar to radio these contributions are stored on the internet and can be downloaded by anyone, anytime, and anywhere. This paper presents several podcasts for software engineering and the technology behind Podcasting.
Visual support of software engineers during development and maintenance
Authors: Rech Jörg , Schäfer Waldemar
Published: April 2007

Software systems have reached a level of complexity that puts them beyond our ability to evolve and maintain them easily. This increases the need for soft-ware organizations to develop new or rework existing systems with high quality. CodeSonar was developed to support software engineers during software development and maintenance activities through the visualization of source code and quality defects using a visual interface in the eclipse IDE. A first qualitative evaluation indicates that it helps the user in navigating in the software system.
A looming fault tolerance software crisis?
Authors: Romanovsky Alexander
Published: April 2007

Experience suggests that it is edifying to talk about software crises at NATO workshops. It is argued in this position paper that proper engineering of fault tolerance software has not been getting the attention it deserves. The paper outlines the difficulties in building fault tolerant systems and describes the challenges software fault tolerance is facing. The solution being advocated is to place a special emphasis on fault tolerance software engineering which would provide a set of methods, techniques, models and tools that would exactly fit application domains, fault assumptions and system requirements and support disciplined and rigorous fault tolerance throughout all phases of the life cycle. The paper finishes with an outline of some directions of work requiring special focused efforts from the R&D community.
Introduction
Authors: Savvides Andreas , Martin Richard
Published: April 2007

The field of localization concerns the positioning of devices in physical space. The ability to cheaply and effectively locate mobile devices will allow users to understand the when, where and what of the physical world. Access to a wireless device's location would offer new application opportunities in diverse areas such as environmental monitoring, security, agriculture, emergency response, health care, and ubiquitous computing.
Probabilistic region-based localization for wireless networks
Authors: Wang Feng , Qiu Lili , Lam Simon S.
Published: April 2007

Determining the physical location of wireless nodes is important to a wide variety of applications. In this paper, we propose a series of probabilistic region-based localization algorithms, including using static grids, segments of grids, and dynamic meshes. These algorithms provide a wide range of trade-off between accuracy and cost, making them suitable for different types of networks, such as sensor networks and mesh networks. Furthermore, we propose several techniques to extract and leverage additional information on location constraints, which is shown to significantly improve the localization accuracy and can be applied to other localization schemes. Finally we develop techniques to enhance robustness of localization, and show that the enhanced scheme can achieve high accuracy even in the presence of significant measurement errors.
Using public domain multiprecision arithmetic packages for computer security software applications on a personal computer
Authors: Russell Selwyn
Published: April 2007

Implementation of modern cryptography needs both normal and modular arithmetic using numbers with hundreds of digits. This is often a discouragement to the use of such methods, even though a number of public domain packages are available. This paper shows how available multiprecision packages can easily be used to incorporate arbitrarily high security into computer systems. Examples using the readily available Lenstra package for the RSA and El Gamal cryptosystems are given.
Book review: Using Drawperfect by Stuart Bloom (Lloyd Short, 1991)
Authors: Wiseman Paul
Published: April 2007

Using Drawperfect is a well written book that covers the basics of Drawperfect to more advanced topics, making it a good book to grow with. The first several chapters cover simple commands and familiarize the reader with the different tools Drawperfect has to offer as well as explain what hardware is required and how to install the software. For an experienced Wordperfect user, many of Drawperfect's pull-down menus and set-up options will seem familiar, but this book does a good job of explaining how to get around in Drawperfect without going overboard. There are several illustrations of various menu screens and drawings that make it easy to follow along with the instructions without getting lost or confused. The author also precedes each chapter with a brief summary of the material covered which is useful because it saves on time hunting for information about a particular command.
Book review: Unix Applications Programming - Mastering the Shell by Ray Swartz (Sams & Co., 1990)
Authors: Osofsky David
Published: April 2007

The book is approximately 400 pages in length exclusive of the appendix. The appendix consists of a set of Bourne Shell quick reference tables, a set of regular expression quick reference tables, a bibliography, and answers to exercises that are introduced in many of the chapters.
Porting AIX onto the Student Electronic Notebook
Authors: Ioannidis John , Maguire Gerald Q. , Ben-Shaul Israel , Levedopoulos Marios , Liu Micky
Published: April 2007

We describe the Student Electronic Notebook and the process of porting IBM's AIX 1.1 to run on it. We believe that portable workstation-class machines connected by wireless networks and dependent on a computational and informational infrastructure raise a number of important issues in operating systems and distributed computation (e.g., the partitioning of tasks between workstations and infrastructure), and therefore the development of such machines and their software is important. We conclude by summarizing our activites, itemizing the lessons we learned and identifying the key criteria for the design of the successor machines.
Mass market computer for software development
Authors: Gentleman W. Morven , Wein Marceli
Published: April 2007

The mass market or appliance computer has become a plausible alternative to workstations for software development. While it is easy to use for software development, a different style of development emerges. By being truly personal, the mass market computer provides a focus for all the professional activities of a developer. The primary form of software used on such computers is shrink-wrapped software; this has profound implications on how the software is used and the make-or-buy trade-off takes on an entirely new meaning. This paper describes the advantages of mass market computers. As an example, the paper presents how an environment, consisting of a network of mass market computers, has influenced the development of a novel source management scheme.
Automated test plan generator for database applications systems
Authors: Robbert Maryann , Maryanski Fred J.
Published: April 2007

As database applications become larger and more complex, the development of suitable test plans to assure robust and reliable software becomes essential. The testing procedure must establish the applications reliability from the human expectation viewpoint as well as its correctness and robustness.The predetermined goals of this testing procedure are to assure high reliability of the application and ascertain that the software performed according to specifications, while remaining within the project's time and budgetary constraints. Errors identified during development can be corrected with minimal cost when compared to errors uncovered by users after the software release. By overlapping testing with development, and automating the production of a standardized set of test plans, the incremental production time can be minimized. By generating an application specific test plan, syntactic and semantic specifications of the actual system applications can be tested. A side effect of this specific, interleaved correctness testing is the uncovering of user interface inconsistencies and their refinement before exposure of the application to the real end user.Analysis of the results of our experimental testing showed the keystone to be the test plan. Since the completeness and veracity of this document is a prime determining factor in the validity of the testing, we have developed program using C++ on a Sun workstation to automatically generate test plans from the design schema.This paper presents an automated/manual testing scheme suitable for assuring the validity of large database applications. The initial premises, design execution and consequences of the test procedure is detailed followed by a description of the automation of strategic components.
MGNet
Authors: Douglas Craig C.
Published: April 2007

MGNet provides a mechanism for exchanging information and computer programs related to multigrid and/or domain decomposition methods.
Book review: Inside Autosketch (Ver. 3.0), 2nd Ed. by Frank Lenk (New Riders Publishing, 1990)
Authors: Daley Lawrence R.
Published: April 2007

"Inside Autosketch" is a supplementary how-to manual for the beginning user of the excellent program Autosketch by Autodesk, Inc.. The book would be as well suited for the experienced Autosketch user, as I have been for several years, and is a very good main manual covering all features of the software. It does so in a more complete and readable manner than the documentation supplied with the program.
A study of 80x86/80x87 floating-point execution
Authors: Miljanic Zoran , Kaeli David R.
Published: April 2007

The evolution of a processor architecture must include enhancements to both the fixed and floating-point units. To increase overall performance, architectural and implementation performance improvements to the floating-point unit must keep pace with the performance enhancements made to the fixed-point unit. In this paper we evaluate the performance enhancements provided by the evolution of the floating-point co-processor for the Intel 80x86 family. Using a suite of traces, we show how code compiled for predecessor co-processors will perform on current floating-point implementations.
Characteristics of files in NFS environments
Authors: Bennett J. Michael , Bauer Michael A. , Kinchlea David
Published: April 2007

As local area networks of workstations and file servers grow, the management of user and system files becomes increasingly more challenging for system administrators. In order to develop effective management tools for these administrators, the nature of files in workstation environments must be understood. This paper presents a static analysis of file usage patterns of a typical workstation environment using a standard client-server paradigm (NFS). The data reveals some differences in characteristics for files in networked environments compared with files in timesharing systems. The study also suggests what data and techniques might be appropriate as a basis for a management tool for network administrators. The paper concludes with a recommendation for the construction of a real-time management and data gathering tool that may give early-warnings of server overload or may be useful in exploring trade-offs among file allocation strategies.
Error in Unix commands
dc
and
bc
for multiple-precision-arithmetic
Authors: Dittmer Ingo
Published: April 2007

Erroroneous computations were found in the modulo-function % of the multiple-precision-software dc, standard in Unix™ -systems. Since the command bc is based upon dc, it is concerned, too.
A microcomputer implementation of an ER query and update interface
Authors: Czejdo Bogdan D.
Published: April 2007

Several query languages have been proposed in which users graphically manipulate Entity-Relationship (ER) diagrams to formulate queries. In this paper we present a method of implementing an ER query and update language as an interface for a relational Database Management System. The approach is based on interactive manipulation of ER database schemas and generation of SQL expressions for an underlying relational database. The graphical query and update formulation process is formally defined. We assume that the information reflecting the current state of the query and update formulation process is maintained in a formal model. The model described in other publications is significantly modified and extended. The information included in the extended model allows an ER diagram corresponding to the current state of the query to be displayed on the terminal screen. It is also used to generate an equivalent SQL expression for a relational database. The integrity constraints for the formal model are specified.
A pseudo-ODE modelling trick for the direct method of lines computation of important fracture mechanics parameters
Authors: Xanthis Leonidas S
Published: April 2007

A novel introduction in fracture mechanics of pseudo-ordinary differential equations (ODEs) corresponding to the stress intensity factors (SIFs), augments the under-determined system of ODEs produced by the method of lines (MOL) solution of the equations of elasticity, in the presence of cracks. With this modelling "trick", which is natural to MOL, the SIFs are obtained directly, as part of the solution unknowns, thus avoiding the uncertainties associated with other indirect methods.
An Ada package for multi-precision integer arithmetic
Authors: Knight D. G.
Published: April 2007

An Ada package (LINTPAC) which provides facilities to perform arithmetic with integers of any length is described. The package and a number of demonstration programs are available from the author.
The conjugate gradient method in the presence of clustered eigenvalues
Authors: Flores José D.
Published: April 2007

We present the conjugate gradient method, CG method, to solve large dense linear systems whose associated matrix has clustered eigenvalues, and we give the implementation of the algorithm using MATLAB, an interactive programming language for scientific computing.
The enable construct for exception handling in Fortran 90
Authors: IFIP Working Group 2.5 CORPORATE
Published: April 2007

It is apparent that a good mechanism for handling computing exceptions is essential for the construction of robust and maintainable Fortran 90 code. Ideally such code would execute rapidly when all is well and not fail in situations such as when data is near the arithmetic limits or there is insufficient memory for an automatic array. A language feature is needed that permits transfer of control when necessary from straightforward fast code to slower code that uses an alternative algorithm.
Variants of matrix-matrix multiplication for Fortran-90
Authors: Douglas Craig C. , Slishman Gordon
Published: April 2007

The Fortran-90 standard requires an intrinsic function
matmul
which multiplies two matrices together to produce a third as the result. However, the standard does not specify which algorithm to use. We consider an extension to the
matmul
syntax which allows a Winograd variant of Strassen's algorithm to be added. We discuss an implementation that is in a commercial Fortran-90 offering.
Interval rational = algebraic
Authors: Kreinovich Vladik
Published: April 2007

Rational functions can be defined as compositions of arithmetic operations (+, -,.,:). What class of functions will be get if we add to this list the "interval" operation (that transforms a function f of n variables and given intervals X
1
, ...., X
n
into the bounds for the range f(X
1
, ..., X
n
))? In this paper, we prove that adding this "interval" operation to rational functions leads exactly to the set of all (locally) algebraic functions.In other words, algebraic functions can be described as compositions of arithmetic operations and the "interval" operation.This result provides an additional explanation of why naive interval computations sometimes overshoot:• the desired dependency is (locally) a genera algebraic function;• naive interval methods results in a (locally) rational function;• not all algebraic functions are rational.
For unknown-but-bounded errors, interval estimates are often better than averaging
Authors: Walster G. William , Kreinovich Vladik
Published: April 2007

For many measuring devices, the only information that we have about them is their biggest possible error ε > 0. In other words, we know that the error Δ
x
=
x
-
x
(i.e., the difference between the measured value
x
and the actual values
x
) is random, that this error can sometimes become as big as ε or - ε, but we do not have any information about the probabilities of different values of error.Methods of statistics enable us to generate a better estimate for
x
by making several measurements

x
1
, ..., x
n
.

For example, if the average error is 0 (
E
(Δ
x
) = 0), then after
n
measurements, we can take an average
x
= (
x
1
+ ... +
x
n
)/
n
, and get an estimate whose standard deviation (and the corresponding confidence intervals) are √
n
times smaller.Another estimate comes from interval analysis: for every measurement
x
i
, we know that the actual value
x
belongs to an interval [
x
i
-ε,
x
i
+ε]. So,
x
belongs to the intersection of all these intervals. In one sense, this estimate is better than the one based on traditional engineering statistics (i.e., averaging): interval estimation is
guaranteed.
In this paper, we show that for many cases, this intersection is also better in the sense that it gives a more
accurate
estimate for
x
than averaging: namely, under certain reasonable conditions, the
error of this interval estimate decreases faster (as 1/n) than the error of the average (that only decreases as
1/ √n).A similar result is proved for a multi-dimensional case, when we measure several auxiliary quantities, and use the measurement results to estimate the value of the desired quantity
y
.
An example of error propagation reinterpreted as subtractive cancellation
Authors: Delaney James A.
Published: April 2007

The simple recursive algorithm I
k
= 1 - k I
k-1
with I
0
= 1 - 1/e (the result of an integration by parts) has served as an example of catastrophic error propagation. The traditional interpretation is that an initially small roundoff error in 1/e grows by a factor of k1. This note presents an alternate error analysis in terms of subtractive cancellation. From this perspective, the precise error is observable in detail, as is the effect of the floating point mantissa length. (Related material is referenced in 6.)
Why monotonicity in interval computations? A remark
Authors: Koshelev Misha , Kreinovich Vladik
Published: April 2007

Monotonicity of functions has been successfully used in many problems of interval computations. However, in the context of interval computations, monotonicity seems somewhat ad hoc. In this paper, we show that monotonicity can be reformulated in interval terms and is, therefore, a natural condition for interval mathematics.
Case studies of choosing a numerical differentiation method under uncertainty
Authors: Finkelstein Andrei M. , Koshelev Misha
Published: April 2007

In many real-life situations (including computer-aided design and radiotelescope network design), it is necessary to estimate the derivative of a function from approximate measurement results. Usually, there exist several (approximate) models that describe measurement errors; these models may have different numbers of parameters. If we use different models, we may get estimates of different accuracy. In the design stage, we often have little information about these models, so, it is necessary to choose a model based only on the number of parameters
n
and on the number of measurements
N.
In mathematical terms, we want to estimate how having
N
equations Σ
j
c
ij
a
j
=

y
i

with
n
(
n < N
) unknowns

a
j

influences the accuracy of the result (

c
ij

are known coefficients, and

y
i

are known with a standard deviation σ[
y
]). For that, we assume that the coefficients

c
ij

are independent random variables with 0 average and standard deviation 1 (this assumption is in good accordance with real-life situations). Then, we can use computer simulations to find the standard deviation σ' of the resulting error distribution for

a
i
.

For large
n
, this distribution is close to Gaussian (see, e.g., [21], pp. 2.17, 6.5, 9.8, and reference therein), so, we can safely assume that the actual errors are within the 3σ' limit.
Making hard constraints soft
Authors: Krogh Fred T
Published: April 2007

Search algorithms solve a problem by evaluating a user defined function at a sequence of points that tend to converge to the desired solution. If the function contains an expression such as (cos x - e
y
sin z)
1/2
which can not be evaluated at some points, the search algorithm may fail at some intermediate point. Faced with such a problem one is inclined to think of using an algorithm that allows one to impose constraints. (For this example, cos x - e
y
sin z ≥ 0.) But unlike most constraints that are imposed, we need to impose the condition that no attempt be made to evaluate the function (or perhaps another constraint) when the constraint is not satisfied. I call such a constraint a "hard" constraint.
2
New standards for educational technology relevant to multiple ACM SIGs
Authors: Rada Roy , Schoening James
Published: April 2007

Standards are relevant to every ACM SIG. The new JavaScript standardization effort from the European Computer Manufacturers Association would be particularly relevant to SIG Software Engineering. Managing Multimedia information Structures from the European Workshop for Open Systems would be particularly relevant to SIG Multimedia. The new ISO 14000 standards for environmental quality management systems might concern SIG Management Information Systems. One of the latest standardization efforts is for educational technology, and to our knowledge only one formal Standards Development Organization, namely the Institute of Electrical and Electronic Engineers (IEEE), is directly addressing educational technology standards.
An interactive program to approximate double integrals
Authors: Maerten Bart , Cools Ronald
Published: April 2007

Using
Cubpack++
to approximate a double integral requires from users that they write a small C++ program. Although example programs are provided, this still introduces a treshold. This short note describes an interface to
Cubpack++
that relieves users from any need to write C++.
Analytic derivation of comparisons in binary search
Authors: Rolfe Timothy J.
Published: April 2007

Numerous authors of programming texts and algorithms / data structures texts develop code for the binary search. The common implementation is one in which the loop contains two comparisons for three outcomes --- the key is to the left of the midpoint, to the right of the midpoint, or exactly at the midpoint --- Implementation A below.
Konrad Zuse
Authors: Giloi Wolfgang K.
Published: April 2007

Relatively little known outside of Germany, Konrad Zuse realized the first functioning computer in 1941 and also developed with his so-called Plankalkül in 1943-1945 the first high-level programming language, However, his inventions were overshadowed by World War II, and his work was overtaken in the public mind by the works of Aiken and von Neumann. This essay, a shortened and revised version of a eulogy by the author in December 1996 at the celebration of Zuse's 80th birthday at his former alma mater, the Technical University of Berlin, gives an overview of Zuse's work and puts his contributions in context.
Symbolic packages in the development of numerical algorithms
Authors: de Pillis John
Published: April 2007

Our research has the objective of finding quicker, more efficient numerical methods (computer algorithms) for solving large, sparse linear systems. Yet, in the development and discovery of new methods, we have been relying on auxiliary software packages.
Provably monotone approximations, II
Authors: Dunham Charles B.
Published: April 2007

In the preceding note (Dunham, 1987) were given forms of approximation that were provably monotone for suitable arithmetic, but left open the forms(1) c + x * r (x),where r could be a rational (the Kuki form on middle p. 9) or the next to last stage in Horner's method (top p. 10). If r is positive and non-decreasing on a positive interval I, (1) is obviously monotone on I for monotone arithmetic. This leaves two cases, (a)r positive and (slowly) decreasing on I, and (b) r negative on I. We consider them separately.
Another alternative for bordered systems
Authors: Knight William
Published: April 2007

This partitioned system, [EQUATION] is to be solved many times with the same n by n matrix,
A
, but differing n-vectors,
b
,
c
, and
f
, and differing scalars d and g. By using a bordering algorithm,
A
need be inverted once only. The remaining computation, done often, uses 2n
2
+3n+constant long operations (multiplications + divisions). Govaerts and Pryce (1987) consider the situation when
A
is nearly singular although (1) itself is well conditioned, reporting that using a bordering computation followed by iterative refinement of the initial poor solution works well, being both simple and practical.
The transition of numerical software
Authors: Smith Barry F.
Published: April 2007

Traditionally, much of the numerical analysis community has focused on issues of error bounds, convergence rates and time and space complexity of numerical algorithms, not on robust, reusable software implementations. Until recently, many of the computer science advances in software engineering rarely filtered into numerical codes.With the growing complexity of (1) parallel computers, (2) numerical algorithms, and (3) application physics that must be modeled, the community has finally begun to realize the need for new techniques to manage the complexity of the codes. Thus, the entire community has entered a learning curve; some groups are well advanced on the curve and develop and use sophisticated class libraries and frameworks, while others are still struggling with dynamic memory allocation and data structures.This article will discuss some of the issues involved in the transition from a Fortran 77 nuts-and-bolts approach to developing numerical code to a higher level, abstract, object-oriented methodology and how our PETSc development team is trying to ease that transition. In addition, it will discuss two limitations in the Fortran 90 syntax that make it difficult to take full advantage of abstraction when programming purely in Fortran 90.
Towards programming small computers for AYO game
Authors: Anumba Raphael O.
Published: April 2007

Machine Intelligence will soon be sought to play AYO, a Nigerian board game, and an equivalent to European Chess. In this paper, a design of an imperative Man-Machine interface, towards the development of an efficient and better strategic moves for the game is presented.Algorithm for moves, captures, end-of-game and in particular the strategy which makes use of matrix of difference-in-capture in two level abstraction, will be discussed.The algorithm which had been coded in various high level programming languages for different systems, is presently coded in BASIC to run on IBM-PC and HP series of micro-computers at the Bauchi campus of the Ahmadu Bello University.
A programmer's guide to the Edison language
Authors: Scott Terry A. , McBride R. A.
Published: April 2007

The Edison System is a software system written by Brinch Hansen. It was originally done for a PDP-11 computer, but is now available for the IBM PC and compatibles and consists of:• an operating system,• an operating system kernel,• editor,• Edison language compiler,• an assembler for the Alva assembly language,• a program for document formatting,• some miscellaneous utility programs.Except for the operating system kernel, which is written in Alva assembly language, all of these programs are written in the Edison language. Complete information on the Edison System and Edison Language for the PDP-11, which is nearly identical to the IBM PC system, can be found in the book,
Programming A Personal Computer
, by Per Brinch Hansen [BRI 1982].
Caching on a microcomputer, part 2
Authors: Wood Percy G.
Published: April 2007

The article in the previous issue presented the idea of a disk cache and outlined the programming necessary to use it for read accesses. This article continues with the relevant programming for write accesses, using some of the subroutines contained in the previous article, and continues with other implementation details. It picks up with the branch not taken there; that is, the I/O command is not a read.
Maximizing modem bandwidth
Authors: Baker W.
Published: April 2007

This paper arises out of an idea I had to optimize the bandwidth use on the connection whenever I dialed in to work from home. So often I wanted to be able to work interactively while downloading files, but couldn't. Unfortunately I have changed jobs since then, and so the design remains an idea, rather than a reality. I share it for your edification.
A computational algorithm for LU decomposition of a sequence of matrices that differ only in one or more elements
Authors: Zahir M. S.
Published: April 2007

A computational algorithm for an efficient LU decomposition of a sequence of matrices that differ in one or more elements is presented and some possible areas of engineering and business applications are outlined. CPU time, as measured in an implementation of the algorithm using FORTRAN code, is shown to agree very well with the estimated operations count.
Nonexercise movement in elderly compared with young people
Authors: Harris Ann M. , Lanningham-Foster Lorraine M. , McCrady Shelly K. , Levine James A.
Published: March 2007

The association between free-living daily activity and aging is unclear because nonexercise movement and its energetic equivalent, nonexercise activity thermogenesis, have not been exhaustively studied in the elderly. We wanted to address the hypothesis that free-living nonexercise movement is lower in older individuals compared with younger controls matched for lean body mass. Ten lean, healthy, sedentary elderly and 10 young subjects matched for lean body mass underwent measurements of nonexercise movement and body posture over 10 days using sensitive, validated technology. In addition, energy expenditure was assessed using doubly labeled water and indirect calorimetry. Total nonexercise movement (acceleration arbitrary units), standing time, and standing acceleration were significantly lower in the elderly subjects; this was specifically because the elderly walked less distance per day despite having a similar number of walking bouts per day compared with the young individuals. The energetic cost of basal metabolic rate, thermic effect of food, total daily energy expenditure, and nonexercise activity thermogenesis were not different between the elderly and young groups. Thus, the energetic cost of walking in the elderly may be greater than in the young. Lean, healthy elderly individuals may have a biological drive to be less active than the young.
Cardiac effects of endothelin receptor antagonism in endotoxemic pigs
Authors: Konrad D. , Haney M. , Johansson G. , Wanecek M. , Weitzberg E. , Oldner A.
Published: March 2007

Myocardial depression in sepsis is frequently encountered clinically and contributes to morbidity and mortality. Increased plasma levels of endothelin-1 (ET-1) have been described in septic shock, and previous reports have shown beneficial effects on cardiovascular performance and survival in septic models using ET receptor antagonists. The aim of the current study was to investigate specific cardiac effects of ET receptor antagonism in endotoxicosis. Sixteen domestic pigs were anesthetized and subjected to endotoxin for 5 h. Eight of these pigs were given tezosentan (dual ET receptor antagonist) after 3 h. Cardiac effects were evaluated using the left ventricular (LV) pressure-volume relationship. Endotoxin was not associated with any effects on parameters of LV contractile function [end-systolic elastance (Ees), preload recruitable stroke work (PRSW), powermax/end-diastolic volume (PWRmax/EDV) and dP/d tmax/end-diastolic volume (dP/d tmax/EDV)] but with impairments in isovolumic relaxation (time constant for pressure decay, tau) and mechanical efficiency. Tezosentan administration decreased Ees, PWRmax/EDV, and dP/d tmax/EDV, while improving tau and LV stiffness. Thus, dual ET receptor antagonism was associated with a decline in contractile function but, in contrast, improved diastolic function. Positive hemodynamic effects from ET receptor antagonism in acute endotoxemia may be due to changes in cardiac load and enhanced diastolic function rather than improved contractile function.