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  • What makes the availability of both primitive and object-wrapped values in JavaScript useful?

    - by Delan Azabani
    I wrote a blog post a while ago detailing how the availability of both primitive and object-wrapped value types in JavaScript (for things such as Number, String and Boolean) causes trouble, including but not limited to type-casting to a boolean (e.g. object-wrapped NaN, "" and false actually type-cast to true). My question is, with all this confusion and problems, is there any benefit to JavaScript having both types of values for the built-in classes?

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  • Bracketing algorithm when root finding. Single root in "quadratic" function

    - by Ander Biguri
    I am trying to implement a root finding algorithm. I am using the hybrid Newton-Raphson algorithm found in numerical recipes that works pretty nicely. But I have a problem in bracketing the root. While implementing the root finding algorithm I realised that in several cases my functions have 1 real root and all the other imaginary (several of them, usually 6 or 9). The only root I am interested is in the real one so the problem is not there. The thing is that the function approaches the root like a cubic function, touching with the point the y=0 axis... Newton-Rapson method needs some brackets of different sign and all the bracketing methods I found don't work for this specific case. What can I do? It is pretty important to find that root in my program... EDIT: more problems: sometimes due to reaaaaaally small numerical errors, say a variation of 1e-6 in some value the "cubic" function does NOT have that real root, it is just imaginary with a neglectable imaginary part... (checked with matlab) EDIT 2: Much more information about the problem. Ok, I need root finding algorithm. Info I have: The root I need to find is between [0-1] , if there are more roots outside that part I am not interested in them. The root is real, there may be imaginary roots, but I don't want them. Probably all the rest of the roots will be imaginary The root may be double in that point, but I think that actually doesn't mater in numerical analysis problems I need to use the root finding algorithm several times during the overall calculations, but the function will always be a polynomial In one of the particular cases of the root finding, my polynomial will be similar to a quadratic function that touches Y=0 with the point. Example of a real case: The coefficient may not be 100% precise and that really slight imprecision may make the function not to touch the Y=0 axis. I cannot solve for this specific case because in other cases it may be that the polynomial is pretty normal and doesn't make any "strange" thing. The method I am actually using is NewtonRaphson hybrid, where if the derivative is really small it makes a bisection instead of NewRaph (found in numerical recipes). Matlab's answer to the function on the image: roots: 0.853553390593276 + 0.353553390593278i 0.853553390593276 - 0.353553390593278i 0.146446609406726 + 0.353553390593273i 0.146446609406726 - 0.353553390593273i 0.499999999999996 + 0.000000040142134i 0.499999999999996 - 0.000000040142134i The function is a real example I prepared where I know that the answer I want is 0.5 Note: I still haven't check completely some of the answers I you people have give me (Thank you!), I am just trying to give al the information I already have to complete the question.

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  • changing cell background color in qt

    - by Moayyad Yaghi
    hello .. i'm new to pyqt , and i'm still facing some newbie problems :D i have a QTableWidget that is item delegated on a QChoice control ( hope i said it right ) i need to have the cell background color changes whenever a user change the choice control selection briefly: how to change a cell background color in a table widget ?? i use pyqt4 and python 2.6 thanx in advance

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  • How can I prevent users from overriding the total cost in a shopping cart, when submitted as a hidde

    - by Gobi
    I'm having serious problems with accepting payments. I'm passing the total amount in a hidden field <input type="hidden" name="checkout-flow-support.merchant-checkout-flow-support.shipping-methods.flat-rate-shipping-1.price" value="129.00"/> Some of the users changed this value to 2 using firebug and submitted the form. Instead of getting $129, we only received $2. I have no idea how to proceed this anyone help me quick .

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  • [Haskell]Curious about the Hash Table problem

    - by astamatto
    I read that hash tables in haskell are crippled ( citation: http://flyingfrogblog.blogspot.com/2009/04/more-on-haskells-hash-table-problems.html ) and since i like haskell it worried me. Since the blog-post one year has passed and im curious, The hash table problem in haskell was "fixed" in the traditional compilers? (like ghc) ps: I love stack overflow, im a long time visitor but only today i decided to try to post a question.

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  • A strategy to troubleshoot/ fix application crashes in Windows?

    - by Manav Sharma
    All, Over a period of time I have observed that fixing issues related to application crash is a discipline in itself. Some people have this nice way of attacking such problems. Ranging from Viewing the 'Event Viewer' to running Static/ Dynamic memory analysis tools to some of their 'personal favorites', these people have developed this art. Can we share articles/ links/ personal approaches that we use to understand/ troubleshoot/ fix such issues? Thanks

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  • What is the best way to store incremental downloaded data?

    - by afriza
    Inspired by Chromium's sha1 class, I am thinking to store incrementally downloaded data using std::string // pseudo-code char buff[BUFF_SIZE]; std::string data; do { size = ReadInternetFileTo(buff,BUFF_SIZE); data.append(buff,size); } while (not_finished); Any foreseeable problems with this method or better way to do it?

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  • xml dom node children

    - by matt
    Need some help I've got lots of code and i want to make it shorter i know there's a way but I can't remember it this is code example: <?xml version="1.0" encoding="ISO-8859-1"?> <bookstore> <book category="cooking"> <title lang="en">Everyday Italian</title> <author>Giada De Laurentiis</author> <year>2005</year> <price>30.00</price> </book> <book category="children"> <title lang="en">Harry Potter</title> <author>J K. Rowling</author> <year>2005</year> <price>29.99</price> </book> <book category="web"> <title lang="en">XQuery Kick Start</title> <author>James McGovern</author> <author>Per Bothner</author> <author>Kurt Cagle</author> <author>James Linn</author> <author>Vaidyanathan Nagarajan</author> <year>2003</year> <price>49.99</price> </book> <book category="web" cover="paperback"> <title lang="en">Learning XML</title> <author>Erik T. Ray</author> <year>2003</year> <price>39.95</price> </book> </bookstore As you can see the different nodes, children now is there a way to make this code smaller so I don't have to keep writing the nodes and children

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  • Struggling with ASP.NET MVC auto-scaffolder template

    - by DanM
    I'm trying to write an auto-scaffolder template for Index views. I'd like to be able to pass in a collection of models or view-models (e.g., IQueryable<MyViewModel>) and get back an HTML table that uses the DisplayName attribute for the headings (th elements) and Html.Display(propertyName) for the cells (td elements). Each row should correspond to one item in the collection. Here's what I have so far: <%@ Control Language="C#" Inherits="System.Web.Mvc.ViewUserControl" %> <% var items = (IQueryable<TestProj.ViewModels.TestViewModel>)Model; // How do I make this generic? var properties = items.First().GetMetadata().Properties .Where(pm => pm.ShowForDisplay && !ViewData.TemplateInfo.Visited(pm)); %> <table> <tr> <% foreach(var property in properties) { %> <th> <%= property.DisplayName %> </th> <% } %> </tr> <% foreach(var item in items) { HtmlHelper itemHtml = ????; // What should I put in place of "????"? %> <tr> <% foreach(var property in properties) { %> <td> <%= itemHtml.Display(property.DisplayName) %> </td> <% } %> </tr> <% } %> </table> Two problems with this: I'd like it to be generic. So, I'd like to replace var items = (IQueryable<TestProj.ViewModels.TestViewModel>)Model; with var items = (IQueryable<T>)Model; or something to that effect. A property Html is automatically created for me when the view is created, but this HtmlHelper applies to the whole collection. I need to somehow create an itemHtml object that applies just to the current item in the foreach loop. I'm not sure how to do this, however, because the constructors for HtmlHelper don't take a Model object. How do I solve these two problems?

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  • jquery chekbox selected

    - by Dejan.S
    Hi I'm having some problems with jquery checkbox selected. I want to do a task when the checkbox is selected. my code for this is $(document).ready(function() { if ($('#chxGetText').is(':checked')) { alert("OK"); } }); <input id="chxGetText" type="checkbox" /> But nothing happen when I check the checkbox. Any ideas?

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  • Working through exercises in "Cocoa Programming for Mac OS X" - I'm stumped

    - by Zigrivers
    I've been working through the exercises in a book recommended here on stackoverflow, however I've run into a problem and after three days of banging my head on the wall, I think I need some help. I'm working through the "Speakline" exercise where we add a TableView to the interface and the table will display the "voices" that you can choose for the text to speech aspect of the program. I am having two problems that I can't seem to get to the bottom of: I get the following error: * Illegal NSTableView data source (). Must implement numberOfRowsInTableView: and tableView:objectValueForTableColumn:row: The tableView that is supposed to display the voices comes up blank I have a feeling that both of these problems are related. I'm including my interface code here: #import <Cocoa/Cocoa.h> @interface AppController : NSObject <NSSpeechSynthesizerDelegate, NSTableViewDelegate> { IBOutlet NSTextField *textField; NSSpeechSynthesizer *speechSynth; IBOutlet NSButton *stopButton; IBOutlet NSButton *startButton; IBOutlet NSTableView *tableView; NSArray *voiceList; } - (IBAction)sayIt:(id)sender; - (IBAction)stopIt:(id)sender; @end And my implementation code here: #import "AppController.h" @implementation AppController - (id)init { [super init]; //Log to help me understand what is happening NSLog(@"init"); speechSynth = [[NSSpeechSynthesizer alloc] initWithVoice:nil]; [speechSynth setDelegate:self]; voiceList = [[NSSpeechSynthesizer availableVoices] retain]; return self; } - (IBAction)sayIt:(id)sender { NSString *string = [[textField stringValue] stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]]; //Is the string zero-length? if([string length] == 0) { NSLog(@"String from %@ is a string with a length of %d.", textField, [string length]); [speechSynth startSpeakingString:@"Please enter a phrase first."]; } [speechSynth startSpeakingString:string]; NSLog(@"Started to say: %@", string); [stopButton setEnabled:YES]; [startButton setEnabled:NO]; } - (IBAction)stopIt:(id)sender { NSLog(@"Stopping..."); [speechSynth stopSpeaking]; } - (void) speechSynthesizer:(NSSpeechSynthesizer *)sender didFinishSpeaking:(BOOL)complete { NSLog(@"Complete = %d", complete); [stopButton setEnabled:NO]; [startButton setEnabled:YES]; } - (NSInteger)numberOfRowsInTableView:(NSTableView *)aTableView { return [voiceList count]; } - (id)tableView: (NSTableView *)tv objecValueForTableColumn: (NSTableColumn *)tableColumn row:(NSInteger)row { NSString *v = [voiceList objectAtIndex:row]; NSLog(@"v = %@",v); NSDictionary *dict = [NSSpeechSynthesizer attributesForVoice:v]; return [dict objectForKey:NSVoiceName]; } /* - (BOOL)respondsToSelector:(SEL)aSelector { NSString *methodName = NSStringFromSelector(aSelector); NSLog(@"respondsToSelector: %@", methodName); return [super respondsToSelector:aSelector]; } */ @end Hopefully, you guys can see something obvious that I've missed. Thank you!

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  • Launch another instance of Java app on Mac

    - by TomA
    I have a Mac Java app bundle that has problems opening an OpenGL window from a SWT dialog in a single process. It just doesn't work. To solve this problem I would like to open a SWT dialog in one instance of the Java app and then have it launch another instance of itself with a parameter saying "this time open the OpenGL window". The part I don't know how to do is finding out what "itself" is on a Mac. How can I do that?

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  • two UserControls, one page, need to notify each other of updates

    - by jeriley
    I've got a user control thats used twice on the same page, each have the ability to be updated (a dropdown list gets a new item) and I'm not sure what might be the best way to handle this. One concern - this is an older system (~4+ years, datasets, .net2) and it is amazingly brittle. I did manage to have it run on 3.5 with no problems, but I've had a few run-ins with the javascript validation (~300 lines per page) throwing up all over the place when I change/add/modify controls in the parent.

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  • Software Architecture: Unit of Work design pattern discussion

    - by santiagobasulto
    Hey everybody. According Martin Fowler's Unit of Work description: "Maintains a list of objects that are affected by a business transaction and coordinates the writing out of changes and resolution of concurrency problems." Avoiding very small calls to the database, which ends up being very slow I'm wondering. If we just delimit it to database transaction management, won't prepare statements help with this?

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  • Where to #include?

    - by fuzzygoat
    In my past applications I have been #importing into my *.h files where needed. I have not really thought much about this before as I have not had any problems, but today I spotted something that got me to thinking that maybe I should be #import-ing into my .m files and using @class where needed in the headers (.h) Can anyone shine any light on the way its supposed to be done or best practice? gary

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  • Sanity Check: change event not firing first time using keyboard

    - by macca1
    I've done a good amount of research on this and found a bunch of reported problems and solutions but the general consensus seems that all change problems in IE6 were fixed in jQuery 1.4.2. I'm having an issue where a change event is not firing in jQuery 1.4.2, but it did fire successfully in jQuery 1.3.2. This is in IE6. I'm about to submit a bug for this, but for my sanity I wanted to post it here first to see if there's something dumb I'm missing. I don't understand why this is working this way... <HTML> <HEAD> <TITLE>jQuery 1.4.2 Problem </TITLE> <script src="jquery-1.4.2.min.js" type="text/javascript"></script> <script> $(document).ready( function() { $("#firstBox").change(function() { alert("CHANGE"); }); // ONLOAD of document autofocus into the first element... $("form").find(":input:visible:first").focus() }); </script> </HEAD> <BODY> <form> <select id="firstBox"> <option value="" selected="selected">--</option> <option value="1">One</option> <option value="2">Two</option> </select> <br><br> <input size="10" id="secondBox"> </form> </BODY> </HTML> Simple enough, right? Onload of the page, give the first element focus. Onchange of the first element, alert. If you use the mouse, it works as expected. The page loads, the focus is in the drop down, you change the option, you get the alert. The problem is if you use the keyboard. The page loads, the focus is in the drop down, you press the down arrow. The option changes. Tab off the field, no alert. Weird. To make it even weirder, if you tab back into the field and change it again (all using the keyboard), the change event DOES fire after tab out this time. Any ideas?

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  • Broadcast receiver, check status, turning off connection with F8

    - by yoann
    I am using eclipse with android sdk 3.2 I have some problems to make my broadcast receiver working when the connection is lost. first I have checked the type of network to make sure I understand well : ConnectivityManager manager = (ConnectivityManager) getSystemService(CONNECTIVITY_SERVICE); boolean is3g = manager.getNetworkInfo( ConnectivityManager.TYPE_MOBILE) .isConnectedOrConnecting(); boolean isWifi = manager.getNetworkInfo( ConnectivityManager.TYPE_WIFI) .isConnectedOrConnecting(); NetworkInfo info = manager.getActiveNetworkInfo(); if (info != null) Toast.makeText(getApplicationContext(), info.getTypeName(), Toast.LENGTH_LONG).show(); else Toast.makeText(getApplicationContext(), "Pas de connexion", Toast.LENGTH_LONG).show(); if (!is3g) Log.i("Network Listener", "DISCONNECTED"); else Log.i("Network Listener", "CONNECTED"); == this is a mobile network, I'm connected Then I press F8 or I make : telnet localhost 5554 gsm data off to stop the connection Here is my dynamic broadcast receiver in an activity : public class ActivityA extends Activity { @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.query); this.registerReceiver(this.networkStateReceiver, new IntentFilter( ConnectivityManager.CONNECTIVITY_ACTION)); } BroadcastReceiver networkStateReceiver = new BroadcastReceiver() { @Override public void onReceive(Context context, Intent intent) { ConnectivityManager connMgr = (ConnectivityManager) context .getSystemService(Context.CONNECTIVITY_SERVICE); NetworkInfo networkInfo = connMgr.getActiveNetworkInfo(); //i have tried several things : State networkState = networkInfo.getState(); // if (networkState.compareTo(State.DISCONNECTED) == 0) ... if (networkInfo != null && networkInfo.isConnected()) { Toast.makeText(getApplicationContext(), "CONNECTED", Toast.LENGTH_LONG).show(); Log.i("Network Listener", "Connected"); } else { Toast.makeText(getApplicationContext(), "DISCONNECTED", Toast.LENGTH_LONG).show(); Log.i("Network Listener", "Network Type Changed"); Intent offline = new Intent(AccountInfoActivity.this, OfflineWorkService.class); startService(offline); } }; My manifest : <uses-permission android:name="android.permission.INTERNET" /> <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/> The problem is : when the activityA is launched, my broadcast receive something and it displays "Connected"(Log) and my toast. When I turn off the connection manually, nothing happend. My service is not started, log message are not displayed, only toast messages work ... And even better, when I turn on the connection again (by pressing F8), I test again the type of connection, Toast messages are shown but this time Log messages don't work. Problems happend when I press F8. Anyway, I think I miss something with broadcast receivers, it's not totally clear. Please help me.

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  • Android multi-touch support

    - by Zdenek F
    Hi, I wonder if is the Android multi-touch support reliable? I've read it suffers from some problems. I also wonder, how can I define custom multi-touch gestures? Like: 3 fingers rotate or 3 fingers stay static and fourth is moving. I've come across some resources (Gestures or MotionEvent on developer.android.com) but nothing states it clearly. Regards, Zdenek

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