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• C++ Numerical Recipes &ndash; A New Adventure!

  - by JoshReuben

  I am about to embark on a great journey – over the next 6 weeks I plan to read through C++ Numerical Recipes 3rd edition http://amzn.to/YtdpkS I'll be reading this with an eye to C++ AMP, thinking about implementing the suitable subset (non-recursive, additive, commutative) to run on the GPU. APIs supporting HPC, GPGPU or MapReduce are all useful – providing you have the ability to choose the correct algorithm to leverage on them. I really think this is the most fascinating area of programming – a lot more exciting than LOB CRUD !!! When you think about it , everything is a function – we categorize & we extrapolate. As abstractions get higher & less leaky, sooner or later information systems programming will become a non-programmer task – you will be using WYSIWYG designers to build: GUIs MVVM service mapping & virtualization workflows ORM Entity relations In the data source SharePoint / LightSwitch are not there yet, but every iteration gets closer. For information workers, managed code is a race to the bottom. As MS futures are a bit shaky right now, the provider agnostic nature & higher barriers of entry of both C++ & Numerical Analysis seem like a rational choice to me. Its also fascinating – stepping outside the box. This is not the first time I've delved into numerical analysis. 6 months ago I read Numerical methods with Applications, which can be found for free online: http://nm.mathforcollege.com/ 2 years ago I learned the .NET Extreme Optimization library www.extremeoptimization.com – not bad 2.5 years ago I read Schaums Numerical Analysis book http://amzn.to/V5yuLI - not an easy read, as topics jump back & forth across chapters: 3 years ago I read Practical Numerical Methods with C# http://amzn.to/V5yCL9 (which is a toy learning language for this kind of stuff) I also read through AI a Modern Approach 3rd edition END to END http://amzn.to/V5yQSp - this took me a few years but was the most rewarding experience. I'll post progress updates – see you on the other side !

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• Little mysterious RowMatch

  - by kishore.kondepudi(at)oracle.com

  Incidentally this was the first piece of code i ever wrote in ADF.The requirement was we have tax rates which are read from a table.And there can be different type of tax rates called certificates or exceptions based on the rate_type column in the tax rates table.The simplest design i chose was to create an EO on the tax rates table and create two VO's called CertificateVO and ExceptionVO based on the same EO.So far so good.I wrote all the business logic in the EO and completed the model project.The CertificateVO has the query as select * from tax_rates TaxRateEO where rate_type='CERTIFICATE' and similary the ExceptionVO is also built.The UI is pretty simple and it has two tabs called Certificates and Exceptions and each table has a button to create a tax rate.The certificate tab is driven by CertificateVO and exception tab is driven by ExceptionVO.The CertificateVO has default value of rate_type set to 'CERTIFICATE' and ExceptionVO has default value of rate_type to 'EXCEPTION' to default values for new records.So far so good.But on running the UI i noticed a strange thing,When i create a new row in Certificate i see the same row in Exception too and vice-versa.i.e; what ever row i create in one VO it also appears in the second one although it shouldn't be.I couldn't understand the reason for behavior even though an explicit where clause is present.Digging through documentation i found that ADF doesnt apply the where clause to new rows instead it applies something called as RowMatch to them.RowMatch in simple terms is a where condition applied to the VO rows at runtime.Since we had both VO's based on the same EO we have the same entity cache.The filter factor for new rows to be shown in VO at runtime is actually RowMatch than the where clause defined in the VO.The default RowMatch is empty as a result any new row appears in both the VO's since its from same entity cache.The solution to this problem is to use polymorphic view objects which can do the row filter based on configuration or override the getRowMatch() method in the VOImpl and pass the custom where filter instead of default RowMatch.Eg:@Overridepublic RowMatch getRowMatch(){    return new RowMatch("rate_type='CERTIFICATE'");}similarly for ExceptionVO too.With proper RowMatch in place new rows will route themselves to appropriate VO.PS: The behavior(Same row pushed to both VO's from entity cache) is also called as ViewLink Consistency.Try it out!

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• What You Said: Where Do You Find Your Next Game?

  - by Jason Fitzpatrick

  Earlier this week we asked you to share your favorite places and tricks for finding new video games to play. It turns out the least of your problems was finding new games! From the comments it became apparent How-To Geek readers had absolutely no problem finding new games to add to their gaming stable. Buzz writes: I have quite an elaborate procedure in finding my next game:For free games i simply follow the feeds on a few websites like Freegamer, LinuxGames, HappyPenguin and Penguspy. Every now and them i browse Wikipedia articles on free/FOSS games. For commercial games the procedure depends on what i enjoyed the most in that game:- If i enjoyed the story or the general feel: i usually start with a game i like and look for sequels, prequels, mods or spinoffs. I even go out on a limb and give other platforms (than a PC) a try, even if it usually means emulation. If you really enjoy a game series/saga it’s usually worth the effort.- If i enjoy the producer/gaming company then i seek out more of their games.- If i enjoy the technical achievements that went into making the game or if i am concerned for the system requirements of my gear i try to play games that are built on the same engine(s) as one of the games i ran smooth and enjoyed.- If i feel like playing a particular genre i usually start with a title i enjoyed and look for alternatives or similar games- You can always try searching for Game of The Year winners for a particular time period or other similar accomplishments. They usually yield great results. How to Make Your Laptop Choose a Wired Connection Instead of Wireless HTG Explains: What Is Two-Factor Authentication and Should I Be Using It? HTG Explains: What Is Windows RT and What Does It Mean To Me?

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• CodePlex Daily Summary for Saturday, February 26, 2011

  CodePlex Daily Summary for Saturday, February 26, 2011Popular ReleasesDirectQ: Release 1.8.7 Beta 2: Beta 2 release to fix some early reported problems with the original 1.8.7 Beta.Chiave File Encryption: Chiave 0.9.2: Release Notes Application for file encryption and decryption using 512 Bit rijndael encyrption algorithm with simple to use UI. Its written in C# and compiled in .Net version 3.5. It incorporates features of Windows 7 like Jumplists, Taskbar progress and Aero Glass. Now with added support to Windows XP! Change Log from 0.9.1 to 0.9.2: ==================== Added: > Now it displays number of files added in the wizard to the Window Title bar. > Added support to Windows XP. > Minor UI tweaks. I...Claims Based Identity & Access Control Guide: Drop 1 - Claims Identity Guide V2: Highlights of drop #1 This is the first drop of the new "Claims Identity Guide" edition. In this release you will find: All previous samples updated and enhanced. All code upgraded to .NET 4 and Visual Studio 2010. Extensive cleanup. Refactored Simulated Issuers: each solution now gets its own issuers. This results in much cleaner and simpler to understand code. Added Single Sign Out support. Added first sample using ACS ("ACS as a Federation Provider"). This sample extends the ori...HFR7 - Forum Hardware.fr pour Windows Phone 7: HFR7 - v1.1.1: NOUVELLES FONCTIONS : - Aucune. AMÉLIORATIONS : - La page "Catégories" est désormais intégrée au pivot "Bienvenue". - Apparition de boutons de changement de page en bas du sujet en consultation. - Les en-têtes sur les sujets sont désormais de la même couleur que la couleur d'accentuation de votre téléphone. BUGFIXES : - Les catégories s'affichent correctement. - Cliquer sur le bouton "drapeau" alors qu'on est dans la liste des topics d'une page n'amenait pas directement au dernier post non ...Simple Notify: Simple Notify Beta 2011-02-25: Feature: host the service with a single click in console Feature: host the service as a windows service Feature: notification cient application Feature: push client application Feature: push notifications from your powershell script Feature: C# wrapper libraries for your applicationsMono.Addins: Mono.Addins 0.6: The 0.6 release of Mono.Addins includes many improvements, bug fixes and new features: Add-in engine Add-in name and description can now be localized. There are new custom attributes for defining them, and can also be specified as xml elements in an add-in manifest instead of attributes. Support for custom add-in properties. It is now possible to specify arbitrary properties in add-ins, which can be queried at install time (using the Mono.Addins.Setup API) or at run-time. Custom extensio...patterns & practices: Project Silk: Project Silk Community Drop 3 - 25 Feb 2011: IntroductionWelcome to the third community drop of Project Silk. For this drop we are requesting feedback on overall application architecture, code review of the JavaScript Conductor and Widgets, and general direction of the application. Project Silk provides guidance and sample implementations that describe and illustrate recommended practices for building modern web applications using technologies such as HTML5, jQuery, CSS3 and Internet Explorer 9. This guidance is intended for experien...PhoneyTools: Initial Release (0.1): This is the 0.1 version for preview of the features.Minemapper: Minemapper v0.1.5: Now supports new Minecraft beta v1.3 map format, thanks to updated mcmap. Disabled biomes, until Minecraft Biome Extractor supports new format.Smartkernel: Smartkernel: ????，??????Coding4Fun Tools: Coding4Fun.Phone.Toolkit v1.2: New control, Toast Prompt! Removed progress bar since Silverlight Toolkit Feb 2010 has it.Umbraco CMS: Umbraco 4.7: Service release fixing 31 issues. A full changelog will be available with the final stable release of 4.7 Important when upgradingUpgrade as if it was a patch release (update /bin, /umbraco and /umbraco_client). For general upgrade information follow the guide found at http://our.umbraco.org/wiki/install-and-setup/upgrading-an-umbraco-installation 4.7 requires the .NET 4.0 framework Web.Config changes Update the web web.config to include the 4 changes found in (they're clearly marked in...HubbleDotNet - Open source full-text search engine: V1.1.0.0: Add Sqlite3 DBAdapter Add App Report when Query Cache is Collecting. Improve the performance of index through Synchronize. Add top 0 feature so that we can only get count of the result. Improve the score calculating algorithm of match. Let the score of the record that match all items large then others. Add MySql DBAdapter Improve performance for multi-fields sort . Using hash table to access the Payload data. The version before used bin search. Using heap sort instead of qui...Silverlight????[???]: silverlight????[???]2.0: ???????，?????，????????silverlight??????。DBSourceTools: DBSourceTools_1.3.0.0: Release 1.3.0.0 Changed editors from FireEdit to ICSharpCode.TextEditor. Complete re-vamp of Intellisense ( further testing needed). Hightlight Field and Table Names in sql scripts. Added field dropdown on all tables and views in DBExplorer. Added data option for viewing data in Tables. Fixed comment / uncomment bug as reported by tareq. Included Synonyms in scripting engine ( nickt_ch ).IronPython: 2.7 Release Candidate 1: We are pleased to announce the first Release Candidate for IronPython 2.7. This release contains over two dozen bugs fixed in preparation for 2.7 Final. See the release notes for 60193 for details and what has already been fixed in the earlier 2.7 prereleases. - IronPython TeamCaliburn Micro: A Micro-Framework for WPF, Silverlight and WP7: Caliburn.Micro 1.0 RC: This is the official Release Candicate for Caliburn.Micro 1.0. The download contains the binaries, samples and VS templates. VS Templates The templates included are designed for situations where the Caliburn.Micro source needs to be embedded within a single project solution. This was targeted at government and other organizations that expressed specific requirements around using an open source project like this. NuGet This release does not have a corresponding NuGet package. The NuGet pack...Caliburn: A Client Framework for WPF and Silverlight: Caliburn 2.0 RC: This is the official Release Candidate for Caliburn 2.0. It contains all binaries, samples and generated code docs.Rawr: Rawr 4.0.20 Beta: Rawr is now web-based. The link to use Rawr4 is: http://elitistjerks.com/rawr.phpThis is the Cataclysm Beta Release. More details can be found at the following link http://rawr.codeplex.com/Thread/View.aspx?ThreadId=237262 As of the 4.0.16 release, you can now also begin using the new Downloadable WPF version of Rawr!This is a pre-alpha release of the WPF version, there are likely to be a lot of issues. If you have a problem, please follow the Posting Guidelines and put it into the Issue Trac...Windows Phone 7 Isolated Storage Explorer: WP7 Isolated Storage Explorer v1.0 Beta: Current release features:WPF desktop explorer client Visual Studio integrated tool window explorer client (Visual Studio 2010 Professional and above) Supported operations: Refresh (isolated storage information), Add Folder, Add Existing Item, Download File, Delete Folder, Delete File Explorer supports operations running on multiple remote applications at the same time Explorer detects application disconnect (1-2 second delay) Explorer confirms operation completed status Explorer d...New Projectsconvert digit to word upto thousand: convert digit to word upto thousandCustom XSLT with recursive loop in Biztalk 2009: Custom XSLT with recursive loop in Biztalk 2009ECO contrib: ECO ist a excellent framework for domain driven design developed by CapableObjects AB. Share your additional features in this contrib project.euler21: euler 21euler22: euler 22 problemflowless: Some workflow thingHFR7 - Forum Hardware.fr pour Windows Phone 7: HFR7 vous permet de surfer sur le forum de Hardware.fr via votre Windows Phone. Il est développé sous Silverlight (C#/XAML).ISP.NET: ISP.NET is a code level verification tool for MPI programs. It includes a Visual Studio 2010 extension that allows for push button verification of user programs that are written in C, C++ and C#. ISP checks for deadlocks, assertion violations, and other MPI program issues. IVY Frameworks: Ivy Frameworks is an architectural framework to create multi-tire application in a consistent way. We are creating specific application blocks. When completed it will help to create a software development pattern, to mass produce .Net applications in a software factory model. Jobeet: Just another Symfony Tutorial I'm following.Lurity: Project Codename "Lurity".Metro Toolkit: Metro ToolkitMySchoolManager: MySchoolManager es un programa de fines didácticos, de código fuente abierto y documentado en español, que simula un sistema de administración del personal de una escuela. NewRapp: Project at KTH in course DD2388NHibernateCMS: NHibernateCMSParametero - Yet Another Console Arguments Parsing Library: Parametero - Yet Another Console Arguments Parsing LibraryRasifiel's test: Test projectSilverlight Gantt Chart: Don't waste time creating your own Gantt Chart. We've already done it!SKWebSite: This is my first ASP.NET MVC3 projectTechChat: TechChat is a ASP.net AJAX based stylish chat room. It demonstrates the use of database and use of AJAX. It is developed in VB.netUDK Development Kit Addons: UDK Development Kit Addons makes it easier for UDK users to develop and debug UDK scripts. It's developed in C# with using Visual Studio Shell.UltraLight.mvvm Windows Phone 7 MVVM Framework: A lightweight (< 300 lines, < 25KB) framework for developing MVVM Silverlight applications with support for tombstoning on the Windows Phone 7.Website Panel: Website PanelxMS (eXtensible Management System): The xMS is a simple console that can be extended using plugins. Those plugins can be written by developers using a simple interface. It's a good starting for who want to develop a plugin based application.Xna Midi Project: A project that will allow midi functionality using only the compact framework for windows and Xbox solutions.

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• What follows after lexical analysis?

  - by madflame991

  I'm working on a toy compiler (for some simple language like PL/0) and I have my lexer up and running. At this point I should start working on building the parse tree, but before I start I was wondering: How much information can one gather from just the string of tokens? Here's what I gathered so far: One can already do syntax highlighting having only the list of tokens. Numbers and operators get coloured accordingly and keywords also. Autoformatting (indenting) should also be possible. How? Specify for each token type how many white spaces or new line characters should follow it. Also when you print tokens modify an alignment variable (when the code printer reads "{" increment the alignment variable by 1, and decrement by 1 for "}". Whenever it starts printing on a new line the code printer will align according to this alignment variable) In languages without nested subroutines one can get a complete list of subroutines and their signature. How? Just read what follows after the "procedure" or "function" keyword until you hit the first ")" (this should work fine in a Pascal language with no nested subroutines) In languages like Pascal you can even determine local variables and their types, as they are declared in a special place (ok, you can't handle initialization as well, but you can parse sequences like: "var a, b, c: integer") Detection of recursive functions may also be possible, or even a graph representation of which subroutine calls who. If one can identify the body of a function then one can also search if there are any mentions of other function's names. Gathering statistics about the code, like number of lines, instructions, subroutines EDIT: I clarified why I think some processes are possible. As I read comments and responses I realise that the answer depends very much on the language that I'm parsing.

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• Pattern for a class that does only one thing

  - by Heinzi

  Let's say I have a procedure that does stuff: void doStuff(initalParams) { ... } Now I discover that "doing stuff" is quite a compex operation. The procedure becomes large, I split it up into multiple smaller procedures and soon I realize that having some kind of state would be useful while doing stuff, so that I need to pass less parameters between the small procedures. So, I factor it out into its own class: class StuffDoer { private someInternalState; public Start(initalParams) { ... } // some private helper procedures here ... } And then I call it like this: new StuffDoer().Start(initialParams); or like this: new StuffDoer(initialParams).Start(); And this is what feels wrong. When using the .NET or Java API, I always never call new SomeApiClass().Start(...);, which makes me suspect that I'm doing it wrong. Sure, I could make StuffDoer's constructor private and add a static helper method: public static DoStuff(initalParams) { new StuffDoer().Start(initialParams); } But then I'd have a class whose external interface consists of only one static method, which also feels weird. Hence my question: Is there a well-established pattern for this type of classes that have only one entry point and have no "externally recognizable" state, i.e., instance state is only required during execution of that one entry point?

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• What .NET objects should I use to create a cookie based session in MVC?

  - by makerofthings7

  I'm writing a custom password reset application that uses a validation technique that doesn't fit cleanly with ASP.NET Membership Provider's challenge questions. Namely I need to invoke a workflow and collect information from the end user (backup phone number, email address) after the user logs in using a custom form. The only way I know to create a cookie-based session (without too much "innovation" on my part) is to use WIF. What other standard objects can I use with ASP.NET MVC to create an authenticated session that works with non-windows user stores? Ideally I can store "role" or claim information in the session object such as "admin", "departmentXadmin", "normalUser", or "restrictedUser" The workflow would look like this: User logs in with username and password If the username and pw are correct a (stateless) cookie based session is created The user gets redirected to a HTML form that allows them to enter their backup phone number (for SMS dual factor), or validate it if already set. The user can then change their password using the form provided The "forgot password" would look like this User requests OTP code to be sent to the phone User logs in using username and OTP If the OTP is valid and not expired then create a cookie based session and redirect to a form that allows password reset Show password reset form, and process results.

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• Algorithm to reduce calls to mapping API

  - by aidan

  A random distribution of points lies on a map. This data lies behind an API, and I want to grab the complete set of points within a given bounding box. I can query the API with the bounding box and the API will return the set of points that fall within that box. The problem is that the API will limit the result set to 10 items, with no pagination and no indication if there are more points that have been omitted. So I made a recursive algorithm that takes a bounding box and requests the points that lie within it. If the result set is exactly 10 items, then I split the bounding box into four quadrants and recurse. It works fine but my question is this: if want to minimize the number of API calls, what is the optimal way to split the bounding box? Splitting it into quadrants was just an arbitrary decision. When there are a lot of points on the map, I have to drill down many levels before I start getting meaningful results. So I imagine it might be faster to split the box into, say, 9, 16, or more sections. But if I do that, then I eventually get to a point where a lot of requests are returning 0 results which isn't so efficient. Also, does the size of the limit on the results set affect the answer? (This is all assuming that I have no prior knowledge of nominal point density in the bounding box)

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• Breaking The Promise of Web Service Interoperability

  The promise of web service interoperability is achievable if certain technical and non-technical issues are dealt with properly. As the world gets smaller and smaller thanks to our growing global economy the need for security is increasing. The use of security is vital in the transferring of data from one server to another. As new security standards and protocols are created, the environments for web service hosts and clients must be in sync so that they can communicate on the same standard and protocols. For example, if a new protocol x can only be implemented on computers built after 2010 then all computers built prior to 2010 will not be able to connect to any web service hosts that only use this protocol in its security policy. If both the host and client of a web service cannot communicate using a set of common standards and protocols then web services are not available to these clients thus breaking the promise of interoperability. Another limiting factor of web services is governmental policies and regulations. I have experienced this first hand last year when I had to work on a project that dealt with personally identifiable information (PII) regarding US and Canadian Citizens. Currently the Canadian government regulates that any data pertaining to Canadian citizens must be store in Canada only. The issue that we had was that fact that we are a US based company that sometimes works with Canadian PII as part of a service that we provide. As you can see we are US based company and dealing with Canadian Data, so we had to place a file server inside the border of Canada in order for us to continue working for our Canadian customers.

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• vector rotations for branches of a 3d tree

  - by freefallr

  I'm attempting to create a 3d tree procedurally. I'm hoping that someone can check my vector rotation maths, as I'm a bit confused. I'm using an l-system (a recursive algorithm for generating branches). The trunk of the tree is the root node. It's orientation is aligned to the y axis. In the next iteration of the tree (e.g. the first branches), I might create a branch that is oriented say by +10 degrees in the X axis and a similar amount in the Z axis, relative to the trunk. I know that I should keep a rotation matrix at each branch, so that it can be applied to child branches, along with any modifications to the child branch. My questions then: for the trunk, the rotation matrix - is that just the identity matrix * initial orientation vector ? for the first branch (and subsequent branches) - I'll "inherit" the rotation matrix of the parent branch, and apply x and z rotations to that also. e.g. using glm::normalize; using glm::rotateX; using glm::vec4; using glm::mat4; using glm::rotate; vec4 vYAxis = vec4(0.0f, 1.0f, 0.0f, 0.0f); vec4 vInitial = normalize( rotateX( vYAxis, 10.0f ) ); mat4 mRotation = mat4(1.0); // trunk rotation matrix = identity * initial orientation vector mRotation *= vInitial; // first branch = parent rotation matrix * this branches rotations mRotation *= rotate( 10.0f, 1.0f, 0.0f, 0.0f ); // x rotation mRotation *= rotate( 10.0f, 0.0f, 0.0f, 1.0f ); // z rotation Are my maths and approach correct, or am I completely wrong? Finally, I'm using the glm library with OpenGL / C++ for this. Is the order of x rotation and z rotation important?

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• (PHP vs Python vs Perl) vs Ruby [closed]

  - by Dr.Kameleon

  OK, here's what : I've programmed in over 20 different languages and now, because of a large project I'm currently working on for Mac OS X (in Objective-C/Cocoa), I need to make a final decision on which language to use for my background scripting + plugin functionality. Definitely, one factor that'll ultimately influence my decision is which one I'm most familiar with, which is PHP (one of the ugliest languages around, which I however adore... lol), then Python / Perl (the "proven values"... )... and then Ruby (which, to me, is almost confusing and I've only played with it for some time.) Now, here's my considerations : (As previously mentioned) Being familiar with it (anyway, if X is better in my case, I really don't mind studying it from scratch...) Speed Good interaction with the Shell + ease of integration with my Cocoa application Btw, some of the reasons that made me wonder if Ruby would be a good choice is : The hype around it (although, I still don't get why; but that's probably just me...) My major competitor (we're actually talking about the same type of software here) is using Ruby for its backend scripting almost exclusively (ok, along with some BASH). Isn't Ruby considered slower e.g. than Perl? Why did he choose that? Simply, a matter of personal taste? So... your thoughts?

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• Precision loss when transforming from cartesian to isometric

  - by Justin Skiles

  My goal is to display a tile map in isometric projection. This tile map has 25 tiles across and 25 tiles down. Each tile is 32x32. See below for how I'm accomplishing this. World Space World Space to Screen Space Rotation (45 degrees) Using a 2D rotation matrix, I use the following: double rotation = Math.PI / 4; double rotatedX = ((tileWorldX * Math.Cos(rotation)) - ((tileWorldY * Math.Sin(rotation))); double rotatedY = ((tileWorldX * Math.Sin(rotation)) + (tileWorldY * Math.Cos(rotation))); World Space to Screen Space Scale (Y-axis reduced by 50%) Here I simply scale down the Y value by a factor of 0.5. Problem And it works, kind of. There are some tiny 1px-2px gaps between some of the tiles when rendering. I think there's some precision loss somewhere, or I'm not understanding how to get these tiles to fit together perfectly. I'm not truncating or converting my values to non-decimal types until I absolutely have to (when I pass to the render method, which only takes integers). I'm not sure how to guarantee pixel perfect rendering precision when I'm rotating and scaling on a level of higher precision. Any advice? Do I need to supply for information?

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• Floating point undesireable in highly critical code?

  - by Kirt Undercoffer

  Question 11 in the Software Quality section of "IEEE Computer Society Real-World Software Engineering Problems", Naveda, Seidman, lists fp computation as undesirable because "the accuracy of the computations cannot be guaranteed". This is in the context of computing acceleration for an emergency braking system for a high speed train. This thinking seems to be invoking possible errors in small differences between measurements of a moving object but small differences at slow speeds aren't a problem (or shouldn't be), small differences between two measurements at high speed are irrelevant - can there be a problem with small roundoff errors during deceleration for an emergency braking system? This problem has been observed with airplane braking systems resulting in hydroplaning but could this actually happen in the context of a high speed train? The concern about fp errors seems to not be well-founded in this context. Any insight? The fp is used for acceleration so perhaps the concern is inching over a speed limit? But fp should be just fine if they use a double in whatever implementation language. The actual problem in the text states: During the inspection of the code for the emergency braking system of a new high speed train (a highly critical, real-time application), the review team identifies several characteristics of the code. Which of these characteristics are generally viewed as undesirable? The code contains three recursive functions (well that one is obvious). The computation of acceleration uses floating point arithmetic. All other computations use integer arithmetic. The code contains one linked list that uses dynamic memory allocation (second obvious problem). All inputs are checked to determine that they are within expected bounds before they are used.

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• Elliptical orbit modeling

  - by Nathon

  I'm playing with orbits in a simple 2-d game where a ship flies around in space and is attracted to massive things. The ship's velocity is stored in a vector and acceleration is applied to it every frame as appropriate given Newton's law of universal gravitation. The point masses don't move (there's only 1 right now) so I would expect an elliptical orbit. Instead, I see this: I've tried with nearly circular orbits, and I've tried making the masses vastly different (a factor of a million) but I always get this rotated orbit. Here's some (D) code, for context: void accelerate(Vector delta) { velocity = velocity + delta; // Velocity is a member of the ship class. } // This function is called every frame with the fixed mass. It's a // method of the ship's. void fall(Well well) { // f=(m1 * m2)/(r**2) // a=f/m // Ship mass is 1, so a = f. float mass = 1; Vector delta = well.position - loc; float rSquared = delta.magSquared; float force = well.mass/rSquared; accelerate(delta * force * mass); }

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• What can be done against language inertia?

  - by gerrit

  Often, projects use programming language X, but would use programming language Y if they were started from scratch. For example, big numerical models may be written entirely in Fortran. Whereas this might be a reasonable choice for the components that need to run fast (alternative would be C or C++), it might be a poor choice for components that either do not need to run fast (such as things dealing with human input or simple visualisations), or where runtime is not the limiting factor (such as I/O, particularly when from the network). Another example may be when a project is built using a propriety language (such as Matlab; no, FOSS clones are not good enough) and was started at a time when FOSS alternatives were not viable, but ten years later, they are; and it would be beneficial to migrate. However, due to language inertia, a migration does not happen. Code that works should not be touched, porting code is a time-consuming, expensive process, and programmers are familiar in language X but not necessarily in language Y. Still, in the long term, a migration would likely be beneficial. Can anything be done to mitigate the problems associated with language inertia? Are there any notable examples of big projects that have successfully overcome this problem? Or is a project bound to stick forever with the initial choices?

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• How do references work in R?

  - by djechlin

  I'm finding R confusing because it has such a different notion of reference than I am used to in languages like C, Java, Javascript... Ruby, Python, C++, well, pretty much any language I have ever programmed in ever. So one thing I've noticed is variable names are not irrelevant when passing them to something else. The reference can be part of the data. e.g. per this tutorial a <- factor(c("A","A","B","A","B","B","C","A","C")) results <- table(a) Leads to $a showing up as an attribute as $dimnames$a. We've also witnessed that calling a function like a <- foo(alpha=1, beta=2) can create attributes in a of names alpha and beta, or it can assign or otherwise compute on 1 and 2 to properties already existing. (Not that there's a computer science distinction here - it just doesn't really happen in something like Javascript, unless you want to emulate it by passing in the object and use key=value there.) Functions like names(...) return lvalues that will affect the input of them. And the one that most got me is this. x <- c(3, 5, 1, 10, 12, 6) y = x[x <= 5] x[y] <- 0 is different from x <- c(3, 5, 1, 10, 12, 6) x[x <= 5] <- 0 Color me confused. Is there a consistent theory for what's going on here?

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• How does one find out which application is associated with an indicator icon in Ubuntu 12.04?

  - by Amos Annoy

  It is trivial to do this in Ubuntu 10.04. The question is specific to Ubuntu 12.04. This has nothing to do (does it?) with right click. How can an indicator's icon in Ubuntu 12.04 be matched with the program responsible for it's manifestation on the top panel? A list of running applications can include all processes using System Monitor. How is the correct matching process found for an indicator? (the examination of SM points out a rather poignant factor in the faster depletion and shortened run time on battery - the ambient quiescent CPU rate in 12.04 is now well over 20% when previously it was well under 10% in 10.04, between 5% and 7%!) (I have a problem with the battery indicator - it sometimes has % and other times hh:mm - it is necessary to know the ap. & v. to get more info on controlling same. ditto: There are issues with other indicator aps.) Details from: How can I find Application Indicator ID's? suggests looking at: file:///usr/share/indicator-application/ordering-override.keyfile [Ordering Index Overrides] nm-applet=1 gnome-power-manager=2 ibus=3 gst-keyboard-xkb=4 gsd-keyboard-xkb=5 which solves the battery identification, and presumably nm is NetworkManager for the rf icon, but the envelope, blue tooth and speaker indicator aps. are still a mystery. (Also, the ordering is not correlated.) Mind you, it was simple in the past to simply right click to get the About option to find the ap. & v. info. browsing around and about: file:///usr/share/indicator-application/ordering-override.keyfile examined: file:///usr/share/indicators file:///usr/share/indicators/messages/applications/ ... perhaps?/presumably? the information sought may be buried in file:///usr/share/indicators

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• Suggestions required to build an ECommerce Platform

  - by Haris

  For a prospective client we have to offer a solution to provide following system: CMS Order Management Shopping Cart CRM Helpdesk Accounting & Finance Custom Functions In order to save time and to avoid reinvent the wheel our idea is to integrate different off-the-shelf solutions. Their first requirement is that the system has to be hosted in their country which I think will exclude application like Aplicor, Netsuite & Salesforce. Basically the nucleaus would be the CMS which would integrate all the other apps. PHP or .Net based solutions would be our preferences as have inhouse expertise. So far following are few combinations I have come up with: Joomla (CMS) + Virtuemart (Cart+Ordering) + Sugar CRM + Open ERP (finance) + OTRS Magento (CMS+Cart+Ordering) + Sugar CRM + Open ERP (finance) + Helpdesk Ultimate Drupal (CMS) + Ubercart (Cart+Ordering) + Sugar CRM + Open ERP (finance) + Support Ticketing System Sharepoint (CMS) + OptimusBt (Cart+Ordering) + Dynamics CRM + Great Plains + SharepointHQ Dotnetnuke (CMS) + DNNSpot (Cart+Ordering) + Sigma Pro (CRM+Helpdesk) + Open ERP For Helpdesk I liked Zendesk but the server location was the stopping factor, similar for finance and CRM I liked Aplicor. I would not like to go into detailed requirements as it would make things very complex. Could you please suggest me which options are worth enough to start looking into? What other options we have?

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• Easily Add Program Shortcuts to the Desktop Context Menu in Windows 7

  - by Lori Kaufman

  If you use the Desktop context menu often, wouldn’t it be useful if you could add program shortcuts to it so you can quickly access your favorite apps? We’ve shown you how to do this using a quick registry tweak, but there’s an easier way. DeskIntegrator is a free, portable program that allows you to quickly and easily add applications to the Desktop context menu. It does not need to be installed. Extract the program files from the .zip file you downloaded (see the link at the end of the article) to a location on your hard drive. NOTE: This article shows you how to use DeskIntegrator in Windows 7, but we tested it in Windows 8 Release Preview and it worked there as well. To use DeskIntegrator, you must run it as administrator. Right-click on the DeskIntegrator.exe file and select Run as administrator from the popup menu. HTG Explains: What Is Two-Factor Authentication and Should I Be Using It? HTG Explains: What Is Windows RT and What Does It Mean To Me? HTG Explains: How Windows 8′s Secure Boot Feature Works & What It Means for Linux

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• HTG Explains: The Best and Worst Ways to Send a Resume

  - by Eric Z Goodnight

  With so many people looking for jobs, the slightest edge in your resume presentation has potential to make or break your chances. But not all filetypes or methods are created equal—read on to see the potential pitfalls your resume faces. In this article, we’ll explore what can go wrong in a resume submission, what can be done to counteract it, and also go into why a prospective employer might ignore your resume based on your method of sending a resume. Finally, we’ll cover the best filetypes and methods that can help get you that new job you’ve been looking for. What Sets Your Resume Apart? Latest Features How-To Geek ETC Internet Explorer 9 RC Now Available: Here’s the Most Interesting New Stuff Here’s a Super Simple Trick to Defeating Fake Anti-Virus Malware How to Change the Default Application for Android Tasks Stop Believing TV’s Lies: The Real Truth About "Enhancing" Images The How-To Geek Valentine’s Day Gift Guide Inspire Geek Love with These Hilarious Geek Valentines The Citroen GT – An Awesome Video Game Car Brought to Life [Video] Four Awesome TRON Legacy Themes for Chrome and Iron Anger is Illogical – Old School Style Instructional Video [Star Trek Mashup] Get the Old Microsoft Paint UI Back in Windows 7 Relax and Sleep Is a Soothing Sleep Timer Google Rolls Out Two-Factor Authentication

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• Why is Desktop Unity using the global application menu?

  - by Kazade

  It was announced in another question that the desktop version of Unity will keep the global menu by default. Here are the facts: The global menu was introduced into UNE to save vertical screen space because at Netbook resolutions the vertical space is limited. On a modern desktop with a high resolution, there is ample vertical space making this unnecessary On the announcement of UNE global menus, Mark Shuttleworth himself said the following: "There are outstanding questions about the usability of a panel-hosted menu on much larger screens, where the window and the menu could be very far apart." The benefits of a global menu don't seem to carry across to a high-resolution desktop and instead seem to bring draw backs (increased mouse travel, large distance between the menu and its associated window). The other worrying factor is that applications seem to be moving away from having a menu bar, and instead of innovating on this and defining new guidelines for moving away from the menu, we are giving it prime place right at the top of the desktop. If applications continue moving away from the desktop we will have an inconsistent experience concerning where to locate application related options/tools depending on which app you are using (e.g. Chrome). Finally, the current global menu bar implementation doesn't work for all apps, and doesn't even work for all apps in the default install. This means that the default desktop implementation will be inconsistent. So, there are a bunch of reasons why moving to a global menu is a bad idea, so we need some pretty convincing arguments for why it is a good idea. What are the reasons for the global menu implementation in the desktop version of Unity?

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• Algorithmic problem - quickly finding all #'s where value %x is some given value

  - by Steve B.

  Problem I'm trying to solve, apologies in advance for the length: Given a large number of stored records, each with a unique (String) field S. I'd like to be able to find through an indexed query all records where Hash(S) % N == K for any arbitrary N, K (e.g. given a million strings, find all strings where HashCode(s) % 17 = 5. Is there some way of memoizing this so that we can quickly answer any question of this form without doing the % on every value? The motivation for this is a system of N distributed nodes, where each record has to be assigned to at least one node. The nodes are numbered 0 - (K-1) , and each node has to load up all of the records that match it's number: If we have 3 nodes Node 0 loads all records where Hash % 3 ==0 Node 1 loads all records where Hash % 3 ==1 Node 2 loads all records where Hash % 3 ==2 adding a 4th node, obviously all the assignments have to be recomputed - Node 0 loads all records where Hash % 4 ==0 ... etc I'd like to easily find these records through an indexed query without having to compute the mod individually. The best I've been able to come up with so far: If we take the prime factors of N (p1 * p2 * ... ) if N % M == I then p % M == I % p for all of N's prime factors e.g. 10 nodes : N % 10 == 6 then N % 2 = 0 == 6 %2 N % 5 = 1 == 6 %5 so storing an array of the "%" of N for the first "reasonable" number of primes for my data set should be helpful. For example in the above example we store the hash and the primes HASH PRIMES (array of %2, %3, %5, %7, ... ]) 16 [0 1 1 2 .. ] so looking for N%10 == 6 is equivalent to looking for all values where array[1]==1 and array[2] == 1. However, this breaks at the first prime larger than the highest number I'm storing in the factor table. Is there a better way?

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• Coordinate spaces and transformation matrices

  - by Belgin

  I'm trying to get an object from object space, into projected space using these intermediate matrices: The first matrix (I) is the one that transforms from object space into inertial space, but since my object is not rotated or translated in any way inside the object space, this matrix is the 4x4 identity matrix. The second matrix (W) is the one that transforms from inertial space into world space, which is just a scale transform matrix of factor a = 14.1 on all coordinates, since the inertial space origin coincides with the world space origin. /a 0 0 0\ W = |0 a 0 0| |0 0 a 0| \0 0 0 1/ The third matrix (C) is the one that transforms from world space, into camera space. This matrix is a translation matrix with a translation of (0, 0, 10), because I want the camera to be located behind the object, so the object must be positioned 10 units into the z axis. /1 0 0 0\ C = |0 1 0 0| |0 0 1 10| \0 0 0 1/ And finally, the fourth matrix is the projection matrix (P). Bearing in mind that the eye is at the origin of the world space and the projection plane is defined by z = 1, the projection matrix is: /1 0 0 0\ P = |0 1 0 0| |0 0 1 0| \0 0 1/d 0/ where d is the distance from the eye to the projection plane, so d = 1. I'm multiplying them like this: (((P x C) x W) x I) x V, where V is the vertex' coordinates in column vector form: /x\ V = |y| |z| \1/ After I get the result, I divide x and y coordinates by w to get the actual screen coordinates. Apparenly, I'm doing something wrong or missing something completely here, because it's not rendering properly. Here's a picture of what is supposed to be the bottom side of the Stanford Dragon: Also, I should add that this is a software renderer so no DirectX or OpenGL stuff here.

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• Why isn't my other two constant buffers being updated to the shader?

  - by Paul Ske

  I posted previously before about my two dynamic buffers not being dynamically updating the constant shader. The tessellation buffer isn't working because I have to manually update the tessellation factor inside the hull shader. I believe the camera position isn't updating either because when I perform distance adaptation the far edges are more tessellated then the what's truly in front of the camera. I have all the buffers set to dynamic. Inside the render loop I have them set as: ID3D11Buffer *multiBuffers[3]; devcon->VSSetConstantBuffers(0,3,multiBuffers); ... devcon->DSSetConstantBuffers(0,3,multiBuffers); I only got that from a directX Sample. Inside the shader file I have the three cbuffer structs. cbuffer ConstantBuffer { float4x4 WorldMatrix; float4x4 viewMatrix; float4x4 projectionMatrix; float4x4 modelWorldMatrix; // the rotation matrix float3 lightvec; // the light's vector float4 lightcol; // the light's color float4 ambientcol; // the ambient light's color bool isSelected; } cbuffer cameraBuffer { float3 cameraDirection; float padding; } cbuffer TessellationBuffer { float tessellationAmount; float3 padding2; } Am I missing something or would anyone know why wouldn't my buffers update to the shader file?

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• Failed Project: When to call it?

  - by Dan Ray

  A few months ago my company found itself with its hands around a white-hot emergency of a project, and my entire team of six pulled basically a five week "crunch week". In the 48 hours before go-live, I worked 41 of them, two back to back all-nighters. Deep in the middle of that, I posted what has been my most successful question to date. During all that time there was never any talk of "failure". It was always "get it done, regardless of the pain." Now that the thing is over and we as an organization have had some time to sit back and take stock of what we learned, one question has occurred to me. I can't say I've ever taken part in a project that I'd say had "failed". Plenty that were late or over budget, some disastrously so, but I've always ended up delivering SOMETHING. Yet I hear about "failed IT projects" all the time. I'm wondering about people's experience with that. What were the parameters that defined "failure"? What was the context? In our case, we are a software shop with external clients. Does a project that's internal to a large corporation have more space to "fail"? When do you make that call? What happens when you do? I'm not at all convinced that doing what we did is a smart business move. It wasn't my call (I'm just a code monkey) but I'm wondering if it might have been better to cut our losses, say we're not delivering, and move on. I don't just say that due to the sting of the long hours--the company royally lost its shirt on the project, plus the intangible costs to the company in terms of employee morale and loyalty were large. Factor that against the PR hit of failing to deliver a high profile project like this one was... and I don't know what the right answer is.

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