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• The Allure of Cloud Computing for VoIP

  The promise of immediate payback is strong motivation to move all networking services &#150; even voice &#150; to the cloud, but it isn't quite that simple.

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• Our Oracle Recruitment Team is Growing - Multiple Job Opportunities in Bangalore, India

  - by david.talamelli

  DON"T GET STUCK IN THE MATRIXSEE YOUR FUTUREVISIT THE ORACLE The position(s): CORPORATE RECRUITING RESEARCH ANALYST(S) ABOUT ORACLE Oracle's business is information--how to manage it, use it, share it, protect it. For three decades, Oracle, the world's largest enterprise software company, has provided the software and services that allow organizations to get the most up-to-date and accurate information from their business systems. Only Oracle powers the information-driven enterprise by offering a complete, integrated solution for every segment of the process industry. When you run Oracle applications on Oracle technology, you speed implementation, optimize performance, and maximize ROI. Great hiring doesn't happen by accident; it's the culmination of a series of thoughtfully planned and well executed events. At the core of any hiring process is a sourcing strategy. This is where you come in... Do you want to be a part of a world-class recruiting organization that's on the cutting edge of technology? Would you like to experience a rewarding work environment that allows you to further develop your skills, while giving you the opportunity to develop new skills? If you answered yes, you've taken your first step towards a future with Oracle. We are building a Research Team to support our North America Recruitment Team, and we need creative, smart, and ambitious individuals to help us drive our research department forward. Oracle has a track record for employing and developing the very best in the industry. We invest generously in employee development, training and resources. Be a part of the most progressive internal recruiting team in the industry. For more information about Oracle, please visit our Web site at http://www.oracle.com Escape the hum drum job world matrix, visit the Oracle and be a part of a winning team, apply today. POSITION: Corporate Recruiting Research Analyst LOCATION: Bangalore, India RESPONSIBILITIES: •Develop candidate pipeline using Web 2.0 sourcing strategies and advanced Boolean Search techniques to support U.S. Recruiting Team for various job functions and levels. •Engage with assigned recruiters to understand the supported business as well as the recruiting requirements; partner with recruiters to meet expectations and deliver a qualified pipeline of candidates. •Source candidates to include both active and passive job seekers to provide a strong pipeline of qualified candidates for each recruiter; exercise creativity to find candidates using Oracle's advanced sourcing tools/techniques. •Fully evaluate candidate's background against the requirements provided by recruiter, and process leads using ATS (Applicant Tracking System). •Manage your efforts efficiently; maintain the highest levels of client satisfaction as well as strong operations and reporting of research activities. PREFERRED QUALIFICATIONS: •Fluent in English, with excellent written and oral communication skills. •Undergraduate degree required, MBA or Masters preferred. •Proficiency with Boolean Search techniques desired. •Ability to learn new software applications quickly. •Must be able to accommodate some U.S. evening hours. •Strong organization and attention to detail skills. •Prior HR or corporate in-house recruiting experiences a plus. •The fire in the belly to learn new ideas and succeed. •Ability to work in team and individual environments. This is an excellent opportunity to join Oracle in our Bangalore Offices. Interested applicants can send their resume to [email protected] or contact David on +61 3 8616 3364

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• Markus Zirn, "Big Data with CEP and SOA" @ SOA, Cloud &amp; Service Technology Symposium 2012

  - by JuergenKress

  ORACLE PROMOTIONAL DISCOUNT FOR EXCLUSIVE ORACLE DISCOUNT, ENTER PROMO CODE: DJMXZ370 Early-Bird Registration is Now Open with Special Pricing! Register before July 1, 2012 to qualify for discounts. Visit the Registration page for details. The International SOA, Cloud + Service Technology Symposium is a yearly event that features the top experts and authors from around the world, providing a series of keynotes, talks, demonstrations, and panels, as well as training and certification workshops - all dedicated to empowering IT professionals to realize modern service technologies and practices in the real world. Click here for a two-page printable conference overview (PDF). Big Data with CEP and SOA - September 25, 2012 - 14:15 Speaker: Markus Zirn, Oracle and Baz Kuthi, Avocent The "Big Data" trend is driving new kinds of IT projects that process machine-generated data. Such projects store and mine using Hadoop/ Map Reduce, but they also analyze streaming data via event-driven patterns, which can be called "Fast Data" complementary to "Big Data". This session highlights how "Big Data" and "Fast Data" design patterns can be combined with SOA design principles into modern, event-driven architectures. We will describe specific architectures that combines CEP, Distributed Caching, Event-driven Network, SOA Composites, Application Development Framework, as well as Hadoop. Architecture patterns include pre-processing and filtering event streams as close as possible to the event source, in memory master data for event pattern matching, event-driven user interfaces as well as distributed event processing. Focus is on how "Fast Data" requirements are elegantly integrated into a traditional SOA architecture. Markus Zirn is Vice President of Product Management covering Oracle SOA Suite, SOA Governance, Application Integration Architecture, BPM, BPM Solutions, Complex Event Processing and UPK, an end user learning solution. He is the author of “The BPEL Cookbook” (rated best book on Services Oriented Architecture in 2007) as well as “Fusion Middleware Patterns”. Previously, he was a management consultant with Booz Allen & Hamilton’s High Tech practice in Duesseldorf as well as San Francisco and Vice President of Product Marketing at QUIQ. Mr. Zirn holds a Masters of Electrical Engineering from the University of Karlsruhe and is an alumnus of the Tripartite program, a joint European degree from the University of Karlsruhe, Germany, the University of Southampton, UK, and ESIEE, France. KEYNOTES & SPEAKERS More than 80 international subject matter experts will be speaking at the Symposium. Below are confirmed keynotes and speakers so far. Over 50% of the agenda has not yet been finalized. Many more speakers to come. View the partial program calendars on the Conference Agenda page. CONFERENCE THEMES & TRACKS Cloud Computing Architecture & Patterns New SOA & Service-Orientation Practices & Models Emerging Service Technology Innovation Service Modeling & Analysis Techniques Service Infrastructure & Virtualization Cloud-based Enterprise Architecture Business Planning for Cloud Computing Projects Real World Case Studies Semantic Web Technologies (with & without the Cloud) Governance Frameworks for SOA and/or Cloud Computing Projects Service Engineering & Service Programming Techniques Interactive Services & the Human Factor New REST & Web Services Tools & Techniques Oracle Specialized SOA & BPM Partners Oracle Specialized partners have proven their skills by certifications and customer references. To find a local Specialized partner please visit http://solutions.oracle.com SOA & BPM Partner Community For regular information on Oracle SOA Suite become a member in the SOA & BPM Partner Community for registration please visit  www.oracle.com/goto/emea/soa (OPN account required) If you need support with your account please contact the Oracle Partner Business Center. Blog Twitter LinkedIn Mix Forum Technorati Tags: Markus Zirn,SOA Symposium,Thomas Erl,SOA Community,Oracle SOA,Oracle BPM,BPM Community,OPN,Jürgen Kress

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• Tough Decisions

  - by Johnm

  There was once a thriving business that employed two Database Administrators, Sam and Jim. Both DBAs were certified, educated and highly talented in their skill sets. During lunch breaks these two DBAs were often found together discussing best practices, troubleshooting techniques and the latest release notes for the upcoming version of SQL Server. They genuinely loved what they did. The maintenance of the first database was the responsibility of Sam. He was the architect of this server's setup and he was very meticulous in its configuration. He regularly monitored the health of the database, validated backup files and regularly adhered to the best practices that were advocated by well respected professionals. He was very proud of the fact that there was never a database that he managed that lost data or performed poorly. The maintenance of the second database was the responsibility of Jim. He too was the architect of this server's setup. At the time that he built this server, his understanding of the finer details of configuration were not as clear as they are today. The server was build on a shoestring budget and with very little time for testing and implementation. Jim often monitored the health of the database; but in more of a reactionary mode due to user complaints of slowness or failed transactions. Deadlocks abounded and the backup files were never validated. One day, the announcement was made that revealed that the business had hit financially hard times. Budgets were being cut, limitation on spending was implemented and the reduction in full-time staff was required. Since having two DBAs was regarded a luxury by many, this meant that either Sam or Jim were about to find themselves out of a job. Sam and Jim's boss, Frank, was faced with a very tough decision. Sam's performance was flawless. His techniques and practices were perfection. The databases he managed were reliable and efficient. His solutions are "by the book". When given a task it is certain that, while it may take a little longer, it will be done right the first time. Jim's techniques and practices were not perfect; but effective and responsive. He made mistakes regularly; but he shows that he learns from them and they often result in innovative solutions. When given a task it is certain that, while the results may require some tweaking, it will be done on time and under budget. You are Frank's best friend. He approaches you and presents this scenario. He must layoff one of his valued DBAs the very next morning. Frank asks you: "All else being equal, who would you let go? and Why?" Another pertinent question is raised: "Regardless of good times or bad, if you had to choose, which DBA would you want on your team when tough challenges arise?" Your response is. (This is where you enter a comment below)

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• WCF RIA Services DomainContext Abstraction Strategies–Say That 10 Times!

  - by dwahlin

  The DomainContext available with WCF RIA Services provides a lot of functionality that can help track object state and handle making calls from a Silverlight client to a DomainService. One of the questions I get quite often in our Silverlight training classes (and see often in various forums and other areas) is how the DomainContext can be abstracted out of ViewModel classes when using the MVVM pattern in Silverlight applications. It’s not something that’s super obvious at first especially if you don’t work with delegates a lot, but it can definitely be done. There are various techniques and strategies that can be used but I thought I’d share some of the core techniques I find useful. To start, let’s assume you have the following ViewModel class (this is from my Silverlight Firestarter talk available to watch online here if you’re interested in getting started with WCF RIA Services): public class AdminViewModel : ViewModelBase { BookClubContext _Context = new BookClubContext(); public AdminViewModel() { if (!DesignerProperties.IsInDesignTool) { LoadBooks(); } } private void LoadBooks() { _Context.Load(_Context.GetBooksQuery(), LoadBooksCallback, null); } private void LoadBooksCallback(LoadOperation<Book> books) { Books = new ObservableCollection<Book>(books.Entities); } } Notice that BookClubContext is being used directly in the ViewModel class. There’s nothing wrong with that of course, but if other ViewModel objects need to load books then code would be duplicated across classes. Plus, the ViewModel has direct knowledge of how to load data and I like to make it more loosely-coupled. To do this I create what I call a “Service Agent” class. This class is responsible for getting data from the DomainService and returning it to a ViewModel. It only knows how to get and return data but doesn’t know how data should be stored and isn’t used with data binding operations. An example of a simple ServiceAgent class is shown next. Notice that I’m using the Action<T> delegate to handle callbacks from the ServiceAgent to the ViewModel object. Because LoadBooks accepts an Action<ObservableCollection<Book>>, the callback method in the ViewModel must accept ObservableCollection<Book> as a parameter. The callback is initiated by calling the Invoke method exposed by Action<T>: public class ServiceAgent { BookClubContext _Context = new BookClubContext(); public void LoadBooks(Action<ObservableCollection<Book>> callback) { _Context.Load(_Context.GetBooksQuery(), LoadBooksCallback, callback); } public void LoadBooksCallback(LoadOperation<Book> lo) { //Check for errors of course...keeping this brief var books = new ObservableCollection<Book>(lo.Entities); var action = (Action<ObservableCollection<Book>>)lo.UserState; action.Invoke(books); } } This can be simplified by taking advantage of lambda expressions. Notice that in the following code I don’t have a separate callback method and don’t have to worry about passing any user state or casting any user state (the user state is the 3rd parameter in the _Context.Load method call shown above). public class ServiceAgent { BookClubContext _Context = new BookClubContext(); public void LoadBooks(Action<ObservableCollection<Book>> callback) { _Context.Load(_Context.GetBooksQuery(), (lo) => { var books = new ObservableCollection<Book>(lo.Entities); callback.Invoke(books); }, null); } } A ViewModel class can then call into the ServiceAgent to retrieve books yet never know anything about the DomainContext object or even know how data is loaded behind the scenes: public class AdminViewModel : ViewModelBase { ServiceAgent _ServiceAgent = new ServiceAgent(); public AdminViewModel() { if (!DesignerProperties.IsInDesignTool) { LoadBooks(); } } private void LoadBooks() { _ServiceAgent.LoadBooks(LoadBooksCallback); } private void LoadBooksCallback(ObservableCollection<Book> books) { Books = books } } You could also handle the LoadBooksCallback method using a lambda if you wanted to minimize code just like I did earlier with the LoadBooks method in the ServiceAgent class.  If you’re into Dependency Injection (DI), you could create an interface for the ServiceAgent type, reference it in the ViewModel and then inject in the object to use at runtime. There are certainly other techniques and strategies that can be used, but the code shown here provides an introductory look at the topic that should help get you started abstracting the DomainContext out of your ViewModel classes when using WCF RIA Services in Silverlight applications.

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• Gamify your Web

  - by Isabel F. Peñuelas

  Yesterday Valencia welcomed the Gamification World Congress that I follow virtually through #GWC2012. BBVA, Iberia, Ligeresa, Axe, Wayra, ESADE, GlaxoSmithKline, Macmillan, Gamisfaction, Nomaders, Blaffin were among the companies presenting success stories on gaming. It has been proved that people remember things easily when an emotion is created. The marketing expectations around Gamification techniques have a lot to do with Neuromarketing theories. There are a lot of expectations on internal enterprise Gamification. In the public Web some sectors are taking the lead on following the trend. The Gartner Analyst Brian Burke opened another Gamification recent event in Madrid remembering that “Gamification is mostly about Engagement”, and this can be applied both to customers or employees. Gamification and Banking The experience of the Spanish Financial Group BBVA that just launched BBVA Game was also presented a week ago at the BBVA Innovation Centre during the event “Gamification & Banking: a fad or a serious business?” . One of the objectives of the BBVA Game was to double the name of registered users. “People like the efficiency of the online channel want to keep a one-to-one contact with the brand”-explained Bernardo Crespo. Another interested data coming out the BBVA presentation was that “only 20% of Spanish users –out of the total holders of Bank Accounts in the country- is familiar with the use of a Web Site to consult their bank accounts”, the project aims also to reverse this situation helping people to learn making a heavy use of the Video in the gaming context. In general Banking presenters seem to agree that Gamification techniques are helping to increase the time spent on the Web. Gamification and Health Using Gamification techniques for chronic illness rehabilitation was another topic of the World Congress. Here you can find some ideas and experiences What can games do for the health (In Spanish) I have personally started my own mental-health gaming project at http://www.lumosity.com/ Gamification in the Enterprise I really recommend Reading this excellent post of Ultan ÓBroin my Introduction to Gamification and Applications. Employee´s motivation and learning are experiencing a 360º turn and it looks than some of us will become soon the Dragon of the year instead of the Employee of the Year. Using Web 2.0 Tools for Gamification Projects  What type of tools do we need for a quick-win Gamification project? To certain extend Gamification can be considered an evolution of the participative Web. Badging, avatars, points and awards, leader boards, progress charts, virtual currencies, gifting and giving challenges and quests are common components and elements. The Web is offering new development frameworks to that purpose as this Avatar Framework from Paypal or Badgeville to include in web applications. Besides, tools to create communities around a game are required to comment, share and vote players as well as for an efficient multimedia management. Due to its entirely open architecture, its community features, and its multimedia and imaging solutions is were I see WebCenter as a tool helping brands to success. Link to Sources & Recommended Readings YouTube Video of BBVAGame presentation Where To Apply Gamification In Your Incentive Jim Calhoun Cancer Challenge Ride and Walkh For my Spanish Readers El aburrimiento es el enemigo número uno del éxito

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• Lost in Translation – Common Mistakes Interpreting Patterns – Mark Simpson, Griffiths-Waite @ SOA, Cloud & Service Technology Symposium 2012

  - by JuergenKress

  ORACLE PROMOTIONAL DISCOUNT FOR EXCLUSIVE ORACLE DISCOUNT, ENTER PROMO CODE: DJMXZ370 For details please visit the registration page International SOA, Cloud + Service Technology Symposium is a yearly event that features the top experts and authors from around the world, providing a series of keynotes, talks, demonstrations, and panels, as well as training and certification workshops - all dedicated to empowering IT professionals to realize modern service technologies and practices in the real world. Click here for a two-page printable conference overview (PDF). Speaker: Mark Simpson, Griffiths-Waite Mark has been specialising in Oracle technology for 13 years, the last 10 of these with Griffiths Waite. Mark leads our SOA technology practice (covering SOA, Business Process Management and Enterprise Architecture). He is a much sought after presenter on the Oracle and SOA conference circuits, and a respected authority on these technologies. Mark has advised a host of UK leading organisations on the deployment of BPM / SOA solutions. Working closely with Oracle US Product Development Mark has contributed to Oracle's SOA Methodology and Oracle's SOA Maturity Model. Lost in Translation – Common Mistakes Interpreting Patterns Learn how small misinterpretations of high-level design patterns can have large and costly project ramifications. Good SOA design benefits from the use of a reference architecture and standardised design patterns. However both of these concepts give an abstracted view of the intended solution, which needs to be interpreted to become realised. A reference implementation is important to demonstrate how key design guidelines can be implemented in the toolset of choice, but the main success factor is how these are used through the build and post live phases of the project. This session will introduce practical design patterns with supporting implementation examples that, if used correctly, will give long term benefit. We will highlight implementations where misinterpretations or misalignment from pattern aims have led to issues post implementation. The session will add depth to the pattern discussions you are already having enabling confidence in proceeding to the next level of realisation whilst considering how they may be implemented within your solution and chosen toolset. September 25, 2012 - 13:55 KEYNOTES & SPEAKERS More than 80 international subject matter experts will be speaking at the Symposium. Below are confirmed keynotes and speakers so far. Over 50% of the agenda has not yet been finalized. Many more speakers to come. View the partial program calendars on the Conference Agenda page. CONFERENCE THEMES & TRACKS Cloud Computing Architecture & Patterns New SOA & Service-Orientation Practices & Models Emerging Service Technology Innovation Service Modeling & Analysis Techniques Service Infrastructure & Virtualization Cloud-based Enterprise Architecture Business Planning for Cloud Computing Projects Real World Case Studies Semantic Web Technologies (with & without the Cloud) Governance Frameworks for SOA and/or Cloud Computing Projects Service Engineering & Service Programming Techniques Interactive Services & the Human Factor New REST & Web Services Tools & Techniques Oracle Specialized SOA & BPM Partners Oracle Specialized partners have proven their skills by certifications and customer references. To find a local Specialized partner please visit http://solutions.oracle.com SOA & BPM Partner Community For regular information on Oracle SOA Suite become a member in the SOA & BPM Partner Community for registration please visit  www.oracle.com/goto/emea/soa (OPN account required) If you need support with your account please contact the Oracle Partner Business Center. Blog Twitter LinkedIn Mix Forum Technorati Tags: Mark Simpson,Griffiths Waite,SOA Patterns,SOA Symposium,Thomas Erl,SOA Community,Oracle SOA,Oracle BPM,BPM,Community,OPN,Jürgen Kress

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• Problems with Continuous Integration (CI) in TFS during Build Automation?

  - by Steve Johnson

  Hi all, I am using TFS 2008 and Visual Studio and my boss has instructed me to implement Build Automation for Development and Release builds for a web Project. I am a total newbie in Build Automation. There are multiple developers working on the project on different machines using Visual Studio 2008 team System. Source is already being maintained on TFS 2008. SQL Server in Use is SQL Server 2000 and hosted IIS is IIS 7.5 on Windows Server 2008 x64. I have searched over the net and found Continuous Integration and Nightly Builds as two important Build Automation techniques. I was just wondering of any disadvantages associated with both the methodologies (CI and Nightly Builds). If someone could guide me to a working tutorial that explains both techniques the it would be quite helpful. Please also tell the requirements of IIS, SQL Server and any other that might be pre-requisite to implement build automation. Also i would like to know whether there are other techniques that are better then CI? Replies and discussion much appreciated. Thanks

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• Help! I've learned jQuery... now I want to learn JavaScript

  - by Derek Adair

  I am a self-taught web developer/programmer. I started out about two years ago by learning how to make simple dynamic websites with HTML/CSS/PHP. Then I started dabbling with animation... Enter jQuery I've become quite proficient with jQuery over the last year and I've even started making my own plugins. I've spent most of my effort learning how to beautify websites with fancy effects and what not. Upon tackling my first full-blown application, I realized how under-developed my knowledge of JavaScript actually is. jQuery has allowed me to rely on its framework so heavily that I rarely use any interesting functions, techniques, or whatever that are 'native' to the JavaScript language. For example: I have a basic understanding of what a closure is... but I am unsure where this technique can actually benefit me. Although as I understand it, that's what my jQuery plugins do with (function ($){//plugin code here})(jQuery). I've seen many posts/blogs/whatever about memory leaks and circular references which is concerning. I'm frustrated because I can wrap my head around the basic concepts of what these are just by reading the articles, but I'm finding that the deeper I go the more I don't understand. The vocabulary alone is burdensome. Let alone how to actually use these techniques/functions/language features. I am trying to figure out what I don't know I'm looking to gather any advice, techniques, articles, books, videos, snippets, examples, potential pitfalls... really anything you have regarding application development with JavaScript/jQuery.

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• PHP Performance Metrics

  - by bigstylee

  I am currently developing a PHP MVC Framework for a personal project. While I am developing the framework I am interested to see any notable performance by implementing different techniques for optimization. I have implemented a crude BenchMark class that logs mircotime. The problem is I have no frame of reference for execution times. I am very near the beginnig of this project with a database connection and a few queries but no output (bar some debugging text and BenchMark log). I have a current execution time of 0.01917 seconds. I was expecting this to be lower but as I said before I have no frame of reference. I appreciate there are many variables to take into account when juding performance but I am hoping to find some sort of metric to a) techniques to measure performance for example requests per second and b) compare results for example; how a "moderately" sized PHP application on a "standard" webserver will perform. I appreciate "moderately" and "standard" are very subjective words so perhaps a table of known execution times for a particular application (eg StackOverFlow's executing time). What are other techniques of measuring performance are there other than execution time? When looking at MVC Framework Performance Comparisom it talks about Requests Per Second (RPS). How is this calculated? I am guessing with my current execution time of 0.01917 seconds can handle 52 RPS (= 1 / 0.01917 ). This seems to be significantly lower than that quoted on the graph especially when you consider my current limited funcitonality.

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• Access cost of dynamically created objects with dynamically allocated members

  - by user343547

  I'm building an application which will have dynamic allocated objects of type A each with a dynamically allocated member (v) similar to the below class class A { int a; int b; int* v; }; where: The memory for v will be allocated in the constructor. v will be allocated once when an object of type A is created and will never need to be resized. The size of v will vary across all instances of A. The application will potentially have a huge number of such objects and mostly need to stream a large number of these objects through the CPU but only need to perform very simple computations on the members variables. Could having v dynamically allocated could mean that an instance of A and its member v are not located together in memory? What tools and techniques can be used to test if this fragmentation is a performance bottleneck? If such fragmentation is a performance issue, are there any techniques that could allow A and v to allocated in a continuous region of memory? Or are there any techniques to aid memory access such as pre-fetching scheme? for example get an object of type A operate on the other member variables whilst pre-fetching v. If the size of v or an acceptable maximum size could be known at compile time would replacing v with a fixed sized array like int v[max_length] lead to better performance? The target platforms are standard desktop machines with x86/AMD64 processors, Windows or Linux OSes and compiled using either GCC or MSVC compilers.

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• Integrating HTML into Silverlight Applications

  - by dwahlin

  Looking for a way to display HTML content within a Silverlight application? If you haven’t tried doing that before it can be challenging at first until you know a few tricks of the trade.  Being able to display HTML is especially handy when you’re required to display RSS feeds (with embedded HTML), SQL Server Reporting Services reports, PDF files (not actually HTML – but the techniques discussed will work), or other HTML content.  In this post I'll discuss three options for displaying HTML content in Silverlight applications and describe how my company is using these techniques in client applications. Displaying HTML Overlays If you need to display HTML over a Silverlight application (such as an RSS feed containing HTML data in it) you’ll need to set the Silverlight control’s windowless parameter to true. This can be done using the object tag as shown next: <object data="data:application/x-silverlight-2," type="application/x-silverlight-2" width="100%" height="100%"> <param name="source" value="ClientBin/HTMLAndSilverlight.xap"/> <param name="onError" value="onSilverlightError" /> <param name="background" value="white" /> <param name="minRuntimeVersion" value="4.0.50401.0" /> <param name="autoUpgrade" value="true" /> <param name="windowless" value="true" /> <a href="http://go.microsoft.com/fwlink/?LinkID=149156&v=4.0.50401.0" style="text-decoration:none"> <img src="http://go.microsoft.com/fwlink/?LinkId=161376" alt="Get Microsoft Silverlight" style="border-style:none"/> </a> </object> By setting the control to “windowless” you can overlay HTML objects by using absolute positioning and other CSS techniques. Keep in mind that on Windows machines the windowless setting can result in a performance hit when complex animations or HD video are running since the plug-in content is displayed directly by the browser window. It goes without saying that you should only set windowless to true when you really need the functionality it offers. For example, if I want to display my blog’s RSS content on top of a Silverlight application I could set windowless to true and create a user control that grabbed the content and output it using a DataList control: <style type="text/css"> a {text-decoration:none;font-weight:bold;font-size:14pt;} </style> <div style="margin-top:10px; margin-left:10px;margin-right:5px;"> <asp:DataList ID="RSSDataList" runat="server" DataSourceID="RSSDataSource"> <ItemTemplate> <a href='<%# XPath("link") %>'><%# XPath("title") %></a> <br /> <%# XPath("description") %> <br /> </ItemTemplate> </asp:DataList> <asp:XmlDataSource ID="RSSDataSource" DataFile="http://weblogs.asp.net/dwahlin/rss.aspx" XPath="rss/channel/item" CacheDuration="60" runat="server" /> </div> The user control can then be placed in the page hosting the Silverlight control as shown below. This example adds a Close button, additional content to display in the overlay window and the HTML generated from the user control. <div id="RSSDiv"> <div style="background-color:#484848;border:1px solid black;height:35px;width:100%;"> <img alt="Close Button" align="right" src="Images/Close.png" onclick="HideOverlay();" style="cursor:pointer;" /> </div> <div style="overflow:auto;width:800px;height:565px;"> <div style="float:left;width:100px;height:103px;margin-left:10px;margin-top:5px;"> <img src="http://weblogs.asp.net/blogs/dwahlin/dan2008.jpg" style="border:1px solid Gray" /> </div> <div style="float:left;width:300px;height:103px;margin-top:5px;"> <a href="http://weblogs.asp.net/dwahlin" style="margin-left:10px;font-size:20pt;">Dan Wahlin's Blog</a> </div> <br /><br /><br /> <div style="clear:both;margin-top:20px;"> <uc:BlogRoller ID="BlogRoller" runat="server" /> </div> </div> </div> Of course, we wouldn’t want the RSS HTML content to be shown until requested. Once it’s requested the absolute position of where it should show above the Silverlight control can be set using standard CSS styles. The following ID selector named #RSSDiv handles hiding the overlay div shown above and determines where it will be display on the screen. #RSSDiv { background-color:White; position:absolute; top:100px; left:300px; width:800px; height:600px; border:1px solid black; display:none; } Now that the HTML content to display above the Silverlight control is set, how can we show it as a user clicks a HyperlinkButton or other control in the application? Fortunately, Silverlight provides an excellent HTML bridge that allows direct access to content hosted within a page. The following code shows two JavaScript functions that can be called from Siverlight to handle showing or hiding HTML overlay content. The two functions rely on jQuery (http://www.jQuery.com) to make it easy to select HTML objects and manipulate their properties: function ShowOverlay() { rssDiv.css('display', 'block'); } function HideOverlay() { rssDiv.css('display', 'none'); } Calling the ShowOverlay function is as simple as adding the following code into the Silverlight application within a button’s Click event handler: private void OverlayHyperlinkButton_Click(object sender, RoutedEventArgs e) { HtmlPage.Window.Invoke("ShowOverlay"); } The result of setting the Silverlight control’s windowless parameter to true and showing the HTML overlay content is shown in the following screenshot:   Thinking Outside the Box to Show HTML Content Setting the windowless parameter to true may not be a viable option for some Silverlight applications or you may simply want to go about showing HTML content a different way. The next technique I’ll show takes advantage of simple HTML, CSS and JavaScript code to handle showing HTML content while a Silverlight application is running in the browser. Keep in mind that with Silverlight’s HTML bridge feature you can always pop-up HTML content in a new browser window using code similar to the following: System.Windows.Browser.HtmlPage.Window.Navigate( new Uri("http://silverlight.net"), "_blank"); For this example I’ll demonstrate how to hide the Silverlight application while maximizing a container div containing the HTML content to show. This allows HTML content to take up the full screen area of the browser without having to set windowless to true and when done right can make the user feel like they never left the Silverlight application. The following HTML shows several div elements that are used to display HTML within the same browser window as the Silverlight application: <div id="JobPlanDiv"> <div style="vertical-align:middle"> <img alt="Close Button" align="right" src="Images/Close.png" onclick="HideJobPlanIFrame();" style="cursor:pointer;" /> </div> <div id="JobPlan_IFrame_Container" style="height:95%;width:100%;margin-top:37px;"></div> </div> The JobPlanDiv element acts as a container for two other divs that handle showing a close button and hosting an iframe that will be added dynamically at runtime. JobPlanDiv isn’t visible when the Silverlight application loads due to the following ID selector added into the page: #JobPlanDiv { position:absolute; background-color:#484848; overflow:hidden; left:0; top:0; height:100%; width:100%; display:none; } When the HTML content needs to be shown or hidden the JavaScript functions shown next can be used: var jobPlanIFrameID = 'JobPlan_IFrame'; var slHost = null; var jobPlanContainer = null; var jobPlanIFrameContainer = null; var rssDiv = null; $(document).ready(function () { slHost = $('#silverlightControlHost'); jobPlanContainer = $('#JobPlanDiv'); jobPlanIFrameContainer = $('#JobPlan_IFrame_Container'); rssDiv = $('#RSSDiv'); }); function ShowJobPlanIFrame(url) { jobPlanContainer.css('display', 'block'); $('<iframe id="' + jobPlanIFrameID + '" src="' + url + '" style="height:100%;width:100%;" />') .appendTo(jobPlanIFrameContainer); slHost.css('width', '0%'); } function HideJobPlanIFrame() { jobPlanContainer.css('display', 'none'); $('#' + jobPlanIFrameID).remove(); slHost.css('width', '100%'); } ShowJobPlanIFrame() handles showing the JobPlanDiv div and adding an iframe into it dynamically. Once JobPlanDiv is shown, the Silverlight control host has its width set to a value of 0% to allow the control to stay alive while making it invisible to the user. I found that this technique works better across multiple browsers as opposed to manipulating the Silverlight control host div’s display or visibility properties. Now that you’ve seen the code to handle showing and hiding the HTML content area, let’s switch focus to the Silverlight application. As a user clicks on a link such as “View Report” the ShowJobPlanIFrame() JavaScript function needs to be called. The following code handles that task: private void ReportHyperlinkButton_Click(object sender, RoutedEventArgs e) { ShowBrowser(_BaseUrl + "/Report.aspx"); } public void ShowBrowser(string url) { HtmlPage.Window.Invoke("ShowJobPlanIFrame", url); } Any URL can be passed into the ShowBrowser() method which handles invoking the JavaScript function. This includes standard web pages or even PDF files. We’ve used this technique frequently with our SmartPrint control (http://www.smartwebcontrols.com) which converts Silverlight screens into PDF documents and displays them. Here’s an example of the content generated:   Silverlight 4’s WebBrowser Control Both techniques shown to this point work well when Silverlight is running in-browser but not so well when it’s running out-of-browser since there’s no host page that you can access using the HTML bridge. Fortunately, Silverlight 4 provides a WebBrowser control that can be used to perform the same functionality quite easily. We’re currently using it in client applications to display PDF documents, SSRS reports and standard HTML content. Using the WebBrowser control simplifies the application quite a bit since no JavaScript is required if the application only runs out-of-browser. Here’s a simple example of defining the WebBrowser control in XAML. I typically define it in MainPage.xaml when a Silverlight Navigation template is used to create the project so that I can re-use the functionality across multiple screens. <Grid x:Name="WebBrowserGrid" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" Visibility="Collapsed"> <StackPanel HorizontalAlignment="Stretch" VerticalAlignment="Stretch"> <Border Background="#484848" HorizontalAlignment="Stretch" Height="40"> <Image x:Name="WebBrowserImage" Width="100" Height="33" Cursor="Hand" HorizontalAlignment="Right" Source="/HTMLAndSilverlight;component/Assets/Images/Close.png" MouseLeftButtonDown="WebBrowserImage_MouseLeftButtonDown" /> </Border> <WebBrowser x:Name="JobPlanReportWebBrowser" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" /> </StackPanel> </Grid> Looking through the XAML you can see that a close image is defined along with the WebBrowser control. Because the URL that the WebBrowser should navigate to isn’t known at design time no value is assigned to the control’s Source property. If the XAML shown above is left “as is” you’ll find that any HTML content assigned to the WebBrowser doesn’t display properly. This is due to no height or width being set on the control. To handle this issue the following code is added into the XAML’s code-behind file to dynamically determine the height and width of the page and assign it to the WebBrowser. This is done by handling the SizeChanged event. void MainPage_SizeChanged(object sender, SizeChangedEventArgs e) { WebBrowserGrid.Height = JobPlanReportWebBrowser.Height = ActualHeight; WebBrowserGrid.Width = JobPlanReportWebBrowser.Width = ActualWidth; } When the user wants to view HTML content they click a button which executes the code shown in next: public void ShowBrowser(string url) { if (Application.Current.IsRunningOutOfBrowser) { JobPlanReportWebBrowser.NavigateToString("<html><body><iframe src='" + url + "' style='width:100%;height:97%;' /></body></html>"); WebBrowserGrid.Visibility = Visibility.Visible; } else { HtmlPage.Window.Invoke("ShowJobPlanIFrame", url); } } private void WebBrowserImage_MouseLeftButtonDown(object sender, MouseButtonEventArgs e) { WebBrowserGrid.Visibility = Visibility.Collapsed; }   Looking through the code you’ll see that it checks to see if the Silverlight application is running out-of-browser and then either displays the WebBrowser control or runs the JavaScript function discussed earlier. Although the WebBrowser control’s Source property could be assigned the URI of the page to navigate to, by assigning HTML content using the NavigateToString() method and adding an iframe, content can be shown from any site including cross-domain sites. This is especially handy when you need to grab a page from a reporting site that’s in a different domain than the Silverlight application. Here’s an example of viewing  PDF file inside of an out-of-browser application. The first image shows the application running out-of-browser before the user clicks a PDF HyperlinkButton.  The second image shows the PDF being displayed.   While there are certainly other techniques that can be used, the ones shown here have worked well for us in different applications and provide the ability to display HTML content in-browser or out-of-browser. Feel free to add a comment if you have another tip or trick you like to use when working with HTML content in Silverlight applications.   Download Code Sample   For more information about onsite, online and video training, mentoring and consulting solutions for .NET, SharePoint or Silverlight please visit http://www.thewahlingroup.com.

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• A Taxonomy of Numerical Methods v1

  - by JoshReuben

  Numerical Analysis – When, What, (but not how) Once you understand the Math & know C++, Numerical Methods are basically blocks of iterative & conditional math code. I found the real trick was seeing the forest for the trees – knowing which method to use for which situation. Its pretty easy to get lost in the details – so I’ve tried to organize these methods in a way that I can quickly look this up. I’ve included links to detailed explanations and to C++ code examples. I’ve tried to classify Numerical methods in the following broad categories: Solving Systems of Linear Equations Solving Non-Linear Equations Iteratively Interpolation Curve Fitting Optimization Numerical Differentiation & Integration Solving ODEs Boundary Problems Solving EigenValue problems Enjoy – I did ! Solving Systems of Linear Equations Overview Solve sets of algebraic equations with x unknowns The set is commonly in matrix form Gauss-Jordan Elimination http://en.wikipedia.org/wiki/Gauss%E2%80%93Jordan_elimination C++: http://www.codekeep.net/snippets/623f1923-e03c-4636-8c92-c9dc7aa0d3c0.aspx Produces solution of the equations & the coefficient matrix Efficient, stable 2 steps: · Forward Elimination – matrix decomposition: reduce set to triangular form (0s below the diagonal) or row echelon form. If degenerate, then there is no solution · Backward Elimination –write the original matrix as the product of ints inverse matrix & its reduced row-echelon matrix à reduce set to row canonical form & use back-substitution to find the solution to the set Elementary ops for matrix decomposition: · Row multiplication · Row switching · Add multiples of rows to other rows Use pivoting to ensure rows are ordered for achieving triangular form LU Decomposition http://en.wikipedia.org/wiki/LU_decomposition C++: http://ganeshtiwaridotcomdotnp.blogspot.co.il/2009/12/c-c-code-lu-decomposition-for-solving.html Represent the matrix as a product of lower & upper triangular matrices A modified version of GJ Elimination Advantage – can easily apply forward & backward elimination to solve triangular matrices Techniques: · Doolittle Method – sets the L matrix diagonal to unity · Crout Method - sets the U matrix diagonal to unity Note: both the L & U matrices share the same unity diagonal & can be stored compactly in the same matrix Gauss-Seidel Iteration http://en.wikipedia.org/wiki/Gauss%E2%80%93Seidel_method C++: http://www.nr.com/forum/showthread.php?t=722 Transform the linear set of equations into a single equation & then use numerical integration (as integration formulas have Sums, it is implemented iteratively). an optimization of Gauss-Jacobi: 1.5 times faster, requires 0.25 iterations to achieve the same tolerance Solving Non-Linear Equations Iteratively find roots of polynomials – there may be 0, 1 or n solutions for an n order polynomial use iterative techniques Iterative methods · used when there are no known analytical techniques · Requires set functions to be continuous & differentiable · Requires an initial seed value – choice is critical to convergence à conduct multiple runs with different starting points & then select best result · Systematic - iterate until diminishing returns, tolerance or max iteration conditions are met · bracketing techniques will always yield convergent solutions, non-bracketing methods may fail to converge Incremental method if a nonlinear function has opposite signs at 2 ends of a small interval x1 & x2, then there is likely to be a solution in their interval – solutions are detected by evaluating a function over interval steps, for a change in sign, adjusting the step size dynamically. Limitations – can miss closely spaced solutions in large intervals, cannot detect degenerate (coinciding) solutions, limited to functions that cross the x-axis, gives false positives for singularities Fixed point method http://en.wikipedia.org/wiki/Fixed-point_iteration C++: http://books.google.co.il/books?id=weYj75E_t6MC&pg=PA79&lpg=PA79&dq=fixed+point+method++c%2B%2B&source=bl&ots=LQ-5P_taoC&sig=lENUUIYBK53tZtTwNfHLy5PEWDk&hl=en&sa=X&ei=wezDUPW1J5DptQaMsIHQCw&redir_esc=y#v=onepage&q=fixed%20point%20method%20%20c%2B%2B&f=false Algebraically rearrange a solution to isolate a variable then apply incremental method Bisection method http://en.wikipedia.org/wiki/Bisection_method C++: http://numericalcomputing.wordpress.com/category/algorithms/ Bracketed - Select an initial interval, keep bisecting it ad midpoint into sub-intervals and then apply incremental method on smaller & smaller intervals – zoom in Adv: unaffected by function gradient à reliable Disadv: slow convergence False Position Method http://en.wikipedia.org/wiki/False_position_method C++: http://www.dreamincode.net/forums/topic/126100-bisection-and-false-position-methods/ Bracketed - Select an initial interval , & use the relative value of function at interval end points to select next sub-intervals (estimate how far between the end points the solution might be & subdivide based on this) Newton-Raphson method http://en.wikipedia.org/wiki/Newton's_method C++: http://www-users.cselabs.umn.edu/classes/Summer-2012/csci1113/index.php?page=./newt3 Also known as Newton's method Convenient, efficient Not bracketed – only a single initial guess is required to start iteration – requires an analytical expression for the first derivative of the function as input. Evaluates the function & its derivative at each step. Can be extended to the Newton MutiRoot method for solving multiple roots Can be easily applied to an of n-coupled set of non-linear equations – conduct a Taylor Series expansion of a function, dropping terms of order n, rewrite as a Jacobian matrix of PDs & convert to simultaneous linear equations !!! Secant Method http://en.wikipedia.org/wiki/Secant_method C++: http://forum.vcoderz.com/showthread.php?p=205230 Unlike N-R, can estimate first derivative from an initial interval (does not require root to be bracketed) instead of inputting it Since derivative is approximated, may converge slower. Is fast in practice as it does not have to evaluate the derivative at each step. Similar implementation to False Positive method Birge-Vieta Method http://mat.iitm.ac.in/home/sryedida/public_html/caimna/transcendental/polynomial%20methods/bv%20method.html C++: http://books.google.co.il/books?id=cL1boM2uyQwC&pg=SA3-PA51&lpg=SA3-PA51&dq=Birge-Vieta+Method+c%2B%2B&source=bl&ots=QZmnDTK3rC&sig=BPNcHHbpR_DKVoZXrLi4nVXD-gg&hl=en&sa=X&ei=R-_DUK2iNIjzsgbE5ID4Dg&redir_esc=y#v=onepage&q=Birge-Vieta%20Method%20c%2B%2B&f=false combines Horner's method of polynomial evaluation (transforming into lesser degree polynomials that are more computationally efficient to process) with Newton-Raphson to provide a computational speed-up Interpolation Overview Construct new data points for as close as possible fit within range of a discrete set of known points (that were obtained via sampling, experimentation) Use Taylor Series Expansion of a function f(x) around a specific value for x Linear Interpolation http://en.wikipedia.org/wiki/Linear_interpolation C++: http://www.hamaluik.com/?p=289 Straight line between 2 points à concatenate interpolants between each pair of data points Bilinear Interpolation http://en.wikipedia.org/wiki/Bilinear_interpolation C++: http://supercomputingblog.com/graphics/coding-bilinear-interpolation/2/ Extension of the linear function for interpolating functions of 2 variables – perform linear interpolation first in 1 direction, then in another. Used in image processing – e.g. texture mapping filter. Uses 4 vertices to interpolate a value within a unit cell. Lagrange Interpolation http://en.wikipedia.org/wiki/Lagrange_polynomial C++: http://www.codecogs.com/code/maths/approximation/interpolation/lagrange.php For polynomials Requires recomputation for all terms for each distinct x value – can only be applied for small number of nodes Numerically unstable Barycentric Interpolation http://epubs.siam.org/doi/pdf/10.1137/S0036144502417715 C++: http://www.gamedev.net/topic/621445-barycentric-coordinates-c-code-check/ Rearrange the terms in the equation of the Legrange interpolation by defining weight functions that are independent of the interpolated value of x Newton Divided Difference Interpolation http://en.wikipedia.org/wiki/Newton_polynomial C++: http://jee-appy.blogspot.co.il/2011/12/newton-divided-difference-interpolation.html Hermite Divided Differences: Interpolation polynomial approximation for a given set of data points in the NR form - divided differences are used to approximately calculate the various differences. For a given set of 3 data points , fit a quadratic interpolant through the data Bracketed functions allow Newton divided differences to be calculated recursively Difference table Cubic Spline Interpolation http://en.wikipedia.org/wiki/Spline_interpolation C++: https://www.marcusbannerman.co.uk/index.php/home/latestarticles/42-articles/96-cubic-spline-class.html Spline is a piecewise polynomial Provides smoothness – for interpolations with significantly varying data Use weighted coefficients to bend the function to be smooth & its 1st & 2nd derivatives are continuous through the edge points in the interval Curve Fitting A generalization of interpolating whereby given data points may contain noise à the curve does not necessarily pass through all the points Least Squares Fit http://en.wikipedia.org/wiki/Least_squares C++: http://www.ccas.ru/mmes/educat/lab04k/02/least-squares.c Residual – difference between observed value & expected value Model function is often chosen as a linear combination of the specified functions Determines: A) The model instance in which the sum of squared residuals has the least value B) param values for which model best fits data Straight Line Fit Linear correlation between independent variable and dependent variable Linear Regression http://en.wikipedia.org/wiki/Linear_regression C++: http://www.oocities.org/david_swaim/cpp/linregc.htm Special case of statistically exact extrapolation Leverage least squares Given a basis function, the sum of the residuals is determined and the corresponding gradient equation is expressed as a set of normal linear equations in matrix form that can be solved (e.g. using LU Decomposition) Can be weighted - Drop the assumption that all errors have the same significance –-> confidence of accuracy is different for each data point. Fit the function closer to points with higher weights Polynomial Fit - use a polynomial basis function Moving Average http://en.wikipedia.org/wiki/Moving_average C++: http://www.codeproject.com/Articles/17860/A-Simple-Moving-Average-Algorithm Used for smoothing (cancel fluctuations to highlight longer-term trends & cycles), time series data analysis, signal processing filters Replace each data point with average of neighbors. Can be simple (SMA), weighted (WMA), exponential (EMA). Lags behind latest data points – extra weight can be given to more recent data points. Weights can decrease arithmetically or exponentially according to distance from point. Parameters: smoothing factor, period, weight basis Optimization Overview Given function with multiple variables, find Min (or max by minimizing –f(x)) Iterative approach Efficient, but not necessarily reliable Conditions: noisy data, constraints, non-linear models Detection via sign of first derivative - Derivative of saddle points will be 0 Local minima Bisection method Similar method for finding a root for a non-linear equation Start with an interval that contains a minimum Golden Search method http://en.wikipedia.org/wiki/Golden_section_search C++: http://www.codecogs.com/code/maths/optimization/golden.php Bisect intervals according to golden ratio 0.618.. Achieves reduction by evaluating a single function instead of 2 Newton-Raphson Method Brent method http://en.wikipedia.org/wiki/Brent's_method C++: http://people.sc.fsu.edu/~jburkardt/cpp_src/brent/brent.cpp Based on quadratic or parabolic interpolation – if the function is smooth & parabolic near to the minimum, then a parabola fitted through any 3 points should approximate the minima – fails when the 3 points are collinear , in which case the denominator is 0 Simplex Method http://en.wikipedia.org/wiki/Simplex_algorithm C++: http://www.codeguru.com/cpp/article.php/c17505/Simplex-Optimization-Algorithm-and-Implemetation-in-C-Programming.htm Find the global minima of any multi-variable function Direct search – no derivatives required At each step it maintains a non-degenerative simplex – a convex hull of n+1 vertices. Obtains the minimum for a function with n variables by evaluating the function at n-1 points, iteratively replacing the point of worst result with the point of best result, shrinking the multidimensional simplex around the best point. Point replacement involves expanding & contracting the simplex near the worst value point to determine a better replacement point Oscillation can be avoided by choosing the 2nd worst result Restart if it gets stuck Parameters: contraction & expansion factors Simulated Annealing http://en.wikipedia.org/wiki/Simulated_annealing C++: http://code.google.com/p/cppsimulatedannealing/ Analogy to heating & cooling metal to strengthen its structure Stochastic method – apply random permutation search for global minima - Avoid entrapment in local minima via hill climbing Heating schedule - Annealing schedule params: temperature, iterations at each temp, temperature delta Cooling schedule – can be linear, step-wise or exponential Differential Evolution http://en.wikipedia.org/wiki/Differential_evolution C++: http://www.amichel.com/de/doc/html/ More advanced stochastic methods analogous to biological processes: Genetic algorithms, evolution strategies Parallel direct search method against multiple discrete or continuous variables Initial population of variable vectors chosen randomly – if weighted difference vector of 2 vectors yields a lower objective function value then it replaces the comparison vector Many params: #parents, #variables, step size, crossover constant etc Convergence is slow – many more function evaluations than simulated annealing Numerical Differentiation Overview 2 approaches to finite difference methods: · A) approximate function via polynomial interpolation then differentiate · B) Taylor series approximation – additionally provides error estimate Finite Difference methods http://en.wikipedia.org/wiki/Finite_difference_method C++: http://www.wpi.edu/Pubs/ETD/Available/etd-051807-164436/unrestricted/EAMPADU.pdf Find differences between high order derivative values - Approximate differential equations by finite differences at evenly spaced data points Based on forward & backward Taylor series expansion of f(x) about x plus or minus multiples of delta h. Forward / backward difference - the sums of the series contains even derivatives and the difference of the series contains odd derivatives – coupled equations that can be solved. Provide an approximation of the derivative within a O(h^2) accuracy There is also central difference & extended central difference which has a O(h^4) accuracy Richardson Extrapolation http://en.wikipedia.org/wiki/Richardson_extrapolation C++: http://mathscoding.blogspot.co.il/2012/02/introduction-richardson-extrapolation.html A sequence acceleration method applied to finite differences Fast convergence, high accuracy O(h^4) Derivatives via Interpolation Cannot apply Finite Difference method to discrete data points at uneven intervals – so need to approximate the derivative of f(x) using the derivative of the interpolant via 3 point Lagrange Interpolation Note: the higher the order of the derivative, the lower the approximation precision Numerical Integration Estimate finite & infinite integrals of functions More accurate procedure than numerical differentiation Use when it is not possible to obtain an integral of a function analytically or when the function is not given, only the data points are Newton Cotes Methods http://en.wikipedia.org/wiki/Newton%E2%80%93Cotes_formulas C++: http://www.siafoo.net/snippet/324 For equally spaced data points Computationally easy – based on local interpolation of n rectangular strip areas that is piecewise fitted to a polynomial to get the sum total area Evaluate the integrand at n+1 evenly spaced points – approximate definite integral by Sum Weights are derived from Lagrange Basis polynomials Leverage Trapezoidal Rule for default 2nd formulas, Simpson 1/3 Rule for substituting 3 point formulas, Simpson 3/8 Rule for 4 point formulas. For 4 point formulas use Bodes Rule. Higher orders obtain more accurate results Trapezoidal Rule uses simple area, Simpsons Rule replaces the integrand f(x) with a quadratic polynomial p(x) that uses the same values as f(x) for its end points, but adds a midpoint Romberg Integration http://en.wikipedia.org/wiki/Romberg's_method C++: http://code.google.com/p/romberg-integration/downloads/detail?name=romberg.cpp&can=2&q= Combines trapezoidal rule with Richardson Extrapolation Evaluates the integrand at equally spaced points The integrand must have continuous derivatives Each R(n,m) extrapolation uses a higher order integrand polynomial replacement rule (zeroth starts with trapezoidal) à a lower triangular matrix set of equation coefficients where the bottom right term has the most accurate approximation. The process continues until the difference between 2 successive diagonal terms becomes sufficiently small. Gaussian Quadrature http://en.wikipedia.org/wiki/Gaussian_quadrature C++: http://www.alglib.net/integration/gaussianquadratures.php Data points are chosen to yield best possible accuracy – requires fewer evaluations Ability to handle singularities, functions that are difficult to evaluate The integrand can include a weighting function determined by a set of orthogonal polynomials. Points & weights are selected so that the integrand yields the exact integral if f(x) is a polynomial of degree <= 2n+1 Techniques (basically different weighting functions): · Gauss-Legendre Integration w(x)=1 · Gauss-Laguerre Integration w(x)=e^-x · Gauss-Hermite Integration w(x)=e^-x^2 · Gauss-Chebyshev Integration w(x)= 1 / Sqrt(1-x^2) Solving ODEs Use when high order differential equations cannot be solved analytically Evaluated under boundary conditions RK for systems – a high order differential equation can always be transformed into a coupled first order system of equations Euler method http://en.wikipedia.org/wiki/Euler_method C++: http://rosettacode.org/wiki/Euler_method First order Runge–Kutta method. Simple recursive method – given an initial value, calculate derivative deltas. Unstable & not very accurate (O(h) error) – not used in practice A first-order method - the local error (truncation error per step) is proportional to the square of the step size, and the global error (error at a given time) is proportional to the step size In evolving solution between data points xn & xn+1, only evaluates derivatives at beginning of interval xn à asymmetric at boundaries Higher order Runge Kutta http://en.wikipedia.org/wiki/Runge%E2%80%93Kutta_methods C++: http://www.dreamincode.net/code/snippet1441.htm 2nd & 4th order RK - Introduces parameterized midpoints for more symmetric solutions à accuracy at higher computational cost Adaptive RK – RK-Fehlberg – estimate the truncation at each integration step & automatically adjust the step size to keep error within prescribed limits. At each step 2 approximations are compared – if in disagreement to a specific accuracy, the step size is reduced Boundary Value Problems Where solution of differential equations are located at 2 different values of the independent variable x à more difficult, because cannot just start at point of initial value – there may not be enough starting conditions available at the end points to produce a unique solution An n-order equation will require n boundary conditions – need to determine the missing n-1 conditions which cause the given conditions at the other boundary to be satisfied Shooting Method http://en.wikipedia.org/wiki/Shooting_method C++: http://ganeshtiwaridotcomdotnp.blogspot.co.il/2009/12/c-c-code-shooting-method-for-solving.html Iteratively guess the missing values for one end & integrate, then inspect the discrepancy with the boundary values of the other end to adjust the estimate Given the starting boundary values u1 & u2 which contain the root u, solve u given the false position method (solving the differential equation as an initial value problem via 4th order RK), then use u to solve the differential equations. Finite Difference Method For linear & non-linear systems Higher order derivatives require more computational steps – some combinations for boundary conditions may not work though Improve the accuracy by increasing the number of mesh points Solving EigenValue Problems An eigenvalue can substitute a matrix when doing matrix multiplication à convert matrix multiplication into a polynomial EigenValue For a given set of equations in matrix form, determine what are the solution eigenvalue & eigenvectors Similar Matrices - have same eigenvalues. Use orthogonal similarity transforms to reduce a matrix to diagonal form from which eigenvalue(s) & eigenvectors can be computed iteratively Jacobi method http://en.wikipedia.org/wiki/Jacobi_method C++: http://people.sc.fsu.edu/~jburkardt/classes/acs2_2008/openmp/jacobi/jacobi.html Robust but Computationally intense – use for small matrices < 10x10 Power Iteration http://en.wikipedia.org/wiki/Power_iteration For any given real symmetric matrix, generate the largest single eigenvalue & its eigenvectors Simplest method – does not compute matrix decomposition à suitable for large, sparse matrices Inverse Iteration Variation of power iteration method – generates the smallest eigenvalue from the inverse matrix Rayleigh Method http://en.wikipedia.org/wiki/Rayleigh's_method_of_dimensional_analysis Variation of power iteration method Rayleigh Quotient Method Variation of inverse iteration method Matrix Tri-diagonalization Method Use householder algorithm to reduce an NxN symmetric matrix to a tridiagonal real symmetric matrix vua N-2 orthogonal transforms     Whats Next Outside of Numerical Methods there are lots of different types of algorithms that I’ve learned over the decades: Data Mining – (I covered this briefly in a previous post: http://geekswithblogs.net/JoshReuben/archive/2007/12/31/ssas-dm-algorithms.aspx ) Search & Sort Routing Problem Solving Logical Theorem Proving Planning Probabilistic Reasoning Machine Learning Solvers (eg MIP) Bioinformatics (Sequence Alignment, Protein Folding) Quant Finance (I read Wilmott’s books – interesting) Sooner or later, I’ll cover the above topics as well.

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• What sources do spammers use to get email addresses?

  - by Andrew Grimm

  From what sources do email spammers get their addresses? Wikipedia mentions the following: Harvesting email addresses from publicly available sources. This includes web pages (web crawling), usenet posts, mailing list archives, DNS and WHOIS records Guessing email addresses (directory harvest attack) Asking people for their emails for one purpose, such as jokes of the day, and selling the email addresses elsewhere Getting access to people's address books (which Quechup utilized) Scanning an infected computer for email addresses. Are there any other techniques used? Are any of the techniques above now obsolete?

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• Deprecated Methods in Code Base

  - by Jamie Taylor

  A lot of the code I've been working on recently, both professionally (read: at work) and in other spheres (read: at home, for friends/family/etc, or NOT FOR WORK), has been worked on, redesigned and re-implemented several times - where possible/required. This has been in an effort to make things smaller, faster more efficient, better and closer to spec (when requirements have changed). A down side to this is that I now have several code bases that have deprecated method blocks (and in some places small objects). I'm looking at making this code maintainable and easy to roll back on changes. I'm already using version control software in both instances, but I'm left wondering if there are any specific techniques that have been used by others for keeping the superseded methods without increasing the size of compiled outputs? At the minute, I'm simply wrapping the old code in C style multi line comments. Here's an example of what I mean (C style, psuedo-code): void main () { //Do some work //Foo(); //Deprecated method call Bar(); //New method } /***** Deprecated code ***** /// Summary of Method void Foo() { //Do some work } ***** Deprecated Code *****/ /// Summary of method void Bar() { //Do some work } I've added a C style example, simply because I'm more confident with the C style languages. I'm trying to put this question across as language agnostic (hence the tag), and would prefer language agnostic answers, if possible - since I see this question as more of a techniques and design question. I'd like to keep the old methods and blocks for a bunch of reasons, chief amongst them being the ability to quickly restore an older working method in the case of some tests failing, or some unforeseen circumstance. Is there a better way to do this (that multi line comments)? Are there any tools that will allow me to store these old methods in separate files? Is that even a good idea?

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• 2.5D game development

  - by ne5tebiu

  2.5D ("two-and-a-half-dimensional"), 3/4 perspective and pseudo-3D are terms used to describe either: graphical projections and techniques which cause a series of images or scenes to fake or appear to be three-dimensional (3D) when in fact they are not, or gameplay in an otherwise three-dimensional video game that is restricted to a two-dimensional plane. (Information taken from Wikipedia.org) I have a question based on 2.5D game development. As stated before, 2.5D uses graphical projections and techniques to make fake 3d or a gameplay restricted to a two-dimensional plane. A good example is a TQ Digital made game: Zero Online (screenshot) the whole map is made of 2d images and only NPCs and players are 3d. The maps were drawn manually by hand without any 3d software rendering. As I'm playing the game I feel like I'm going from a lower part of the map (ground) to a higher one (some metal platform) and it feels like I'm moving in 3 dimensions. But when I look closely, I see that the player size didn't change and the shadow too but I'm still feeling like I'm somehow higher then before (I had rendered a simple map myself that I made in 3dmax but it didn't quite give the result I wanted). How to accomplish such an effect?

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• New PeopleTools Developer Book Available

  - by matthew.haavisto

  I recently had an opportunity to work through a copy of a new book for PeopleTools developers and thought it might be of interest to the readers of the PeopleTools blog. It is called PeopleSoft PeopleTools Tips & Techniques, and was written by Jim Marion, a long-time Oracle employee we often recruit to deliver the very popular and highly regarded conference sessions of the same title. This book is not for the beginner and doesn't contain much introductory material. Instead, it's for the more experienced PeopleSoft developer looking to maximize the efficiency and productivity of their PeopleSoft applications. Throughout the book Jim offers proven methods and best practices he's worked with personally. PeopleSoft PeopleTools Tips & Techniques lays out the benefits of many tactics along with implementation considerations, programming instructions, and reusable code samples. It will help you construct powerful iScripts, build custom UIs, work with Java and Ajax, and integrate the latest Web 2.0 features. Test-driven development, application security, performance tuning, and debugging are also covered in this authoritative resource. This book was one of the best sellers at the Oracle bookstore during the most recent Oracle Open World conference. The book can be ordered here and here. You may also want to check out Jim's PeopleTools developer blog.

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• Monster's AI in an Action-RPG

  - by Andrea Tucci

  I'm developing an action rpg with some University colleagues. We've gotton to the monsters' AI design and we would like to implement a sort of "utility-based AI" so we have a "thinker" that assigns a numeric value on all the monster's decisions and we choose the highest (or the most appropriate, depending on monster's iq) and assign it in the monster's collection of decisions (like a goal-driven design pattern) . One solution we found is to write a mathematical formula for each decision, with all the important parameters for evaluation (so for a spell-decision we might have mp,distance from player, player's hp etc). This formula also has coefficients representing some of monster's behaviour (in this way we can alterate formulas by changing coefficients). I've also read how "fuzzy logic" works; I was fascinated by it and by the many ways of expansion it has. I was wondering how we could use this technique to give our AI more semplicity, as in create evaluations with fuzzy rules such as IF player_far AND mp_high AND hp_high THEN very_Desiderable (for a spell having an high casting-time and consume high mp) and then 'defuzz' it. In this way it's also simple to create a monster behaviour by creating ad-hoc rules for every monster's IQ category. But is it correct using fuzzy logic in a game with many parameters like an rpg? Is there a way of merging these two techniques? Are there better AI design techniques for evaluating monster's chooses?

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• Can defect containment metrics be readily applied at an organizational level when there is only a consistant organizational process framework?

  - by Thomas Owens

  Defect containment metrics, such as total defect containment effectiveness (TDCE) and phase containment effectiveness (PCE), can be used to give a good indicator of the quality of the process. TDCE captures the defects that are captured at some point between requirements and the release of a product into the field, indicating the overall effectiveness of the entire process to find and remove defects. PCE provides more detail at each phase of the software development life cycle and how the defect detection and removal techniques are working. Applying these metrics makes sense at a level where you have a well-defined process and methodology for product development, often a project. However, some organizations provide a process framework that is tailored at the project level. This process framework would include the necessary guidance for meeting certifications (ISO9001, CMMI), practices for incorporating known good techniques (agile methods, Lean, Six Sigma), and requirements for legal or regulatory reasons. However, the specific details of how to gather requirements, design the system, produce the software, conduct test, and release are left to the product development teams. Is there any effective way to apply defect containment metrics at an organizational level when only a process framework exists at the organizational level? If not, what might be some ideas for metrics that can be distilled from each project (each using a tailored process that fits into the organizational process framework) that captures defect containment metrics to discuss the ability of the process to find and remove defects? The end goal of such a metric would be to consolidate the defect containment practices of a large number of ongoing projects and report to management. The target audience would be people in roles such as the chief software engineer and the chief engineer (of all engineering disciplines) for the organization. Although project specific data would be available, the idea is to produce something that quantifies the general effectiveness of all tailored processes across all ongoing projects. I would suspect that this data would also be presented as part of CMMI, ISO, or similar audits to demonstrate process quality.

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• Project Corndog: Viva el caliente perro!

  - by Matt Christian

  During one of my last semesters in college we were required to take a class call Computer Graphics which tried (quite unsuccessfully) to teach us a combination of mathematics, OpenGL, and 3D rendering techniques.  The class itself was horrible, but one little gem of an idea came out of it.  See, the final project in the class was to team up and create some kind of demo or game using techniques we learned in class.  My friend Paul and I teamed up and developed a top down shooter that, given the stringent timeline, was much less of a game and much more of 3D objects floating around a screen. The idea itself however I found clever and unique and decided it was time to spend some time developing a proper version of our idea.  Project Corndog as it is tentatively named, pits you as a freshly fried corndog who broke free from the shackles of fair food slavery in a quest to escape the state fair you were born in.  Obviously it's quite a serious game with undertones of racial prejudice, immoral practices, and cheap food sold at high prices. The game itself is a top down shooter in the style of 1942 (NES).  As a delicious corndog you will have to fight through numerous enemies including hungry babies, carnies, and the corndog serial-killer himself the corndog eating champion!  Other more engaging and frighteningly realistic enemies await as the only thing between you and freedom. Project Corndog is being developed in Visual Studio 2008 with XNA Game Studio 3.1.  It is currently being hosted on Google code and will be made available as an open source engine in the coming months.

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• Here's your chance: MOS Feedback Sessions @OOW

  - by cwarticki

  Bring your questions, comments, concerns, opinions, recommendations, enhancement requests and any emotional outbursts!   As I travel the world and speak to thousands of customers, I receive plenty of feedback about My Oracle support.  Come hear directly from the source. Meet Dennis Reno, VP of Customer Portal Experience. The Customer Portal Experience team will host a My Oracle Support Tips and Techniques session and three roundtable feedback sessions at this year’s Oracle OpenWorld. The sessions will include a Hardware Support component, as well as best practices that are sure to benefit all My Oracle Support users. The events planned will give our users the opportunity to learn more about how the My Oracle Support customer portal adds value to the support process and to their business needs. The roundtable feedback sessions will allow customers to meet, give feedback, and share their experiences directly with the team responsible for the customer portal experience. Date Time (PT) Session Name Mon, Oct 1 01:45 PM My Oracle Support: Tips and Techniques for Getting the Best Hardware Support Possible (Session #CON9745) Tue, Oct 2 11:00 AM Roundtable - My Oracle Support General Feedback Wed, Oct 3 11:00 AM Roundtable - My Oracle Support Community Feedback Thr, Oct 4 11:00 AM Roundtable - My Oracle Support General Feedback Customers can find more information, including specific details about how to attend, by accessing My Oracle Support at OpenWorld (Article ID 1484508.1). Enjoy OpenWorld everyone! -Chris Warticki Global Customer Management

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• Optimizing lifestyle and training

  - by Gabe

  I am a college freshman who has recently discovered a passion for computer science. Having had my first lick of formal python training last semester, I have cast aside my previously hedonist way of life and tunneled my sights on becoming the most rounded and proficient programmer I can be. I know that I'm taking strides in the right direction (I've stopped smoking, I've been exercising every day, I've taught myself C++ and OpenGL, and I've begun training in kung-fu and meditation), yet I am still finding myself struggling to achieve satisfactory results. I would like to be able to spend a good 3-4 hours every day burning through textbooks. I have the time cleared and the resources allocated. The problem lies in the logistics-- I have never taken anything seriously before. Recently I've realized that I am clueless when it comes to taking care of myself and gaining control of my mind, and it drastically hinders my productivity. My question is this: How can I learn to manage my time and take care of myself such that I can spend the maximum amount of time every day studying with steady concentration? Personal tricks would be key here: techniques you use to get yourself to sleep, a diet that yields focus, even computer break stretching routines or active reading techniques. Anything you could think of here would be great. I was a low-life in high school and I have the drive to turn my life around, I'm just quite a bit behind in the way of good habits :)

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• Checking All Checkboxes in a GridView Using jQuery

  In May 2006 I wrote two articles that showed how to add a column of checkboxes to a GridView and offer the ability for users to check (or uncheck) all checkboxes in the column with a single click of the mouse. The first article, Checking All CheckBoxes in a GridView, showed how to add "Check All" and "Uncheck All" buttons to the page above the GridView that, when clicked, checked or unchecked all of the checkboxes. The second article, Checking All CheckBoxes in a GridView Using Client-Side Script and a Check All CheckBox, detailed how to add a checkbox to the checkbox column in the grid's header row that would check or uncheck all checkboxes in the column. Both articles showed how to implement such functionality on the client-side, thereby removing the need for a postback. The JavaScript presented in these two previous articles still works, but the techniques used are a bit antiquated and hamfisted given the advances made in JavaScript programming over the past few years. For instance, the script presented in the previous articles uses server-side code in the GridView's DataBound event handler to assign a client-side onclick event handler to each checkbox. While this works, it violates the tenets of unobtrusive JavaScript, which is a design guideline for JavaScript programming that encourages a clean separation of functionality from presentation. (Ideally, event handlers for HTML elements are defined in script.) Also, the quantity of JavaScript used in the two previous articles is quite hefty compared to the amount of code that would be needed using modern JavaScript libraries like jQuery. This article presents updated JavaScript for checking (and unchecking) all checkboxes within a GridView. The two examples from the previous articles - checking/unchecking all checkboxes using a button and checking/unchecking all checkboxes using a checkbox in the header row - are reimplemented here using jQuery and unobtrusive JavaScript techniques. Read on to learn more! Read More >

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• Clipping polygons in XNA with stencil (not using spritebatch)

  - by Blau

  The problem... i'm drawing polygons, in this case boxes, and i want clip children polygons with its parent's client area. // Class Region public void Render(GraphicsDevice Device, Camera Camera) { int StencilLevel = 0; Device.Clear( ClearOptions.Stencil, Vector4.Zero, 0, StencilLevel ); Render( Device, Camera, StencilLevel ); } private void Render(GraphicsDevice Device, Camera Camera, int StencilLevel) { Device.SamplerStates[0] = this.SamplerState; Device.Textures[0] = this.Texture; Device.RasterizerState = RasterizerState.CullNone; Device.BlendState = BlendState.AlphaBlend; Device.DepthStencilState = DepthStencilState.Default; Effect.Prepare(this, Camera ); Device.DepthStencilState = GlobalContext.GraphicsStates.IncMask; Device.ReferenceStencil = StencilLevel; foreach ( EffectPass pass in Effect.Techniques[Technique].Passes ) { pass.Apply( ); Device.DrawUserIndexedPrimitives<VertexPositionColorTexture>( PrimitiveType.TriangleList, VertexData, 0, VertexData.Length, IndexData, 0, PrimitiveCount ); } foreach ( Region child in ChildrenRegions ) { child.Render( Device, Camera, StencilLevel + 1 ); } Effect.Prepare( this, Camera ); // This does not works Device.BlendState = GlobalContext.GraphicsStates.NoWriteColor; Device.DepthStencilState = GlobalContext.GraphicsStates.DecMask; Device.ReferenceStencil = StencilLevel; // This should be +1, but in that case the last drrawed is blue and overlap all foreach ( EffectPass pass in Effect.Techniques[Technique].Passes ) { pass.Apply( ); Device.DrawUserIndexedPrimitives<VertexPositionColorTexture>( PrimitiveType.TriangleList, VertexData, 0, VertexData.Length, IndexData, 0, PrimitiveCount ); } } public static class GraphicsStates { public static BlendState NoWriteColor = new BlendState( ) { ColorSourceBlend = Blend.One, AlphaSourceBlend = Blend.One, ColorDestinationBlend = Blend.InverseSourceAlpha, AlphaDestinationBlend = Blend.InverseSourceAlpha, ColorWriteChannels1 = ColorWriteChannels.None }; public static DepthStencilState IncMask = new DepthStencilState( ) { StencilEnable = true, StencilFunction = CompareFunction.Equal, StencilPass = StencilOperation.IncrementSaturation, }; public static DepthStencilState DecMask = new DepthStencilState( ) { StencilEnable = true, StencilFunction = CompareFunction.Equal, StencilPass = StencilOperation.DecrementSaturation, }; } How can achieve this? EDIT: I've just relized that the NoWriteColors.ColorWriteChannels1 should be NoWriteColors.ColorWriteChannels. :) Now it's clipping right. Any other approach?

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• jQuery Samples

  - by dwahlin

  Here are the jsfiddle samples that John Papa and I covered in our jQuery Fundamentals workshop at DevConnections last week. These were a few of the samples we wrote on the fly (so they’re not “perfect”) using http://jsfiddle.net and wanted to share. Additional jQuery samples covering selectors, DOM manipulation, Ajax techniques, as well as sample applications can be found here. You can also view the talks John gave at the conference here.  Code and slides from my talks can be found at the following links: Building the Account at a Glance ASP.NET MVC, EF Code First, HTML5, and jQuery Application Techniques, Strategies, and Patterns for Structuring JavaScript Code Getting Started Building Windows 8 HTML/JavaScript Metro Apps If you’re interested in learning more about jQuery check out my jQuery Fundamentals course at Pluralsight.com. Using the Data Function   Using Object Literals with jQuery   Using jQuery each() with string concatenation   Using on() to handle child events   jQuery - hover   jQuery - event handling variations   jQuery - Twitter (bind, append, appendTo, each, fadeOut, $.getJSON, callback, success, error, complete)r   jQuery - attr vs prop   jQuery - Simple selectors

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