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• Why might different computers calculate different arithmetic results in VB.NET?

  - by Eyal

  I have some software written in VB.NET that performs a lot of calculations, mostly extracting jpegs to bitmaps and computing calculations on the pixels like convolutions and matrix multiplication. Different computers are giving me different results despite having identical inputs. What might be the reason? Edit: I can't provide the algorithm because it's proprietary but I can provide all the relevant operations: ULong \ ULong (Turuncating division) Bitmap.Load("filename.bmp') (Load a bitmap into memory) Bitmap.GetPixel(Integer, Integer) (Get a pixel's brightness) Double + Double Double * Double Math.Sqrt(Double) Math.PI Math.Cos(Double) ULong - ULong ULong * ULong ULong << ULong List.OrderBy(Of Double)(Func) Hmm... Is it possible that OrderBy is using a non-stable QuickSort and that QuickSort is using a random pivot? Edit: Just tested, nope. The sort is stable.

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• Typecasting a floating value or using the math.h floor* functions?

  - by nobody

  Hi, I am coding up an implementation of Interpolation Search in C. The question is actually rather simple, I need to use the floating operations to do linear interpolation to find the correct index which will eventually be an integer result. In particular my probe index is: t = i + floor((((k-low)/(high-low)) * (j-i))); where, i,j,k,t are unsigned ints, and high,low are doubles. Would this be equivalent to: t = i + (unsigned int)(((k-low)/(high-low)) * (j-i)); Is there any reason I would actually want to use math.h floor* functions over just a simple (int) typecast?

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• How to replace values in multi-valued ESE column?

  - by Soonts

  I have a multi-valued short ASCII text column in one of the tables in my ESE database, that holds the person's phone numbers. I have the new set of values, and I'd like to wipe the old values completely, and only use the new values. The JET_bitSetRevertToDefaultValue bit doesn't seem to work. While the MSDN documentation says "It causes the column to return the default column value on subsequent retrieve column operations. All existing column values are removed.", I found that it does nothing (no return value is returned). Or, is there an easy way to find out how many values does the column contain (this could be zero, e.g. when I'm doing an insertion, not update)? If it was, I could just run a loop from 'nValues' to 1, erasing the value by setting it to the null while providing the itagSequence value, to achieve what I want. I'm programming C#, and using the latest version of ManagedEsent library. Thanks in advance!

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• Making sure unsigned int/long always execute in checked context in C#

  - by theburningmonk

  Has anyone found it strange that the default context for uint and ulong is unchecked rather than checked considering that they are meant to represent values that can never be negative? So if some code is trying to violate that constraint it seems to me the natural and preferred behaviour would be to throw an exception rather than returning the max value instead (which can easily leave important pieces of data in an invalid state and impossible to revert..). Is there an existing attribute which can be applied to either class/assembly so that it always performs arithmetic operations in a checked context? I was thinking of writing one myself (as an aspect using PostSharp) but would be great if there's one already. Many thanks,

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• SmartGWT Server File Browser

  - by jluzwick

  Hi All: I have been looking for a SmartGWT example that would show me how to build a File Browser widget that takes the files from the local server's root directory. The user would be shown the files through the browser which they could then select to perform some processing operations. So far I have thought of using SmartGWT's Tree-Data Binding-Load from Local Data Widget and then grabbing a list of the directories using: new File("\").listFiles(); My Question is: Is there a better way to do this? Has someone already thought of this and has an example of their code that I can see? PS: I'm fairly new to GWT and Web Services but fairly competent with Java. If you believe there is a better way to do this (while still doing this through the web and not using Applets, please tell me). Thanks

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• Strategies for generating Zend Cache Keys

  - by emeraldjava

  ATM i'm manually generating a cache key based on the method name and parameters, then follow to the normal cache pattern. This is all done in the Controller and i'm calling a model class that 'extends Zend_Db_Table_Abstract'. public function indexAction() { $cache = Zend_Registry::get('cache'); $individualleaguekey = sprintf("getIndividualLeague_%d_%s",$leagueid,$division->code); if(!$leaguetable = $cache->load($individualleaguekey)) { $table = new Model_DbTable_Raceresult(); $leaguetable = $table->getIndividualLeague($leagueid,$division,$races); $cache->save($leaguetable, $individualleaguekey); } $this->view->leaguetable = $leaguetable; .... I want to avoid the duplication of parameters to the cache creation method and also to the model method, so i'm thinking of moving the caching logic away from my controller class and into model class packaged in './model/DbTable', but this seems incorrect since the DB model should only handle SQL operations. Any suggestions on how i can implement a clean patterned solution?

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• Interpreters: How much simplification?

  - by Ray

  In my interpreter, code like the following x=(y+4)*z echo x parses and "optimizes" down to four single operations performed by the interpreter, pretty much assembly-like: add 4 to y multiply <last operation result> with z set x to <last operation result> echo x In modern interpreters (for example: CPython, Ruby, PHP), how simplified are the "opcodes" for which are in end-effect run by the interpreter? Could I achieve better performance when trying to keep the structures and commands for the interpreter more complex and high-level? That would be surely a lot harder, or?

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• Have the default security settings changed in Windows 7 that would affect IPrincipal.IsInRole?

  - by adrianbanks

  We use NTLM auth in our application to determine whether a user can perform certain operations. We use the IPrincipal of their current Windows login (in WinForms applications), calling IsInRole to check for specific group memberships. To check that a user is a local administrator on the machine, we use: AppDomain.CurrentDomain.SetPrincipalPolicy(PrincipalPolicy.WindowsPrincipal); ... bool allowed = Thread.CurrentPrincipal.IsInRole(@"Builtin\Administrators") This works if the current user is the Administrator user, or is another user that is a member of the Builtin\Administrators group. In our testing on Windows 7, we have found that this no longer works as expected. The Administrator user still works fine, but any other user that is a member of the Builtin\Administrators group returns false for the IsInRole call. What could be causing this difference? I have a gut feeling that a default setting has changed somewhere (possible in gpedit), but cannot find anything that looks like the culprit.

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• Prolog - Finding the current directory, relative directory for 'tell' predicate

  - by Bharat

  I'm having trouble trying to figure out how to get prolog to spit out a text file where I want it to. I'm currently doing a bunch of operations and then using tell('output.txt') to record the output. Now the problem is that when I do this, it creates this file in the SWI \bin\ folder. I was wondering if there's a way to make it create this file in the directory containing the actual .pl file. So even if the file was moved (and it will be), the text file gets created right where the source file is. Long story short, is there a way to get the location of the source file once the source file has been consulted? Many Thanks!

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• Why does order matter for ImageMagick's -colorspace operation?

  - by Mark Trapp

  Starting with ImageMagick 6, the command style changed to solve a bunch of problems outlined in the Basic Usage document. That document does imply that for simple operations, one should only need to move the options from before the source file to between the source and output files to convert from the "old" style to the "new" style. However, this doesn't seem to work for the -colorspace operation. When I use the following command, I get an output file with the correct colors: convert -colorspace rgb input.pdf output.png But when I try to use the new command style, the -colorspace operation is never applied: convert input.pdf -colorspace rgb output.png Samples: Why does this occur?

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• Int PK inner join Vs Guid PK inner Join on SQL Server. Execution plan.

  - by bigb

  I just did some testing for Int PK join Vs Guid PK. Tables structure and number of records looking like that: Performance of CRUD operations using EF4 are pretty similar in both cases. As we know Int PK has better performance rather than strings. So SQL server execution plan with INNER JOINS are pretty different Here is an execution plan. As i understand according with execution plan from attached image Int join has better performance because it is taking less resources for Clustered index scan and it is go in two ways, am i right? May be some one may explain this execution plan in more details?

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• App engine downtime

  - by DutrowLLC

  I've noticed that google app engine seems to have a fair amount of downtime where they place the datastore into read-only mode. Frequently this downtime is in the middle of the day. Is this something that is happening only during early development, or is this something that I can expect to be always be occurring? I've developing an application that helps small businesses handle their operations. One thing that it does is take appointments, another is route phone calls. I'd like some suggestions on how to handle times when the datastore is in read-only such as: What if our client is on the phone with the customer and is taking down an appointment and the datastore is in read-only? It would not be acceptable to ask the client to come back later to save, especially if its in the middle of the day. What if there is an incoming call and the application can not store the record or properly route the call due to database writes being unavailable? How are these types of issues normally handled?

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• Comparison of collection datatypes in C#

  - by Joel in Gö

  Does anyone know of a good overview of the different C# collection types? I am looking for something showing which basic operations such as Add, Remove, RemoveLast etc. are supported, and giving the relative performance. It would be particularly interesting for the various generic classes - and even better if it showed eg. if there is a difference in performance between a List<T> where T is a class and one where T is a struct. A start would be a nice cheat-sheet for the abstract data structures, comparing Linked Lists, Hash Tables etc. etc. Thanks!

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• Best Ruby ORM for Wrapping around Legacy SQL Server Database?

  - by Technocrat

  Hi. I found this answer and it sounds like almost exactly what I'm doing. I have heard mixed answers about whether or not datamapper can support SQL Server through dataobjects. Basically, we have an app that uses a consistently structured database, consistently named tables, etc in SQL Server. We're making all kinds of tools and stuff that have to interact with it, some of them remotely and so I decided that we need to create some common, simple access point to do read/write operations on the SQL Server app since it's API is all C# and other things I despise. Now my question is if anyone has any examples or projects they know of where a ruby ORM can essentially create models for another application's legacy database by defining the conventions of each model's pkeys, fkeys, table names, etc. Sequel is the only ORM I've used with SQL Server but never to do anything quite like this. Any suggestions?

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• When to use Vanilla Javascript vs. jQuery?

  - by jondavidjohn

  I have noticed while monitoring/attempting to answer common jQuery questions, that there are certain practices using javascript, instead of jQuery, that actually enable you to write less and do ... well the same amount. And may also yield performance benefits. A specific example $(this) vs this Inside a click event referencing the clicked objects id jQuery $(this).attr("id"); Javascript this.id; Are there any other common practices like this? Where certain Javascript operations could be accomplished easier, without bringing jQuery into the mix. Or is this a rare case? (of a jQuery "shortcut" actually requiring more code) EDIT : While I appreciate the answers regarding jQuery vs. plain javascript performance, I am actually looking for much more quantitative answers. While using jQuery, instances where one would actually be better off (readability/compactness) to use plain javascript instead of using $(). In addition to the example I gave in my original question.

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• Domain Model and Contracts

  - by devoured elysium

  I am modelling a DVD Rental Store: A Client gives its clientNumber to the System. The System checks whenever the given clientNumber is valid. The Client gives the name of the DVD he wants to rent. ... n. ...I will later have to form an association between a new instance of "RentDVD" class concept to the current Client c. My Domain Model is something like: I've made the Contract for the first and second operations as: Preconditions: none Postconditions: there exists a Client c such that c.clientNumber = clientNumber. Now, I don't know if I should form an association between this Client c and the DVDStore(that I intend to use as front-end). If I don't make the association, how will I later be able to "reference" this same Client? Should I be making an association between Client and a different concept? Thanks

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• Tweak Data in Doctrine Migration (say, by running some arbitrary queries)

  - by timdev

  I've got a migration that creates a couple of columns that act as foreign keys. In particular, I'm adding a creator_id and owner_id column to a model. These foreign keys indicate who created, and who currently owns, a particular kind of domain object. Users are managed by sfDoctrineGuardPlugin. What I'd like to do, for the purpose of the migration, is look up the (active) user with the lowest id, and default creator_id/owner_id to that. I don't see any particularly obvious/proper way to run arbitrary operations on the database during a migration. Does anyone know how?

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• ASP.NET MVC Generic Controllers and Spring.NET

  - by Jason

  Hello, I am creating an application using ASP.NET MVC (2) and Spring.NET. Since most of my Controller implementations just implement the similar CRUD operations, I would like to just create a single Generic controller, as explained here: http://stackoverflow.com/questions/848904/in-asp-net-mvc-is-it-possible-to-make-a-generic-controller However, the above example doesn't take DI frameworks into consideration. What I'm thinking is to create this (warning: this is an ugly mass of code I need help with): public SpringGenericControllerFactory : DefaultControllerFactory { public IController CreateController(RequestContext requestContext, string controllerName) { // Determine the controller type to return Type controllerType = Type.GetType("MyController").MakeGenericType(Type.GetType(controllerName)); // Return the controller return Activator.CreateInstance(controllerType) as IController; } } The entries in objects.xml would look something like this: <object id="controllerFactory" type="Application.Controllers.SpringGenericControllerFactory" /> <object id="DepartmentController" factory-method="CreateController" factory-object="controllerFactory" /> Can anyone pick through this and offer advice?

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• c++11 atomic ordering: extended total order memory_order_seq_cst for locks

  - by itaj

  There's this note in c++11 29.3-p3: [ Note: Although it is not explicitly required that S include locks, it can always be extended to an order that does include lock and unlock operations, since the ordering between those is already included in the "happens before" ordering. - end note ] What does it mean by "always"? I can understand that any certain implementation can be designed to support such an extended S. But in some general implementation that wasn't designed for it, I don't see that S can be extended so. I had sent this question to comp.std.c++ but got no answers there. http://groups.google.com/group/comp.std.c++/browse_frm/thread/5242fa70d0594d1b#

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• How to create project specific respository post-commit actions

  - by Pacifika

  Presently, we've got several main projects each in their own repository. We will have to version-control up to a dozen additional projects. VisualSVN recommends to create 1 respository for our company and then vc all projects inside that. It's a good practice to create one repository for the entire company or department and store all your projects in this repository. Creating separate repository for each project is not a good idea because in that case you will not be able to perform Subversion operations like copy, diff and merge cross-project. VisualSvn.com Currently we're using post-commit hooks to update the testing server with the latest commit and do other project specific actions (such as emailing certain people for one project but not for others) depending on which project has been committed. As post-commit runs for the whole repository, is this still possible in such a situation? How would I go about decerning which project has changes? filter folder structure?

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• Handling Dialogs in WPF with MVVM

  - by Ray Booysen

  In the MVVM pattern for WPF, handling dialogs is one of the more complex operations. As your view model does not know anything about the view, dialog communication can be interesting. I can expose an ICommand that when the view invokes it, a dialog can appear. Does anyone know of a good way to handle results from dialogs? I am speaking about windows dialogs such as MessageBox. One of the ways we did this was have an event on the viewmodel that the view would subscribe to when a dialog was required. public event EventHandler<MyDeleteArgs> RequiresDeleteDialog; This is OK, but it means that the view requires code which is something I would like to stay away from.

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• How should I port this Prototype to JQuery?

  - by blu

  There is currently this Prototype code that does a PUT: new Ajax.Request(someUrl, { method: 'put', parameters: { 'foo': bar }, onSuccess: function(response) { } .bind(this) }); I found this post but the solution uses an extra parameter supported by RoR, however I am targeting an ASP.NET backend. I searched a bit and found that not all browsers support PUT operations so apparently this could fail in certain browsers? This is already in prod, so a direct port would be fine for now I suppose. As an aside, what is the deal with the bind(this) in the onSuccess function?

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• Loading a DB table into nested dictionaries in Python

  - by Hossein

  Hi, I have a table in MySql DB which I want to load it to a dictionary in python. the table columns is as follows: id,url,tag,tagCount tagCount is the number of times that a tag has been repeated for a certain url. So in that case I need a nested dictionary, in other words a dictionary of dictionary, to load this table. Because each url have several tags for which there are different tagCounts.the code that I used is this:( the whole table is about 22,000 records ) cursor.execute( ''' SELECT url,tag,tagCount FROM wtp ''') urlTagCount = cursor.fetchall() d = defaultdict(defaultdict) for url,tag,tagCount in urlTagCount: d[url][tag]=tagCount print d first of all I want to know if this is correct.. and if it is why it takes so much time? Is there any faster solutions? I am loading this table into memory to have fast access to get rid of the hassle of slow database operations, but with this slow speed it has become a bottleneck itself, it is even much slower than DB access. and anyone help? thanks

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• Looking for solution to persist rows sequence in a database table that allow efficient reordering at

  - by Chau Chee Yang

  I have a database table. There is a field name "Sequence" that indicate sequence when user presents the rows in report or grid visually. When the rows are retrieved and presented in a grid, there are few UI gadget that allow user to reorder the rows arbitrary. The new sequence will be persist in database table when user commit the changes. Here are some UI operations: Move to first Move to last Move up 1 row Move down 1 row multi-select rows and move up or down multi-select rows and drag to new position For operation like "Move to first" or "Move to Last", it usually involve many rows and the sequence those rows would need to be updated accordingly. This may not be efficient enough at runtime. It is a common practice to use INTEGER as sequence's data type. Other solution is using "DOUBLE" or "FLOAT" that could overcome the mass update of row sequence but we will face problem if we reach the limit of precision.

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• C++ overloading virtual = operator

  - by taz

  Hello, here is the code for my question: class ICommon { public: virtual ICommon& operator=(const ICommon & p)const=0; }; class CSpecial : public ICommon { public: CSpecial& operator=(const CSpecial & cs) { //custom operations return *this; } }; CSpecial obj; Basically: I want the interface ICommon to force it's descendants to implement = operator but don't want to have any typecasts in the implementation. The compiler says "can't instantiate an abstract class. Any help/advice will be appreciated.

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