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  • Suppressing PostSharp Multicast with Attribute

    - by Dan Bryant
    I've recently started experimenting with PostSharp and I found a particularly helpful aspect to automate implementation of INotifyPropertyChanged. You can see the example here. The basic functionality is excellent (all properties will be notified), but there are cases where I might want to suppress notification. For instance, I might know that a particular property is set once in the constructor and will never change again. As such, there is no need to emit the code for NotifyPropertyChanged. The overhead is minimal when classes are not frequently instantiated and I can prevent the problem by switching from an automatically generated property to a field-backed property and writing to the field. However, as I'm learning this new tool, it would be helpful to know if there is a way to tag a property with an attribute to suppress the code generation. I'd like to be able to do something like this: [NotifyPropertyChanged] public class MyClass { public double SomeValue { get; set; } public double ModifiedValue { get; private set; } [SuppressNotify] public double OnlySetOnce { get; private set; } public MyClass() { OnlySetOnce = 1.0; } }

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  • Forward declaration of derived inner class

    - by Loom
    I ran into problem implementing some variations of factory method. // from IFoo.h struct IFoo { struct IBar { virtual ~IBar() = 0; virtual void someMethod() = 0; }; virtual IBar *createBar() = 0; }; // from Foo.h struct Foo : IFoo { // implementation of Foo, Bar in Foo.cpp struct Bar : IBar { virtual ~Bar(); virtual void someMethod(); }; virtual Bar *createBar(); // implemented in Foo.cpp }; I'd like to place declaration of Foo::Bar in Foo.cpp. For now I cannot succeed: struct Foo : IFoo { //struct Bar; //1. error: invalid covariant return type // for ‘virtual Foo::Bar* //struct Bar : IBar; //2. error: expected ‘{’ before ‘;’ token virtual Bar *createBar(); // virtual IBar *createBar(); // Is not acceptable by-design }; Is there a trick to have just forward declaration of Boo in Foo.hpp and to have full declaration in Foo.cpp?

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  • How to perform a binary search on IList<T>?

    - by Daniel Brückner
    Simple question - given an IList<T> how do you perform a binary search without writing the method yourself and without copying the data to a type with build-in binary search support. My current status is the following. List<T>.BinarySearch() is not a member of IList<T> There is no equivalent of the ArrayList.Adapter() method for List<T> IList<T> does not inherit from IList, hence using ArrayList.Adapter() is not possible I tend to believe that is not possible with build-in methods, but I cannot believe that such a basic method is missing from the BCL/FCL. If it is not possible, who can give the shortest, fastest, smartest, or most beatiful binary search implementation for IList<T>? UPDATE We all know that a list must be sorted before using binary search, hence you can assume that it is. But I assume (but did not verify) it is the same problem with sort - how do you sort IList<T>? CONCLUSION There seems to be no build-in binary search for IList<T>. One can use First() and OrderBy() LINQ methods to search and sort, but it will likly have a performance hit. Implementing it yourself (as an extension method) seems the best you can do.

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  • Is there a useDirtyFlag option for Tomcat 6 cluster configuration?

    - by kevinjansz
    In Tomcat 5.0.x you had the ability to set useDirtyFlag="false" to force replication of the session after every request rather than checking for set/removeAttribute calls. <Cluster className="org.apache.catalina.cluster.tcp.SimpleTcpCluster" managerClassName="org.apache.catalina.cluster.session.SimpleTcpReplicationManager" expireSessionsOnShutdown="false" **useDirtyFlag="false"** doClusterLog="true" clusterLogName="clusterLog"> ... The comments in the server.xml stated this may be used to make the following work: <% HashMap map = (HashMap)session.getAttribute("map"); map.put("key","value"); %> i.e. change the state of an object that has already been put in the session and you can be sure that this object still be replicated to the other nodes in the cluster. According to the Tomcat 6 documentation you only have two "Manager" options - DeltaManager & BackupManager ... neither of these seem to allow this option or anything like it. In my testing the default setup: <Cluster className="org.apache.catalina.ha.tcp.SimpleTcpCluster"/> where you get the DeltaManager by default, it's definitely behaving as useDirtyFlag="true" (as I'd expect). So my question is - is there an equivalent in Tomcat 6? Looking at the source I can see a manager implementation "org.apache.catalina.ha.session.SimpleTcpReplicationManager" which does have the useDirtyFlag but the javadoc comments in this state it's "Tomcat Session Replication for Tomcat 4.0" ... I don't know if this is ok to use - I'm guessing not as it's not mentioned in the main cluster configuration documentation.

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  • when an autoreleased object is actually released?

    - by psebos
    Hi, I am new in objective-c and I am trying to understand memory management to get it right. After reading the excellent Memory Management Programming Guide for Cocoa by apple my only concern is when actually an autoreleased object is released in an iphone/ipod application. My understanding is at the end of a run loop. But what defines a run loop in the application? So I was wondering whether the following piece of code is right. Assume an object @implementation Test - (NSString *) functionA { NSString *stringA; stringA = [[NSString alloc] initWithString:@"Hello" autorelease] return stringA; } - (NSString *) functionB { NSString *stringB; stringB = [self functionA]; return stringB; } - (NSString *) functionC { NSString *stringC; stringC = [self functionB]; return stringC; } - (void)viewDidLoad { [super viewDidLoad]; (NSString *) p = [self functionC]; NSLog(@"string is %@",p); } @end Is this code valid? From the apple text I understand that the NSString returned from functionA is valid in the scope of functionB. I am not sure whether it is valid in functionC and in viewDidLoad. Thanks!

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  • boost::shared_ptr in Objective-C++

    - by John Smith
    This is a better understanding of a question I had earlier. I have the following Objective-C++ object @interface OCPP { MyCppobj * cppobj; } @end @implementation OCPP -(OCPP *) init { cppobj = new MyCppobj; } @end Then I create a completely differently obj which needs to use cppobj in a boost::shared_ptr (I have no choice in this matter, it's part of a huge library which I cannot change) @interface NOBJ -(void) use_cppobj_as_shared_ptr { //get an OCPP obj called occ from somewhere.. //troubling line here } @end I have tried the following and that failed: I tried synthesising cppobj. Then I created a shared_ptr in "troubling line" in the following way: MyCppobj * cpp = [occ cppobj]; bsp = boost::shared_ptr<MyCppobj>(cpp); It works fine first time around. Then I destroy the NOBJ and recreate it. When I for cppobj it's gone. Presumably shared_ptr decided it's no longer needed and did away with it. So I need help. How can I keep cppobj alive? Is there a way to destroy bsp (or it's reference to cppobj) without destroying cppobj?

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  • Automatic testing of GUI related private methods

    - by Stein G. Strindhaug
    When it comes to GUI programming (at least for web) I feel that often the only thing that would be useful to unit test is some of the private methods*. While unit testing makes perfect sense for back-end code, I feel it doesn't quite fit the GUI classes. What is the best way to add automatic testing of these? * Why I think the only methods useful to test is private: Often when I write GUI classes they don't even have any public methods except for the constructor. The public methods if any is trivial, and the constructor does most of the job calling private methods. They receive some data from server does a lot of trivial output and feeds data to the constructor of other classes contained inside it, adding listeners that calls a (more or less directly) calls the server... Most of it pretty trivial (the hardest part is the layout: css, IE, etc.) but sometimes I create some private method that does some advanced tricks, which I definitely do not want to be publicly visible (because it's closely coupled to the implementation of the layout, and likely to change), but is sufficiently complicated to break. These are often only called by the constructor or repeatedly by events in the code, not by any public methods at all. I'd like to have a way to test this type of methods, without making it public or resorting to reflection trickery. (BTW: I'm currently using GWT, but I feel this applies to most languages/frameworks I've used when coding for GUI)

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  • ASP.NET SqlDataReader throwing error: Invalid attempt to call Read when reader is closed.

    - by Bugget
    This one has me stumped. Here are the relative bits of code: public AgencyDetails(Guid AgencyId) { try { evgStoredProcedure Procedure = new evgStoredProcedure(); Hashtable commandParameters = new Hashtable(); commandParameters.Add("@AgencyId", AgencyId); SqlDataReader AppReader = Procedure.ExecuteReaderProcedure("evg_getAgencyDetails", commandParameters); commandParameters.Clear(); //The following line is where the error is thrown. Errormessage: Invalid attempt to call Read when reader is closed. while (AppReader.Read()) { AgencyName = AppReader.GetOrdinal("AgencyName").ToString(); AgencyAddress = AppReader.GetOrdinal("AgencyAddress").ToString(); AgencyCity = AppReader.GetOrdinal("AgencyCity").ToString(); AgencyState = AppReader.GetOrdinal("AgencyState").ToString(); AgencyZip = AppReader.GetOrdinal("AgencyZip").ToString(); AgencyPhone = AppReader.GetOrdinal("AgencyPhone").ToString(); AgencyFax = AppReader.GetOrdinal("AgencyFax").ToString(); } AppReader.Close(); AppReader.Dispose(); } catch (Exception ex) { throw new Exception("AgencyDetails Constructor: " + ex.Message.ToString()); } } And the implementation of ExecuteReaderProcedure: public SqlDataReader ExecuteReaderProcedure(string ProcedureName, Hashtable Parameters) { SqlDataReader returnReader; using (SqlConnection conn = new SqlConnection(connectionString)) { try { SqlCommand cmd = new SqlCommand(ProcedureName, conn); SqlParameter param = new SqlParameter(); cmd.CommandType = System.Data.CommandType.StoredProcedure; foreach (DictionaryEntry keyValue in Parameters) { cmd.Parameters.AddWithValue(keyValue.Key.ToString(), keyValue.Value); } conn.Open(); returnReader = cmd.ExecuteReader(CommandBehavior.CloseConnection); } catch (SqlException e) { throw new Exception(e.Message.ToString()); } } return returnReader; } The connection string is working as other stored procedures in the same class run fine. The only problem seems to be when returning SqlDataReaders from this method! They throw the error message in the title. Any ideas are greatly appreciated! Thanks in advance!

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  • C Run-Time library part 2

    - by b-gen-jack-o-neill
    Hi, I was suggested when I have some further questions on my older ones, to create newer Question and reffer to old one. So, this is the original question: What is the C runtime library? OK, from your answers, I now get thet statically linked libraries are Microsoft implementation of C standart functions. Now: If I get it right, the scheme would be as follow: I want to use printf(), so I must include which just tels compiler there us functio printf() with these parameters. Now, when I compile code, becouse printf() is defined in C Standart Library, and becouse Microsoft decided to name it C Run Time library, it gets automatically statically linked from libcmt.lib (if libcmt.lib is set in compiler) at compile time. I ask, becouse on wikipedia, in article about runtime library there is that runtime library is linked in runtime, but .lib files are linked at compile time, am I right? Now, what confuses me. There is .dll version of C standart library. But I thought that to link .dll file, you must actually call winapi program to load that library. So, how can be these functions dynamically linked, if there is no static library to provide code to tell Windows to load desired functions from dll? And really last question on this subject - are C Standart library functions also calls to winapi even they are not .dll files like more advanced WinAPI functions? I mean, in the end to access framebuffer and print something you must tell Windows to do it, since OS cannot let you directly manipulate HW. I think of it like the OS must be written to support all C standart library functions same way across similiar versions, since they are statically linked, and can differently support more complex WinAPI calls becouse new version of OS can have adjustements in the .dll file.

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  • Case Insensitive Ternary Search Tree

    - by Yan Cheng CHEOK
    I had been using Ternary Search Tree for a while, as the data structure to implement a auto complete drop down combo box. Which means, when user type "fo", the drop down combo box will display foo food football The problem is, my current used of Ternary Search Tree is case sensitive. My implementation is as follow. It had been used by real world for around 1++ yeas. Hence, I consider it as quite reliable. My Ternary Search Tree code However, I am looking for a case insensitive Ternary Search Tree, which means, when I type "fo", the drop down combo box will show me foO Food fooTBall Here are some key interface for TST, where I hope the new case insentive TST may have similar interface too. /** * Stores value in the TernarySearchTree. The value may be retrieved using key. * @param key A string that indexes the object to be stored. * @param value The object to be stored in the tree. */ public void put(String key, E value) { getOrCreateNode(key).data = value; } /** * Retrieve the object indexed by key. * @param key A String index. * @return Object The object retrieved from the TernarySearchTree. */ public E get(String key) { TSTNode<E> node = getNode(key); if(node==null) return null; return node.data; } An example of usage is as follow. TSTSearchEngine is using TernarySearchTree as the core backbone. Example usage of Ternary Search Tree // There is stock named microsoft and MICROChip inside stocks ArrayList. TSTSearchEngine<Stock> engine = TSTSearchEngine<Stock>(stocks); // I wish it would return microsoft and MICROCHIP. Currently, it just return microsoft. List<Stock> results = engine.searchAll("micro");

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  • My cocoa app won't capture key events

    - by Oscar
    Hi, i usually develop for iPhone. But now trying to make a pong game in Cocoa desktop application. Working out pretty well, but i can't find a way to capture key events. Here's my code: #import "PongAppDelegate.h" #define GameStateRunning 1 #define GameStatePause 2 #define BallSpeedX 10 #define BallSpeedY 15 @implementation PongAppDelegate @synthesize window, leftPaddle, rightPaddle, ball; - (void)applicationDidFinishLaunching:(NSNotification *)aNotification { gameState = GameStateRunning; ballVelocity = CGPointMake(BallSpeedX, BallSpeedY); [NSTimer scheduledTimerWithTimeInterval:0.05 target:self selector:@selector(gameLoop) userInfo:nil repeats:YES]; } - (void)gameLoop { if(gameState == GameStateRunning) { [ball setFrameOrigin:CGPointMake(ball.frame.origin.x + ballVelocity.x, ball.frame.origin.y + ballVelocity.y)]; if(ball.frame.origin.x + 15 > window.frame.size.width || ball.frame.origin.x < 0) { ballVelocity.x =- ballVelocity.x; } if(ball.frame.origin.y + 35 > window.frame.size.height || ball.frame.origin.y < 0) { ballVelocity.y =- ballVelocity.y; } } } - (void)keyDown:(NSEvent *)theEvent { NSLog(@"habba"); // Arrow keys are associated with the numeric keypad if ([theEvent modifierFlags] & NSNumericPadKeyMask) { [window interpretKeyEvents:[NSArray arrayWithObject:theEvent]]; } else { [window keyDown:theEvent]; } } - (void)dealloc { [ball release]; [rightPaddle release]; [leftPaddle release]; [super dealloc]; } @end

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  • Relative Paths in .htaccess, how to attach to a variable?

    - by devians
    I have a very heavy htaccess mod_rewrite file that runs my application. As we sometimes take over legacy websites, I sometimes need to support old urls to old files, where my application processes everything post htaccess. My ultimate goal is to have a 'Demilitarized Zone' for old file structures, and use mod rewrite to check for existence there before pushing to the application. This is pretty easy to do with files, by using: RewriteCond %{IS_SUBREQ} true RewriteRule .* - [L] RewriteCond %{ENV:REDIRECT_STATUS} 200 RewriteRule .* - [L] RewriteCond Public/DMZ/$1 -F [OR] RewriteRule ^(.*)$ Public/DMZ/$1 [QSA,L] This allows pseudo support for relative urls by not hardcoding my base path (I cant assume I will ever be deployed in document root) anywhere and using subrequests to check for file existence. Works fine if you know the file name, ie http://domain.com/path/to/app/legacyfolder/index.html However, my legacy urls are typically http://domain.com/path/to/app/legacyfolder/ Mod_Rewrite will allow me to check for this by using -d, but it needs the complete path to the directory, ie RewriteCond Public/DMZ/$1 -F [OR] RewriteCond /var/www/path/to/app/Public/DMZ/$1 -d RewriteRule ^(.*)$ Public/DMZ/$1 [QSA,L] I want to avoid the hardcoded base path. I can see one possible solutions here, somehow determining my path and attaching it to a variable [E=name:var] and using it in the condition. Any implementation that allows me to existence check a directory is more than welcome.

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  • Problem with sorting NSDictionary

    - by Stas Dmitrenko
    Hello. I need to sort a NSDictionary of dictionaries. It looks like: {//dictionary RU = "110.1"; //key and value SG = "150.2"; //key and value US = "50.3"; //key and value } Result need to be like: {//dictionary SG = "150.2"; //key and value RU = "110.1"; //key and value US = "50.3"; //key and value } I am trying this: @implementation NSMutableDictionary (sorting) -(NSMutableDictionary*)sortDictionary { NSArray *allKeys = [self allKeys]; NSMutableArray *allValues = [NSMutableArray array]; NSMutableArray *sortValues= [NSMutableArray array]; NSMutableArray *sortKeys= [NSMutableArray array]; for(int i=0;i<[[self allValues] count];i++) { [allValues addObject:[NSNumber numberWithFloat:[[[self allValues] objectAtIndex:i] floatValue]]]; } [sortValues addObjectsFromArray:allValues]; [sortKeys addObjectsFromArray:[self allKeys]]; [sortValues sortUsingDescriptors:[NSArray arrayWithObject:[[[NSSortDescriptor alloc] initWithKey:@"floatValue" ascending:NO] autorelease]]]; for(int i=0;i<[sortValues count];i++) { [sortKeys replaceObjectAtIndex:i withObject:[allKeys objectAtIndex:[allValues indexOfObject:[sortValues objectAtIndex:i]]]]; [allValues replaceObjectAtIndex:[allValues indexOfObject:[sortValues objectAtIndex:i]] withObject:[NSNull null]]; } NSLog(@"%@", sortKeys); NSLog(@"%@", sortValues); NSLog(@"%@", [NSMutableDictionary dictionaryWithObjects:sortValues forKeys:sortKeys]); return [NSMutableDictionary dictionaryWithObjects:sortValues forKeys:sortKeys]; } @end This is the result of NSLog: 1) { SG, RU, US } 2) { 150.2, 110.1, 50.3 } 3) { RU = "110.1"; SG = "150.2"; US = "50.3"; } Why is this happening? Can you help me with this problem?

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  • How do I get started designing and implementing a script interface for my .NET application?

    - by Peter Mortensen
    How do I get started designing and implementing a script interface for my .NET application? There is VSTA (the .NET equivalent of VBA for COM), but as far as I understand I would have to pay a license fee for every installation of my application. It is an open source application so this will not work. There is also e.g. the embedding of interpreters (IronPython?), but I don't understand how this would allow exposing an "object model" (see below) to external (or internal) scripts. What is the scripting interface story in .NET? Is it somehow trivial in .NET to do this? Background: I have once designed and implemented a fairly involved script interface for a Macintosh application for acquisition and analysis of data from a mass spectrometer (Mac OS, System 7) and later a COM interface for a Windows application. Both were designed with an "object model" and classes (that can have properties). These are overloaded words, but in a scripting interface context object model is essentially a containment hiarchy of objects of specific classes. Classes have properties and lists of contained objects. E.g. like in the COM interfaces exposed in Microsoft Office applications, where the application object can be used to add to its list of documents (with the side effect of creating the GUI representation of a document). External scripts can create new objects in a container and navigate through the content of the hiarchy at any given time. In the Macintosh case scripts could be written in e.g. AppleScript or Frontier. On the Macintosh the implementation of a scripting interface was very complicated. Support for it in Metroworks' C++ class library (the name escapes me right now) made it much simpler.

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  • How can i get rid of 0xFEEFEE in VC

    - by egebilmuh
    Hi guys I m programming C for an assingment in VC++ 2008. I simulate adjList for graph implementation. i can readly add edge between two vertex and print the graph. and i want to remove edge between two vertex and print the graph again. whatever i do,i cant print the graph after deleting the edge. i get 0xfeefee :( what is this? and how can i resolve this program. my delete function and print the graph function are illustrated below. void deleteEdge(Graph G, Vertex V, Vertex W) { Edge list,prev,temp; list=V->list; prev=NULL; // while(list!=NULL && list->to->value!=W->value){ prev=list; list=list->next; } // have found the element. if(list!=NULL){ temp=list; // if first element of list is deleted. if(prev==NULL) list=list->next; else prev->next=list->next; // reallocate. free(temp); } } void GRAPHprint(Graph G) { Vertex tmp; Edge list; for(tmp = G->head;tmp!=NULL;tmp=tmp->next) { fprintf(stdout,"V:%d\t",tmp->value); list=tmp->list; while(list!=NULL) { fprintf(stdout,"%d\t",list->to->value); list=list->next; } fprintf(stdout, "\n"); } system("pause"); }

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  • Resolve php endless recursion issue

    - by Matt
    Hey all, I'm currently running into an endless recursion situation. I'm implementing a message service that calls various object methods.. it's quite similar to observer pattern.. Here's whats going on: Dispatcher.php class Dispatcher { ... public function message($name, $method) { // Find the object based on the name $object = $this->findObjectByName($name); // Slight psuedocode.. for ease of example if($this->not_initialized($object)) $object = new $object(); // This is where it locks up. } return $object->$method(); ... } class A { function __construct() { $Dispatcher->message("B", "getName"); } public function getName() { return "Class A"; } } class B { function __construct() { // Assume $Dispatcher is the classes $Dispatcher->message("A", "getName"); } public function getName() { return "Class B"; } } It locks up when neither object is initialized. It just goes back and forth from message each other and no one can be initialized. I'm looking for some kind of queue implementation that will make messages wait for each other.. One where the return values still get set. I'm looking to have as little boilerplate code in class A and class B as possible Any help would be immensely helpful.. Thanks! Matt Mueller

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  • how to implement a sparse_vector class

    - by Neil G
    I am implementing a templated sparse_vector class. It's like a vector, but it only stores elements that are different from their default constructed value. So, sparse_vector would store the index-value pairs for all indices whose value is not T(). I am basing my implementation on existing sparse vectors in numeric libraries-- though mine will handle non-numeric types T as well. I looked at boost::numeric::ublas::coordinate_vector and eigen::SparseVector. Both store: size_t* indices_; // a dynamic array T* values_; // a dynamic array int size_; int capacity_; Why don't they simply use vector<pair<size_t, T>> data_; My main question is what are the pros and cons of both systems, and which is ultimately better? The vector of pairs manages size_ and capacity_ for you, and simplifies the accompanying iterator classes; it also has one memory block instead of two, so it incurs half the reallocations, and might have better locality of reference. The other solution might search more quickly since the cache lines fill up with only index data during a search. There might also be some alignment advantages if T is an 8-byte type? It seems to me that vector of pairs is the better solution, yet both containers chose the other solution. Why?

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  • Timer Service in ejb 3.1 - schedule calling timeout problem

    - by Greg
    Hi Guys, I have created simple example with @Singleton, @Schedule and @Timeout annotations to try if they would solve my problem. The scenario is this: EJB calls 'check' function every 5 secconds, and if certain conditions are met it will create single action timer that would invoke some long running process in asynchronous fashion. (it's sort of queue implementation type of thing). It then continues to check, but as long as long running process is there it won't start another one. Below is the code I came up with, but this solution does not work, because it looks like asynchronous call I'm making is in fact blocking my @Schedule method. @Singleton @Startup public class GenerationQueue { private Logger logger = Logger.getLogger(GenerationQueue.class.getName()); private List<String> queue = new ArrayList<String>(); private boolean available = true; @Resource TimerService timerService; @Schedule(persistent=true, minute="*", second="*/5", hour="*") public void checkQueueState() { logger.log(Level.INFO,"Queue state check: "+available+" size: "+queue.size()+", "+new Date()); if (available) { timerService.createSingleActionTimer(new Date(), new TimerConfig(null, false)); } } @Timeout private void generateReport(Timer timer) { logger.info("!!--timeout invoked here "+new Date()); available = false; try { Thread.sleep(1000*60*2); // something that lasts for a bit } catch (Exception e) {} available = true; logger.info("New report generation complete"); } What am I missing here or should I try different aproach? Any ideas most welcome :) Testing with Glassfish 3.0.1 latest build - forgot to mention

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  • Collision detections and how efficient they are

    - by Shadow
    How exactly do you implement collision detection? What are the costs involved? Do different platforms(c/c++, java, cocoa/iphone, flash, directX) have different optimizations for calculating collisions. And lastly are there libraries available to do this for me, or some that I can just interpret for my platform of choice? As I understand it you would need to loop through the collision map and find the area in question and then compair the input thing(e.g. a sprite) to the type of pixel that is in the questioned area. I understand the very basic idea, but I don't understand the underlying implementation or even a higher level one for that matter. It would seem that this type of detection, or any for that matter, is very costly. Tile map? Bit array? How are these created from an image(I would guess looping and doing stuff)? The reason I ask this question is to get a better understanding of the efficiency behind the scenes and to understand exactly what is going on. Links, references, or examples would be very helpful. I know this question is a bit longwinded so any help or references would be very welcome. Thanks SO!

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  • How to implement Horner's scheme for multivariate polynomials?

    - by gsreynolds
    Background I need to solve polynomials in multiple variables using Horner's scheme in Fortran90/95. The main reason for doing this is the increased efficiency and accuracy that occurs when using Horner's scheme to evaluate polynomials. I currently have an implementation of Horner's scheme for univariate/single variable polynomials. However, developing a function to evaluate multivariate polynomials using Horner's scheme is proving to be beyond me. An example bivariate polynomial would be: 12x^2y^2+8x^2y+6xy^2+4xy+2x+2y which would factorised to x(x(y(12y+8))+y(6y+4)+2)+2y and then evaluated for particular values of x & y. Research I've done my research and found a number of papers such as: staff.ustc.edu.cn/~xinmao/ISSAC05/pages/bulletins/articles/147/hornercorrected.pdf citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.40.8637&rep=rep1&type=pdf www.is.titech.ac.jp/~kojima/articles/B-433.pdf Problem However, I'm not a mathematician or computer scientist, so I'm having trouble with the mathematics used to convey the algorithms and ideas. As far as I can tell the basic strategy is to turn a multivariate polynomial into separate univariate polynomials and compute it that way. Can anyone help me? If anyone could help me turn the algorithms into pseudo-code that I can implement into Fortran myself, I would be very grateful.

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  • JMF microphone volume controller

    - by TacB0sS
    How to obtain the Microphone volume controller in JMF? this is what I have: I tried this implementation concept of yours, but I keep getting a null from the first volume processor when I try to get the stream, here is how I do it: // the device is the media device specifically audio Processor processorForVolume = Manager.createProcessor(device.getLocator()); // wait until configured ProcessorStates newState = new ProcessorStateListener(Processor.Configured).waitForProcessorState(processorForVolume); System.out.println("volumeProcessorState: "+newState); // setting the content descriptor to null - read in another thread this allows to get the gain control processorForVolume.setContentDescriptor(null); // set the track control format to one supported by the device and the track control. // I didn't match it to an RTP allowed format, but I don't think this has anything to do with it... TrackControl[] trackControls = processorForVolume.getTrackControls(); if (trackControls.length == 0) throw new MC_Exception("No track controls where found for this device:", new Object[]{device}); for (TrackControl control : trackControls) trackManipulator.manipulateTrackControls(control); // wait until the processor is realized newState = new ProcessorStateListener(Controller.Realized).waitForProcessorState(processorForVolume); System.out.println("volumeProcessorState: "+newState); // receives the gain control micVolumeController = processorForVolume.getGainControl(); // cannot get the output stream to process further... any suggestions? processor = Manager.createProcessor(processorForVolume.getDataOutput()); new ProcessorStateListener(Processor.Configured).waitForProcessorState(processor); processor.setContentDescriptor(DeviceCapturingManager.RAW_RTP); new ProcessorStateListener(Controller.Realized).waitForProcessorState(processor); this is the output It generates: volumeProcessorState: Configured format set to track control - com.sun.media.ProcessEngine$ProcTControl@1627c16: LINEAR, 48000.0 Hz, 16-bit, Stereo, LittleEndian, Signed volumeProcessorState: Realized and the data output from the processor is Null. I should make clear that when the content descriptor != null I do get an output stream but not the volume controller, and the when it is null I get the controller, but no stream. I try to connect to an audio microphone device Adam.

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  • Are document-oriented databases any more suitable than relational ones for persisting objects?

    - by Owen Fraser-Green
    In terms of database usage, the last decade was the age of the ORM with hundreds competing to persist our object graphs in plain old-fashioned RMDBS. Now we seem to be witnessing the coming of age of document-oriented databases. These databases are highly optimized for schema-free documents but are also very attractive for their ability to scale out and query a cluster in parallel. Document-oriented databases also hold a couple of advantages over RDBMS's for persisting data models in object-oriented designs. As the tables are schema-free, one can store objects belonging to different classes in an inheritance hierarchy side-by-side. Also, as the domain model changes, so long as the code can cope with getting back objects from an old version of the domain classes, one can avoid having to migrate the whole database at every change. On the other hand, the performance benefits of document-oriented databases mainly appear to come about when storing deeper documents. In object-oriented terms, classes which are composed of other classes, for example, a blog post and its comments. In most of the examples of this I can come up with though, such as the blog one, the gain in read access would appear to be offset by the penalty in having to write the whole blog post "document" every time a new comment is added. It looks to me as though document-oriented databases can bring significant benefits to object-oriented systems if one takes extreme care to organize the objects in deep graphs optimized for the way the data will be read and written but this means knowing the use cases up front. In the real world, we often don't know until we actually have a live implementation we can profile. So is the case of relational vs. document-oriented databases one of swings and roundabouts? I'm interested in people's opinions and advice, in particular if anyone has built any significant applications on a document-oriented database.

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  • How to control the order of module initialization in Prism

    - by Robert Taylor
    I'm using Prism V2 with a DirectoryModuleCatalog and I need the modules to be initialized in a certain order. The desired order is specified with an attribute on each IModule implementation. This is so that as each module is initialized, they add their View into a TabControl region and the order of the tabs needs to be deterministic and controlled by the module author. The order does not imply a dependency, but rather just an order that they should be initialized in. In other words: modules A, B, and C may have priorities of 1, 2, and 3 respectively. B does not have a dependency on A - it just needs to get loaded into the TabControl region after A. So that we have a deterministic and controllable order of the tabs. Also, B might not exist at runtime; so they would load as A, C because the priority should determine the order (1, 3). If i used the ModuleDependency, then module "C" will not be able to load w/o all of it's dependencies. I can manage the logic of how to sort the modules, but i can't figure out where to put said logic.

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  • What are the most time consuming checks performed by .NET when executing a managed appplication?

    - by ltorje
    I've developed a .NET based Windows service that uses part managed (C#) and unmanaged code (C/C++ libraries). In some domain environments (e.g. Win 2k3 32bit server inside domain abc.com) sometimes the service takes more than 30 seconds to start (especially on OS restart), thus failing to start the service. I suspect that it has something to do with enterprise level security but I do not know for sure. http://msdn.microsoft.com/en-us/library/aa720255%28VS.71%29.aspx I've tried the following without success: - delay loading references by moving the using directives as far as possible from the servicebase implementation (especially the xml namespace - know to cause delays in loading) - delay loading and configuring log4net - precompiling the code by using ngen - delaying the start of the worker thread - add/remove manifest + decencies set inside - sign/unsign the binaries - use the configuration settings (there are a lot of settings and the scope level for all is set to application ) as later as possible - add all dependencies to GAC I didn't tried yet to add security demands for the class that has the Main method implemented. I didn't tries to implement my own configuration loader because after inspecting the autogenerated code, I've noticed that the setting class is a singletone and it gets its instance on call. By completely removing the log4net dependency it worked, but this is not an option. When the network card is disabled the service starts immediately. Any suggestions/comments/solution you have would be most welcomed.

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  • Do complex JOINs cause high coupling and maintenance problems ?

    - by ashkan.kh.nazary
    Our project has ~40 tables with complex relations.A colleague believes in using long join queries which enforces me to learn about tables outside of my module but I think I should not concern about tables not directly related to my module and use data access functions (written by those responsible for other modules) when I need data from them. Let me clarify: I am responsible for the ContactVendor module which enables the customers to contact the vendor and start a conversation about some specific product. Products module has it's own complex tables and relations with functions that encapsulate details (for example i18n, activation, product availability etc ...). Now I need to show the product title of some product related to some conversation between the vendor and customers. I may either write a long query that retrieves the product info along with conversation stuff in one shot (which enforces me to learn about Product tables) OR I may pass the relevant product_id to the get_product_info(int) function. First approach is obviously demanding and introduces many bad practices and things I normally consider fault in programming. The problem with the second approach seems to be the countless mini queries these access functions cause and performance loss is a concern when a loop tries to fetch product titles for 100 products using functions that each perform a separate query. So I'm stuck between "don't code to the implementation, code to interface" and performance. What is the right way of doing things ? UPDATE: I'm specially concerned about possible future modifications to those tables outside of my module. What if the Products module decided to change the way they are doing things? or for some reason modify the schema? It means some other modules would break or malfunction until the change is integrated to them. The usual ripple effect problem.

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