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It is also available online at www. You can also get a copy from your local office or by calling our toll-free number , or at our TTY number , between 7 a.
Monday through Friday. The Red Book contains a general description of our disability-related policies. For information specific to your situation regarding eligibility or benefits, you may need to contact us. The Red Book, including the Spanish language version, is available online at: www. Iterative methods for sparse linear systems 1st edition This book, originally published in by PWS, is now out of print.
I revised the manuscript and I am making the post script available for those who want to use it. A new edition of this book is now available from SIAM, see above. Compressed gzip tar file zipped zip post-script files zipped zip PDF files Access to all files compressed and uncompressed from the ftp directory.
Once you download the files you will need to unpack them and you will find 4 separate PDF files iter1. You can also get directly the individual PDF or post-script files fourth of the options given above. Is there any conflict between requirements? Is each requirement achievable in the proposed technical environment? Is each requirement testable? Requirements Specification Introduction Goals and objectives of the software Context of the computer-based system.
Information Description: Problem description Information content, flow and structure Hardware,software, human interfaces for external system elements and internal software functions. Functional Description: Diagrammatic representation of functions Processing narrative for each function. Interplay among functions Design constraints. Requirements Specification Contd. Behavioural Description: Response to external events and internal controls Validation Criteria: Classes of tests to be performed to validate functions, performance and constraints Bibliography: Software engineering documentation Technical references Vendor literature Standards Appendix: Tabular data Detailed description of algorithms Charts, graphs and other such material.
Requirements Validation by both the software developer and the customer. First review for completeness consistency accuracy. Requirements Management Activities that help the project team to identify, control and track requirements and changes to requirements Create traceability tables: Features traceability table:how requirements relate to user observable features Source traceability table: source of each requirement Dependency traceability table: relationship between requirements Subsystem traceability table: categorization of requirements Interface traceability table: relationship of requirements to internal and external interfaces.
A model is a simplification of reality. It provides a blue print of a system. A good model includes elements that have broad effects and omit elements that are not relevant to system.
Principles of Modeling 1. Every model may be expressed in different levels of precision 2. The best models are connected to reality 3. No single model is sufficient. Analysis Modeling Rules of Thumb Start with high level of abstraction: dont get bogged down by details; dont try to explain at this stage how the system will work Identify elements that add to the overall understanding of the requirements Minimize interconnections Understand different requirements of different stake holders and present them the view useful to them Keep the model as simple as possible.
Dont go by just current requirements; anticipate future requirements Identify recurring patterns reusable components. Usage Scenarios Use cases A use case specifies behavior of a system or part of a system and is a description of a set of sequence of actions, including variants that a system performs to yield an observable result of value to an actor.
Validate user Sensors:: Calibrate location. Actors An actor represents a coherent set of roles that users of use case play when interacting with the use cases.
Establish the context of the system by identifying the actors that surroun For each actor consider the behavior that each expects or requires the system to provide. Name these common behaviors as use cases Factor common behavior into new use case that are used by others;. Is focused on communication one aspect of a systems static use case Contains only those use cases and actors that are essential to understand that aspect Provides details consistent with its level of abstraction; you should expose only those adornments that are essential to understanding.
Is not so minimalist simple as to misinform the reader about semantics that are important. Give it a name that communicates its purpose Lay out its elements to minimize lines that cross Organize elements spatially so that behaviors and roles that are semantically close are laid out physically close.
Use notes and color as visual cues to draw attention to important featu of your diagram Try not to show too many kinds of relationships. If you have any complicated relationships, take these elements to another diagram.
Prepare Use cases for the following: a. Elevator ride to top floor b. Operation of a car cruise control in heavy traffic. Direction and Naming of Flows Process explosion numbering of sub-processes Process specification. Structured English Example If previous reading and new reading match then perform 'status-check' If status is 'dead' then calculate bills based on average consumption Else compute bill based on actual consumption status-check If meter does not register any change after switching on any electrical device then meter status is 'dead' Else meter status is 'ok'.
Structured English compared with Normal English Loose, normal English: In the case of 'Bill', a master file is updated with the bill that is consumer account number and bill date. A control file is also to be updated for the 'total bill amount'. A similar treatment is to be given to 'Payment.
Modality Modality of a relationship is 0, if there is no explicit need for the relationship to occur 1, if the occurrence of relationship is mandatory.
Selection Criteria for Classes Is the information about it to be remembered for the system to function? It must have operations that can change its values in some way It should have multiple attributes There must be some attributes that are applicable to all the instances of the class There must be some operations that are applicable to all the instances of the class External entities.
Specifying Attributes What data items fully define the class? Defining Operations Operations define the behavior of an object Broad categories That manipulate data in some way That perform a computation That inquire about the state of an object That monitor an object for the occurrence of a controlling event.
Scenario Outcome: Insurance company pays claim 1. Claimant submits claim with substantiating data. Insurance company verifies claimant owns a valid policy failure here probably means goal failure 3. Insurance company assigns agent to examine case. Agent verifies all details are within policy guidelines. Insurance company pays claimant implies all preceding goals managed to pass.
Extensions 1a. Submitted data is incomplete: 1a1. Insurance company requests missing information 1a2. Claimant supplies missing information. Claimant does not own a valid policy: 2a1. Insurance company declines claim, notifies claimant, records all this, terminates proceedings.
No agents are available at this time 3a1. What does the insurance company do here? Accident violates basic policy guidelines: 4a1. Accident violates some minor policy guidelines: 4b1. Insurance company begins negotiation with claimant as to degree of payment to be made. The greatest value of the use case does not lie in the main scenario, but in alternative behaviors. Payment is a. Conduct interviews Make list of classes, functions Make list of constraints Elicit requirements Formal prioritization?
Swimlane Diagrams Variation of Activity Diagram Additional information on which actor is involved in which function. Initial state and final state Initial state indicates starting place for the state machine or substate and is represented as a filled black circle.
Final state indicates that the execution of the state machine or enclosing state has been completed and is represented as a filled black circle surrounded by an unfilled circle. Sequence Diagram Emphasizes the time ordering of message Shows a set of objects and message sent by and received by those objects These objects may be instances of classes, collaborations, components and nodes. The Anatomy of Sequence Diagrams Object life line represents the existence of an object over a period of time If any object is created during a transaction, then its lifeline starts from the receipt of that message.
Similarly objects may be destroyed before the end of the transaction Focus of control: period of time during which an object is performing an action, either directly or through a subordinate procedure; represented by a thin rectangle. What is System Design? Detailing how the proposed system can be realized into a working model. What is Abstraction? Any model that includes the most important, essential, or distinguishing aspects of something while suppressing or ignoring less important, immaterial, or diversionary details.
The result of removing distinctions so as to emphasize commonalties The essential characteristics of an entity that distinguish it from all other kinds of entities. Defines a boundary relative to the perspective of the viewer Is not a concrete manifestation, denotes the ideal essence of something.
This implies that different people would build radically different abstractions for the same concept. Abstraction and Encapsulation Encapsulation as a counterpoint to abstraction An abstraction highlights the important aspects of an object.
Encapsulation hides the internal details of the object. A well-encapsulated object allows other objects to use it without depending on any internal details. What is Modularity? The breaking up of something complex into manageable pieces Order Entry. Data Modelling Translate conceptual model into a data model eg deriving a relational data model from entity relationship model Tool: Normalization.
Normalization Record design technique to avoid some update anomalies First Normal Form: no repeating groups Second Normal Form: all non-key data items should depend on key only Third Normal Form: no non-key item should depend on another non-key item. Design Principles Do not confine to a single pre-judged solution; consider alternatives Traceability to analysis Suitability to the structure of the problem Easily identifiable relationship of software functions to user function Uniformity in style and format Modularity.
Modularity Module is a manageable unit performing a well-defined task Modules contain instructions and data for performing a particular task. Modules have well-defined interfaces. Advantages: Maintainability, Reusability. Measures of Modularity Cohesion: how well the elements fit together in a module Coupling: strength of interconnection between modules Desired: High Cohesion and Low Coupling. Place the user in control 2. Reduce the users memory load 3.
Make the interface consistent. Interface Analysis and Design Models Know the user, know the tasks Categorize users as novices, professionals and experts Screen should match the users mental model Look and feel Help Physical environment of the location Physical location Users posture Space, light, noise constraints Special human factor considerations. Command labeling Command options control sequence, function key Ease of remembering commands Facility of customization by the user Self-explanatory labels Consistency of submenus with main menu.
Software Testing - Objectives Process of executing a program with an intent of finding an error. Verification and Validation Verification refers to the set of activities that ensure that software correctly implements the specific function Validation refers to a different set of activities that ensure that the software is built as per customer requirements Verification: Are we building the product right?
Validation: Are we building the right product? The Realities of Software Testing It is impossible to test a program completely because of very large possibilities Software testing is a risk based exercise: Cost of testing vs. Unit Testing Process of testing individual units of software in isolation of other parts of the program.
This test is conducted to test Functionality: should produce expected result for a given input value Performance: response time, execution time, throughput, memory utilization, traffic in communication channels Stress: Checking the limits Structure: processing logic.
Integration Testing If they all work individually, they will work, when we put them together and the whole product will also work False; Interfacing can create problems Hence overall product is checked. Integration Testing Systematic technique for assembling software while at the same time conducting tests to uncover errors associated with interfacing Tests for Interface integrity Functional validity Performance.
Regression Testing The process of rerunning a portion of software to check that changes have not introduced new errors Obj: to ensure that all aspects of an application system remain functional after testing Should be conducted after a predetermined number of changes in the application system Significant during maintenance too.
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