Nash - Scientific Computing with PCs

HomeScientific Computingwith PCsJohn C. NashFaculty of AdministrationUniversity of OttawaMary M. NashNash Information Services Inc.ISBN: 0 88769 008 4Copyright © 1984, 1993 J C Nash and M M NashThis book is available from several Internet servers by anonymous FTP. It is NOT freeto use, though the file SCPCDOC.PS contains the Preface, Contents and an examplechapter that you may freely print and use. If you decide to use the text of the book,there is a $10 / copy licence payable toNash Information Services Inc.1975 Bel-Air Drive, Ottawa, Ontario, K2C 0X1, CanadaFax: (613) 225 6553Email contacts: jcnash@aix1.uottawa.ca,mnash@nis.synapse.netThis file formatted on 29 November 1997iNextiiCopyright © 1984, 1994 J C & M M NashSCIENTIFIC COMPUTING WITH PCsNash Information Services Inc., 1975 Bel Air Drive, Ottawa, ON K2C 0X1 CanadaCopy for:Dr.

Dobb’s JournalPrefaceThis book tells "what to", "why to" and "when to" use personal computers (PCs) for carrying out scientificcomputing tasks. There are many books that purport to tell users how to operate particular softwarepackages or to set up and maintain their personal computer hardware. These "how to" volumes have theirproper role and utility. Our goal is different: we aim to present ideas about the management decisionsinvolved in using PCs for scientific and technical computing.The audience for this book is any scientist, engineer, statistician, economist, or similar worker who isconsidering using a personal computer for all or part of his or her technical work.

The ideas we presentcan be used at the individual or group level. Being ideas about the management of resources, they arekept simple to the extent that readers will think "I know that." We stress, however, that it is the day-to-daypractice of management ideas that counts; theoretical knowledge is like a smoke alarm without a battery.There are three themes to this book:•Deciding what is or is not reasonable to attempt in the way of scientific computing with a PC;•Learning about and finding software to carry out our tasks with a minimum of fuss;•Choosing the tools to match the task to keep costs low.By PC we will mean any computer system that is managed, used and maintained by a single person.

Thetypical examples are the relatives and descendants of the original IBM PC and the Apple Macintosh, butother machines and workstations have similar properties. Workstation networks and mainframes withsystem support staff have quite different management strategies. Portable computers used with such largersystems are, however, very likely to be used in a way that requires the user to exercise management skills.Our examples use mainly MS-DOS PCs since these are the most common.The reader will notice some repetition of ideas we feel important; we also have tried to keep sections ofthe book self-contained.The distribution mechanism for this book is an experiment in a new form of publishing using the Internet.We did not intend this to be the case.

Unfortunately the publisher who commissioned the book as aventure into a new subject area decided to retreat in the face of recessionary pressures after we hadsubmitted a typeset manuscript. Interest from other publishers did not transform itself into a contract. Ourresponse has been to pay to have the work professionally reviewed — as a good publisher should — andto then edit and produce the work in a form that users can print out for their own use.The current work has been formatted to reduce the number of pages from about 300 to about 200 bychoosing margins that use more of the page area on traditional letter-size paper.

We believe that A4 paperusers will find that pages fit this size also.Your comments are welcome.John & Mary Nash, Ottawa, September 19940: PREFACE AND CONTENTSiiiContentsPart I: Panorama4.8Chapter 1:4.94.104.114.124.131.11.21.3History and goalsNon-goalsThe scientific method and ouraudienceComputer configurations of interestComputing styles1.41.5Chapter 2:2.1Data processing capabilities ofPCsNon-mathematical data processingrelated to calculationCommunications — Access to remotedataAutomated data collectionInput, output, edit, and selectionScientific text processingMacro-editors and data convertersGraphicsReport writersProgramming and programdevelopmentAdministration of research2.22.32.42.52.62.72.82.92.10Chapter 3:3.13.23.33.43.5Introduction and Purpose — HowScientific Problems are SolvedComputational capabilities of PCsGood newsApplication problemsComponent computational problemsComponent symbolic problemsGetting things to workPart II: Computing environmentsChapter 4:4.14.24.34.44.54.64.74.8Will a PC suffice?HardwareSoftwareInterfacing, communications and datasharingPeripheralsOperational considerationsIssues to be addressedProgramming effectivelyThe software developmentenvironmentChapter 5:5.15.25.35.45.55.65.7Chapter 6:6.16.26.36.46.56.6Chapter 7:7.17.27.37.47.57.67.77.8Chapter 8:8.18.28.38.48.58.6Input/output problems — bugs andglitchesDebugging and trouble-shootingPrecision problemsSize problemsUtilities and supportSummaryFile managementFile creation and namingTypes and distributions of filesCataloguing and organizing filesBackupArchivingVersion controlLoss versus securityProgramming Aids and PracticesProgramming tools and environmentsCross-reference listing and datadictionaryFlowchart or other algorithmicdescriptionStructure and modularitySub-programs — data flowProgrammer practicesSize DifficultiesDetermining memory and datastorage limitsChoice or adjustment of datastructuresUsage mapRestructuringReprogrammingChainingChange of methodData storage mechanisms for specialmatricesTiming ConsiderationsProfile of a programSubstitution of key codeSpecial hardwareDisk access timesTime/accuracy and other trade-offdecisionsTiming toolsivCopyright © 1984, 1994 J C & M M NashSCIENTIFIC COMPUTING WITH PCsNash Information Services Inc., 1975 Bel Air Drive, Ottawa, ON K2C 0X1 CanadaChapter 9:9.19.29.39.49.59.69.79.8Chapter 10:10.110.210.310.410.510.610.7Chapter 11:11.111.211.311.411.511.611.711.8Part III:Chapter 12:12.112.212.312.412.512.612.712.812.9DebuggingUsing output wiselyBuilt-in debugging toolsListings and listing toolsSub-testsFull tests — robustness of code to badinputFull tests — sample and test dataResilience to I/O failure and diskproblemsTests of language translatorsUtilities — a desirable setEditorsFile view, move, copy, archive andbackupFile display, conversion and printFile comparisonDirectories and catalogsFixup programsSortingLooking after the Baby Hardware and Operating PracticeCleanliness and a decent physicalenvironmentBad habits — smoke, sticky fingers,childrenMagnetic disks and their careTapes, CDs and other storage mediaPower considerationsInterference and radio frequencyshieldingServicing and spare partsConfiguration maintenanceThe problem and its solutionmethodSteps in Problem SolvingProblem formulation exampleAlgorithm choiceAlgorithm implementation —programmingDocumentationTesting — data entryTesting — sub-programsTesting — complete programsProduction runsModifications and improvementsChapter 13:13.113.213.313.413.513.613.7Part IV:Chapter 14:14.114.214.314.414.514.6Chapter 15:15.115.215.315.415.515.6Chapter 16:16.116.216.316.416.516.6Chapter 17:17.117.217.317.417.517.6Copy for:Dr.

Dobb’s JournalProblem formulationImportance of correct formulationMathematical versus real-worldproblemsUsing a standard approachHelp from othersSources of softwareVerifying resultsUsing known techniques on unknownproblemsExamplesThe InternalProblemRateofReturnProblem statementFormulationsMethods and AlgorithmsPrograms or PackagesSome solutionsAssessmentData Fitting and ModellingProblem StatementFormulationsMethods and AlgorithmsPrograms or PackagesSome solutionsAssessmentTrajectories of SpacecraftProblem statementFormulationsMethods and AlgorithmsPrograms or PackagesSome solutionsAssessmentSimulating a Hiring ProcessProblem StatementFormulationsMethods and AlgorithmsPrograms or PackagesSome solutionsAssessment0: PREFACE AND CONTENTSChapter 18:18.118.218.318.418.518.618.7A Program Efficiency Study: theCholesky DecompositionPurpose of the studyThe programs and systems comparedMeasuring the differencesProgram sizes and compiler optionsTime differences from programalternativesCompiler and arithmetic influencesProcessor and configuration timedifferencesvChapter 20:20.120.220.320.420.6Your Own Strategy for ScientificComputing on PCsIdentifying needs and wantsAcquiring the right computingenvironmentsTools and methodsAdd-ons, extras and flexibilityPersonal Choice and SatisfactionBibliographyFigures and TablesChapter 19:19.119.219.319.419.519.619.7Case study: graphical tools fordata analysisIndexPurpose of the studyExample data for analysisDisplay characteristicsChoices of graphical toolsDisplaying level and variabilityDisplaying relative measurementsDisplaying patterns and outliersThis book is made available in PostScript™ form via Internet FTP servers.

The copyright to this workbelongs to the authors. You may copy the PostScript files for this work and print off the file SCPCDOC.PSfreely. If you print off the files of the book itself you then owe the authors a licence fee of $10.The book (and related materials) may be obtained by anonymous FTP from:MacNash.admin.uottawa.caThe full work is approximately 200 pages long and the PostScript files occupy about 4 megabytes ofstorage.viCopyright © 1984, 1994 J C & M M NashSCIENTIFIC COMPUTING WITH PCsNash Information Services Inc., 1975 Bel Air Drive, Ottawa, ON K2C 0X1 CanadaCopy for:Dr.