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  • Variable length argument list - How to understand we retrieved the last argument?

    - by hkBattousai
    I have a Polynomial class which holds coefficients of a given polynomial. One of its overloaded constructors is supposed to receive these coefficients via variable argument list. template <class T> Polynomial<T>::Polynomial(T FirstCoefficient, ...) { va_list ArgumentPointer; va_start(ArgumentPointer, FirstCoefficient); T NextCoefficient = FirstCoefficient; std::vector<T> Coefficients; while (true) { Coefficients.push_back(NextCoefficient); NextCoefficient = va_arg(ArgumentPointer, T); if (/* did we retrieve all the arguments */) // How do I implement this? { break; } } m_Coefficients = Coefficients; } I know that we usually pass an extra parameter which tells the recipient method the total number of parameters, or we pass a sentimental ending parameter. But in order to keep thing short and clean, I don't prefer passing an extra parameter. Is there any way of doing this without modifying the method signature in the example?

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  • Double null-terminated string

    - by wengseng
    I need to format a string to be double null-terminated string in order to use SHFileOperation. Interesting part is i found one of the following working, but not both: // Example 1 CString szDir(_T("D:\\Test")); szDir = szDir + _T('\0') + _T('\0'); // Example 2 CString szDir(_T("D:\\Test")); szDir = szDir + _T("\0\0"); //Delete folder SHFILEOPSTRUCT fileop; fileop.hwnd = NULL; // no status display fileop.wFunc = FO_DELETE; // delete operation fileop.pFrom = szDir; // source file name as double null terminated string fileop.pTo = NULL; // no destination needed fileop.fFlags = FOF_NOCONFIRMATION|FOF_SILENT; // do not prompt the user fileop.fAnyOperationsAborted = FALSE; fileop.lpszProgressTitle = NULL; fileop.hNameMappings = NULL; int ret = SHFileOperation(&fileop); Does anyone has idea on this? Is there other way to append double-terminated string?

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  • Does Interlocked guarantee visibility to other threads in C# or do I still have to use volatile?

    - by Lirik
    I've been reading the answer to a similar question, but I'm still a little confused... Abel had a great answer, but this is the part that I'm unsure about: ...declaring a variable volatile makes it volatile for every single access. It is impossible to force this behavior any other way, hence volatile cannot be replaced with Interlocked. This is needed in scenarios where other libraries, interfaces or hardware can access your variable and update it anytime, or need the most recent version. Does Interlocked guarantee visibility of the atomic operation to all threads, or do I still have to use the volatile keyword on the value in order to guarantee visibility of the change? Here is my example: public class CountDownLatch { private volatile int m_remain; // <--- do I need the volatile keyword there since I'm using Interlocked? private EventWaitHandle m_event; public CountDownLatch (int count) { Reset(count); } public void Reset(int count) { if (count < 0) throw new ArgumentOutOfRangeException(); m_remain = count; m_event = new ManualResetEvent(false); if (m_remain == 0) { m_event.Set(); } } public void Signal() { // The last thread to signal also sets the event. if (Interlocked.Decrement(ref m_remain) == 0) m_event.Set(); } public void Wait() { m_event.WaitOne(); } }

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  • What's the use of writing tests matching configuration-like code line by line?

    - by Pascal Van Hecke
    Hi, I have been wondering about the usefulness of writing tests that match code one-by-one. Just an example: in Rails, you can define 7 restful routes in one line in routes.rb using: resources :products BDD/TDD proscribes you test first and then write code. In order to test the full effect of this line, devs come up with macros e.g. for shoulda: http://kconrails.com/2010/01/27/route-testing-with-shoulda-in-ruby-on-rails/ class RoutingTest < ActionController::TestCase # simple should_map_resources :products end I'm not trying to pick on the guy that wrote the macros, this is just an example of a pattern that I see all over Rails. I'm just wondering what the use of it is... in the end you're just duplicating code and the only thing you test is that Rails works. You could as well write a tool that transforms your test macros into actual code... When I ask around, people answer me that: "the tests should document your code, so yes it makes sense to write them, even if it's just one line corresponding to one line" What are your thoughts?

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  • S.redirectTo leads always to a blank screen

    - by Jaime Ocampo
    I am now playing a little bit with lift (2.8.0), and all the features in LiftRules work as intended. But I haven't been able to use S.redirectTo at all. I always ends with a blank screen, no matter what. No error messages at all! As an example, I have the following form: ... <lift:logIn.logInForm form="post"> <p><login:name /></p> <p><login:password /></p> <p><login:submit /></p> </lift:logIn.logInForm> ... And the code is: object LogIn extends helper.LogHelper { ... def logInForm(in: NodeSeq): NodeSeq = { var name = "" var password = "" def login() = { logger.info("name: " + name) logger.info("password: " + password) if (name == "test1") S.redirectTo("/example") if (name == "test2") S.redirectTo("/example.html") if (name == "test3") S.redirectTo("example.html") S.redirectTo("/") } bind("login", in, "name" -> SHtml.text(name, name = _), "password" -> SHtml.password(password, password = _), "submit" -> SHtml.submit("Login", login)) } } The method 'login' is invoked, I can check that in the log information. But as I said, no matter which name I enter, I always end with a blank screen, although 'examples.html' is available when being accessed directly in the browser. How should I invoke S.redirectoTo in order to navigate to 'examples.html'? Also, why don't I receive an error message (I am logging at a debug level)? I think all the configuration in Boot is correct, since all LitRules examples (statelessRewrite, dispatch, viewDispatch, snippets) work fine.

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  • Why is this Javascript that writes out a Google Ad not displaying properly on the iPhone?

    - by Dave M G
    I have this Javacsript code that checks to see if there is a DIV named "google-ad", and if there is, it writes in a the necessary code to display the Google Ad. This works great in browsers like Firefox, Chrome, Safari on Mac, and Android. However, when I bundle this code with Adobe's Phonegap Build, and deploy it to iPhones, it behaves strangely. It launches a browser window displaying just the Google Ad alone. In order to keep using my app, every time I change a page and a new Google Ad is loaded, I have to close the browser window to get back to the app. Why is this code launching browser windows outside of my Phonegap app on iPhone? if(document.getElementById("google-ad") && document.getElementById("google-ad") !== null && document.getElementById("google-ad") !== "undefined") { if(userStatus.status == 0) { document.getElementById("centre").style.padding = "137px 0 12px 0"; document.getElementById("header-container").style.margin = "-138px 0 0 0"; document.getElementById("header-container").style.height = "132px"; document.getElementById("header-username").style.top = "52px"; document.getElementById("google-ad").style.height = "50px"; document.getElementById("google-ad").style.width = "320px"; document.getElementById("google-ad").style.backgroundColor = "#f0ebff"; document.getElementById("google-ad").style.display = "block"; window["google_ad_client"] = 'ca-pub-0000000000000000'; window["google_ad_slot"] = "00000000"; window["google_ad_width"] = 320; window["google_ad_height"] = 50; window.adcontainer = document.getElementById('google-ad'); window.adhtml = ''; function mywrite(html) { adhtml += html; adcontainer.innerHTML = adhtml; }; document.write_ = document.write; document.write = mywrite; script = document.createElement('script'); script.src='http://pagead2.googlesyndication.com/pagead/show_ads.js'; script.type='text/javascript'; document.body.appendChild(script); }

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  • Why doesn't this PHP execute?

    - by cam
    I copied the code from this site exactly: http://davidwalsh.name/web-service-php-mysql-xml-json as follows, /* require the user as the parameter */ if(isset($_GET['user']) && intval($_GET['user'])) { /* soak in the passed variable or set our own */ $number_of_posts = isset($_GET['num']) ? intval($_GET['num']) : 10; //10 is the default $format = strtolower($_GET['format']) == 'json' ? 'json' : 'xml'; //xml is the default $user_id = intval($_GET['user']); //no default /* connect to the db */ $link = mysql_connect('localhost','username','password') or die('Cannot connect to the DB'); mysql_select_db('db_name',$link) or die('Cannot select the DB'); /* grab the posts from the db */ $query = "SELECT post_title, guid FROM wp_posts WHERE post_author = $user_id AND post_status = 'publish' ORDER BY ID DESC LIMIT $number_of_posts"; $result = mysql_query($query,$link) or die('Errant query: '.$query); /* create one master array of the records */ $posts = array(); if(mysql_num_rows($result)) { while($post = mysql_fetch_assoc($result)) { $posts[] = array('post'=>$post); } } /* output in necessary format */ if($format == 'json') { header('Content-type: application/json'); echo json_encode(array('posts'=>$posts)); } else { header('Content-type: text/xml'); echo '<posts>'; foreach($posts as $index => $post) { if(is_array($post)) { foreach($post as $key => $value) { echo '<',$key,'>'; if(is_array($value)) { foreach($value as $tag => $val) { echo '<',$tag,'>',htmlentities($val),'</',$tag,'>'; } } echo '</',$key,'>'; } } } echo '</posts>'; } /* disconnect from the db */ @mysql_close($link); } And the php doesn't execute, it just displays as plain text. What's the dealio? The host supports PHP, I use it to run a Wordpress blog and other things.

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  • please check my MYSQL query & give me advice?

    - by Suba
    select s.s_nric as NRIC,s.s_name as NAME,s.s_psle_eng as PSLE_ENG,s.s_psle_math as PSLE_MATHS,s.s_psle_aggr as PSLE_AGGR, (SELECT re.re_mark FROM si_results re WHERE re.re_code like 'FEEN%' AND re.re_year='2008' AND re.re_semester='2' AND re.re_nric=s.s_nric ) as English_2008, (SELECT re.re_mark FROM si_results re WHERE re.re_code like 'FEMA%' AND re.re_year='2008' AND re.re_semester='2' AND re.re_nric=s.s_nric ) Maths_2008, (SELECT re.re_mark FROM si_results re WHERE re.re_code like 'FEEN%' AND re.re_year='2009' AND re.re_semester='2' AND re.re_nric=s.s_nric ) as English_2009, (SELECT re.re_mark FROM si_results re WHERE re.re_code like 'FEMA%' AND re.re_year='2009' AND re.re_semester='2' AND re.re_nric=s.s_nric ) Maths_2009 ,isc.isc_g_gpa as ISC_GPA from si_student_data as s LEFT JOIN si_isc_gpa as isc ON isc.isc_g_nric=s.s_nric where 1=1 AND s.s_admission_year='2008' GROUP BY s.s_nric ORDER BY s.s_gender,s.s_name asc This is my query. please check my sub query this is my sub query (SELECT re.re_mark FROM si_results re WHERE re.re_code like 'FEEN%' AND re.re_year='2008' AND re.re_semester='2' AND re.re_nric=s.s_nric ) as English_2008, (SELECT re.re_mark FROM si_results re WHERE re.re_code like 'FEMA%' AND re.re_year='2008' AND re.re_semester='2' AND re.re_nric=s.s_nric ) Maths_2008, (SELECT re.re_mark FROM si_results re WHERE re.re_code like 'FEEN%' AND re.re_year='2009' AND re.re_semester='2' AND re.re_nric=s.s_nric ) as English_2009, (SELECT re.re_mark FROM si_results re WHERE re.re_code like 'FEMA%' AND re.re_year='2009' AND re.re_semester='2' AND re.re_nric=s.s_nric ) Maths_2009 When I execute my query, server take long time to execute. So how to make simple? please advice me. Thanks.

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  • System Calls in windows & Native API?

    - by claws
    Recently I've been using lot of Assembly language in *NIX operating systems. I was wondering about the windows domain. Calling convention in linux: mov $SYS_Call_NUM, %eax mov $param1 , %ebx mov $param2 , %ecx int $0x80 Thats it. That is how we should make a system call in linux. Reference of all system calls in linux: Regarding which $SYS_Call_NUM & which parameters we can use this reference : http://docs.cs.up.ac.za/programming/asm/derick_tut/syscalls.html OFFICIAL Reference : http://kernel.org/doc/man-pages/online/dir_section_2.html Calling convention in Windows: ??? Reference of all system calls in Windows: ??? Unofficial : http://www.metasploit.com/users/opcode/syscalls.html , but how do I use these in assembly unless I know the calling convention. OFFICIAL : ??? If you say, they didn't documented it. Then how is one going to write libc for windows without knowing system calls? How is one gonna do Windows Assembly programming? Atleast in the driver programming one needs to know these. right? Now, whats up with the so called Native API? Is Native API & System calls for windows both are different terms referring to same thing? In order to confirm I compared these from two UNOFFICIAL Sources System Calls: http://www.metasploit.com/users/opcode/syscalls.html Native API: http://undocumented.ntinternals.net/aindex.html My observations: All system calls are beginning with letters Nt where as Native API is consisting of lot of functions which are not beginning with letters Nt. System Call of windows are subset of Native API. System calls are just part of Native API. Can any one confirm this and explain.

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  • Managing StringBuilder Resources

    - by Jim Fell
    My C# (.NET 2.0) application has a StringBuilder variable with a capacity of 2.5MB. Obviously, I do not want to copy such a large buffer to a larger buffer space every time it fills. By that point, there is so much data in the buffer anyways, removing the older data is a viable option. Can anyone see any obvious problems with how I'm doing this (i.e. am I introducing more performance problems than I'm solving), or does it look okay? tText_c = new StringBuilder(2500000, 2500000); private void AppendToText(string text) { if (tText_c.Length * 100 / tText_c.Capacity > 95) { tText_c.Remove(0, tText_c.Length / 2); } tText_c.Append(text); } EDIT: Additional information: In this application new data is received very rapidly (on the order of milliseconds) through a serial connection. I don't want to populate the multiline textbox with this new information so frequently because that kills the performance of the application, so I'm saving it to a StringBuilder. Every so often, the application copies the contents of the StringBuilder to the textbox and wipes out the StringBuilder contents.

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  • what is the best way to optimize my json on an asp.net-mvc site

    - by ooo
    i am currently using jqgrid on an asp.net mvc site and we have a pretty slow network (internal application) and it seems to be taking the grid a long time to load (the issue is both network as well as parsing, rendering) I am trying to determine how to minimized what i send over to the client to make it as fast as possible. Here is a simplified view of my controller action to load data into the grid: [AcceptVerbs(HttpVerbs.Get)] public ActionResult GridData1(GridData args) { var paginatedData = applications.GridPaginate(args.page ?? 1, args.rows ?? 10, i => new { i.Id, Name = "<div class='showDescription' id= '" + i.id+ "'>" + i.Name + "</div>", MyValue = GetImageUrl(_map, i.value, "star"), ExternalId = string.Format("<a href=\"{0}\" target=\"_blank\">{1}</a>", Url.Action("Link", "Order", new { id = i.id }), i.Id), i.Target, i.Owner, EndDate = i.EndDate, Updated = "<div class='showView' aitId= '" + i.AitId + "'>" + GetImage(i.EndDateColumn, "star") + "</div>", }) return Json(paginatedData); } So i am building up a json data (i have about 200 records of the above) and sending it back to the GUI to put in the jqgrid. The one thing i can thihk of is Repeated data. In some of the json fields i am appending HTML on top of the raw "data". This is the same HTML on every record. It seems like it would be more efficient if i could just send the data and "append" the HTML around it on the client side. Is this possible? Then i would just be sending the actual data over the wire and have the client side add on the rest of the HTML tags (the divs, etc) be put together. Also, if there are any other suggestions on how i can minimize the size of my messages, that would be great. I guess at some point these solution will increase the client side load but it may be worth it to cut down on network traffic.

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  • Help dealing with data dependency between two registration forms

    - by franko75
    I have a tricky issue here with a registration of both a user and his/her pet. Both the user and the pet are treated as separate entities and both require separate registration forms. However, the user's pet has to be linked to the user via a foreign key in the database. The process is basically that when a new user joins the site, firstly they register their pet, then they register themselves. The reason for this order is to check their pet's eligibility for the site (there are some criteria to be met) first, instead of getting the user to sign up only to then find out their pet is ineligible. It is this ordering of the form submissions which is causing me a bit of a headache, as follows... The site is being developed with an MVC framework, and the User registration process is managed via a method in a User_form controller, while the pet registration process is managed via a method in the Pet_form controller. The pet registration form happens first, and the pet data can be saved without the owner_id at this stage, with the user id possibly being added (e.g by retrieving pet's id from session) following user registration. However, doing it this way could potentially result in redundant data, where pet records would be created in the database, but if the user doesn't actually register themselves too, then the pets will be ownerless records in the DB. Other option is to serialize the new pet's data at the pet registration stage, don't save it to the DB until the user fills out their registration form. Once the user is created, i can pass serialised data AND the owner_id to a method in the Pet Model which can update the DB. However, I also need to set the newly created $pet to $this-pet which I then access for a sequence of other related forms. Should I just set the session variable in the model method? Then in the Pet controller constructor, do a check for pet stored in session, if yes, assign to $this-pet... If this makes any sense to anybody and you have some advice, i'd be grateful to hear it!

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  • in Rails, with check_box_tag, how do I keep the checkboxes checked after submitting query?

    - by Sebastien Paquet
    Ok, I know this is for the Saas course and people have been asking questions related to that as well but i've spent a lot of time trying and reading and I'm stuck. First of all, When you have a model called Movie, is it better to use Ratings as a model and associate them or just keep Ratings in an array floating in space(!). Second, here's what I have now in my controller: def index @movies = Movie.where(params[:ratings].present? ? {:rating => (params[:ratings].keys)} : {}).order(params[:sort]) @sort = params[:sort] @ratings = Ratings.all end Now, I decided to create a Ratings model since I thought It would be better. Here's my view: = form_tag movies_path, :method => :get do Include: - @ratings.each do |rating| = rating.rating = check_box_tag "ratings[#{rating.rating}]" = submit_tag "Refresh" I tried everything that is related to using a conditional ternary inside the checkbox tag ending with " .include?(rating) ? true : "" I tried everything that's supposed to work but it doesn't. I don't want the exact answer, I just need guidance.Thanks in advance!

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  • How can I make hundreds of simultaneously running processes communicate with a database through one

    - by Olfan
    Long speech short: How can I make hundreds of simultaneously running processes communicate with a database through one or few permanent sessions? The whole story: I once built a number crunching engine that handles vast amounts of large data files by forking off one child after another giving each a small number of files to work on. File locking, progress monitoring and result propagation happen in an Oracle database which all (sub-)processes access at various times using an application-specific module which encapsulates DBI. This worked well at first, but now with higher volumes of input data, the number of database sessions (one per child, and they can be very short-lived) constantly being opened and closed is becoming an issue. I now want to centralise database access so that there are only one or few fixed database sessions which handle all database access for all the (sub-)processes. The presence of the database abstraction module should make the changes easy because the function calls in the worker instances can stay the same. My problem is that I cannot think of a suitable way to enhance said module in order to establish communication between all the processes and the database connector(s). I thought of message queueing, but couldn't come up with a way of connecting a large herd of requestors with one or few database connectors in a way so that bidirectional communication is possible (for collecting the query result). An asynchronous approach could help here in that all requests are written to the same queue and the database connector servicing the request will "call back" to submit the result. But my mind fails me in generating an image clear enough so that I can paint into code. Threading instead of forking might have given me an easier start, but this would now require massive changes to the code base that I'm not prepared to do to a live system. The more I think of it, the more the base idea looks like a pre-forked web server to me only that it doesn't serve web pages but database queries. Any ideas on what to dig into, and where? Sample (pseudo) code to inspire me, links to possibly related articles, ready solutions on CPAN maybe?

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  • C++ destructor problem with boost::scoped_ptr

    - by bb-generation
    I have a question about the following code: #include <iostream> #include <boost/scoped_ptr.hpp> class Interface { }; class A : public Interface { public: A() { std::cout << "A()" << std::endl; } virtual ~A() { std::cout << "~A()" << std::endl; } }; Interface* get_a() { A* a = new A; return a; } int main() { { std::cout << "1" << std::endl; boost::scoped_ptr<Interface> x(get_a()); std::cout << "2" << std::endl; } std::cout << "3" << std::endl; } It creates the following output: 1 A() 2 3 As you can see, it doesn't call the destructor of A. The only way I see to get the destructor of A being called, is to add a destructor for the Interface class like this: virtual ~Interface() { } But I really want to avoid any Implementation in my Interface class and virtual ~Interface() = 0; doesn't work (produces some linker errors complaining about a non existing implementation of ~Interface(). So my question is: What do I have to change in order to make the destructor being called, but (if possible) leave the Interface as an Interface (only abstract methods).

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  • Gradual memory leak and slowdown in loop

    - by Benji XVI
    I have a simple foundation tool that exports every frame of a movie as a .tiff file. Here is the relevant code: NSString* movieLoc = [NSString stringWithCString:argv[1]]; QTMovie *sourceMovie = [QTMovie movieWithFile:movieLoc error:nil]; int i=0; while (QTTimeCompare([sourceMovie currentTime], [sourceMovie duration]) != NSOrderedSame) { // save image of movie to disk NSAutoreleasePool *arp = [[NSAutoreleasePool alloc] init]; NSString *filePath = [NSString stringWithFormat:@"/somelocation_%d.tiff", i++]; NSData *currentImageData = [[sourceMovie currentFrameImage] TIFFRepresentation]; [currentImageData writeToFile:filePath atomically:NO]; NSLog(@"%@", filePath); [sourceMovie stepForward]; [arp release]; } [pool drain]; return 0; As you can see, in order to prevent very large memory buildups with the various transparently-autoreleased variables in the loop, we create, and flush, an autoreleasepool with every run through the loop. However, over the course of stepping through a movie, the amount of memory used by the program still gradually increases, and the speed at which frames are processed drops precipitously. (From ~0.5 seconds per frame at the start, to ~2 seconds per frame by the 250th frame.) The only thing I can think can be causing the gradual memory leak is a buildup of the NSAutoreleasePool objects themselves. Am I right in thinking they will only be deallocated when the outer pool is released? If so, is there a better memory management solution here? Creating a pool every run through the loop seems a little hacky. And if not, what is causing the slow memory leak? (It is not NSStrings, and much too slow to be NSImages or NSDatas.) And what could be causing the slowdown?

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  • What is Wordpress doing for content encoding in it's mysql database?

    - by qbxk
    For some convoluted reasons best left behind us, I require direct access the contents of a wordpress database. I'm using mysql 5.0.70-r1 on gentoo with wordpress 2.6, and perl 5.8.8 ftr. So, sometimes we get high-order characters in the blog, we have quite a few authors contributing too, for the most part these characters end up in wp's database in wp_posts.post_content or wp_postmeta.meta_value, Wordpress is displaying these correctly on it's site, but the database stores it using single byte encoding that I can't figure out how to convert to the correct string. Today's example: the blog shows this, and doesn't even seem to escape any chars in the html, Hãhãhães but the database, when viewed via the mysql prompt, has, Hãhãhães So clearly this is some kind of double-byte encoding issue, but I don't know how I can correct it. I need to be able to pull that second string from the database (b/c that's what it gives me) and convert it to the first one, and i need to do so using perl. also, just to help unmuddy any waters, I took these strings and printed out the ascii codes for each character using perl's ord() function. Here is the output of the "wrong" string H = 72 à = 195 £ = 163 h = 104 à = 195 £ = 163 h = 104 à = 195 £ = 163 e = 101 s = 115 This is the correct string, that I need to produce in my script H = 72 ã = 227 h = 104 ã = 227 h = 104 ã = 227 e = 101 s = 115

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  • Can FFT length affect filtering accuracy?

    - by Charles
    Hi, I am designing a fractional delay filter, and my lagrange coefficient of order 5 h(n) have 6 taps in time domain. I have tested to convolute the h(n) with x(n) which is 5000 sampled signal using matlab, and the result seems ok. When I tried to use FFT and IFFT method, the output is totally wrong. Actually my FFT is computed with 8192 data in frequency domain, which is the nearest power of 2 for 5000 signal sample. For the IFFT portion, I convert back the 8192 frequency domain data back to 5000 length data in time domain. So, the problem is, why this thing works in convolution, but not in FFT multiplication. Does converting my 6 taps h(n) to 8192 taps in frequency domain causes this problem? Actually I have tried using overlap-save method, which perform the FFT and multiplication with smaller chunks of x(n) and doing it 5 times separately. The result seems slight better than the previous, and at least I can see the waveform pattern, but still slightly distorted. So, any idea where goes wrong, and what is the solution. Thank you.

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  • SQL Server race condition issue with range lock

    - by Freek
    I'm implementing a queue in SQL Server (please no discussions about this) and am running into a race condition issue. The T-SQL of interest is the following: set transaction isolation level serializable begin tran declare @RecordId int declare @CurrentTS datetime2 set @CurrentTS=CURRENT_TIMESTAMP select top 1 @RecordId=Id from QueuedImportJobs with (updlock) where Status=@Status and (LeaseTimeout is null or @CurrentTS>LeaseTimeout) order by Id asc if @@ROWCOUNT> 0 begin update QueuedImportJobs set LeaseTimeout = DATEADD(mi,5,@CurrentTS), LeaseTicket=newid() where Id=@RecordId select * from QueuedImportJobs where Id = @RecordId end commit tran RecordId is the PK and there is also an index on Status,LeaseTimeout. What I'm basically doing is select a record of which the lease happens to be expired, while simultaneously updating the lease time with 5 minutes and setting a new lease ticket. So the problem is that I'm getting deadlocks when I run this code in parallel using a couple of threads. I've debugged it up to the point where I found out that the update statement sometimes gets executing twice for the same record. Now, I was under the impression that the with (updlock) should prevent this (it also happens with xlock btw, not with tablockx). So it actually look like there is a RangeS-U and a RangeX-X lock on the same range of records, which ought to be impossible. So what am I missing? I'm thinking it might have something to do with the top 1 clause or that SQL Server does not know that where Id=@RecordId is actually in the locked range? Deadlock graph: Table schema (simplified):

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  • Can you recommend an easy to use easy to develop CMS?

    - by el_at_yahoo
    We need some easy way to manage web sites at our company, and we are evaluating some CMS tools for this purpose. We do not yet know what features the sites will need to have (but it will definitely be something with lots of functionalities), so we are looking for something with lots of features and more importantly to be easily extensible (if it does not have some feature, we at least want to be able to build-it by ourselves). We have no experience with Content Management Systems but we do with Java, so it has to be something written in Java. We evaluated some tools and from our perspective the following seem the promising of them (in no particular order): OpenCMS dotCMS (Community Edition vs Enterprise Edition) InfoGlue Alfresco (EE vs CE) Magnolia (EE vs EE Pro vs CE) Jahia (CE vs EE) Since we have no experience with either one of them, we were wondering if someone of you who have can share some information about how good they are or how easily they can be used and extended. I know similar questions have been asked on SO and I also know this is highly subjective and people will vote for closing it as soon as it is posted, but for us it is important to know what difficulties other people have been facing in using the above tools (we don’t want to walk a path that takes nowhere if other people already know it leads nowhere). Others could then vote on the posted answers if they agree or not. From your experience, which from the above mentioned CMSs is the more easily extensible, the easier to use, the easiest to learn etc? Thank you and Happy Holidays to all.

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  • C# Type conversion between two similar Datatable objects

    - by Ali
    I have .NET project with sync framework and two separate Datasets for MS SQL and Compact SQL. in my base class I have a generic DataTable object. in my derived classed I assign Typed DataTable to the generic object based on whether the application is operating online or offline: example: if (online) _dataTable = new MSSQLDataSet.Customer; else _dataTable = new CompactSQLDataSet.Customer; Now every where in my code i have to check and do a cast based on the current network mode like this: public void changeCustomerID(int ID) { if (online) (MSSQLDataSet.CustomerDataTable)_dataTable)[i].CustomerID = value; else (CompactMSSQLDataSet.CustomerDataTable)_dataTable)[i].CustomerID = value; } but I don't think this is very efficient and I believe it can be done in a smarter way to only use one line of code by dynamically getting the Type of _dataTable on the run time. my problem is at the design time, in order to acess datatable porperties such as "CustomerID" it has to be casted to either MSSQLDataSet.CustomerDataTable or CompactMSSQLDataSet.CustomerDataTable. Is there a way to have a function or a operator to convert the _datatable to its runtime type but still be able to use it's design time properties which are the same between the two types? something like: ((aType)_dataTable)[i].CustomerID = value; //or GetRuntimeType(_dataTable)[i].CustomerID = value;

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  • Cocoa NSTextField Drag & Drop Requires Subclass... Really?

    - by ipmcc
    Until today, I've never had occasion to use anything other than an NSWindow itself as an NSDraggingDestination. When using a window as a one-size-fits-all drag destination, the NSWindow will pass those messages on to its delegate, allowing you to handle drops without subclassing NSWindow. The docs say: Although NSDraggingDestination is declared as an informal protocol, the NSWindow and NSView subclasses you create to adopt the protocol need only implement those methods that are pertinent. (The NSWindow and NSView classes provide private implementations for all of the methods.) Either a window object or its delegate may implement these methods; however, the delegate’s implementation takes precedence if there are implementations in both places. Today, I had a window with two NSTextFields on it, and I wanted them to have different drop behaviors, and I did not want to allow drops anywhere else in the window. The way I interpret the docs, it seems that I either have to subclass NSTextField, or make some giant spaghetti-conditional drop handlers on the window's delegate that hit-checks the draggingLocation against each view in order to select the different drop-area behaviors for each field. The centralized NSWindow-delegate-based drop handler approach seems like it would be onerous in any case where you had more than a small handful of drop destination views. Likewise, the subclassing approach seems onerous regardless of the case, because now the drop handling code lives in a view class, so once you accept the drop you've got to come up with some way to marshal the dropped data back to the model. The bindings docs warn you off of trying to drive bindings by setting the UI value programmatically. So now you're stuck working your way back around that too. So my question is: "Really!? Are those the only readily available options? Or am I missing something straightforward here?" Thanks.

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  • summing functions handles in matlab

    - by user552231
    Hi I am trying to sum two function handles, but it doesn't work. for example: y1=@(x)(x*x); y2=@(x)(x*x+3*x); y3=y1+y2 The error I receive is "??? Undefined function or method 'plus' for input arguments of type 'function_handle'." This is just a small example, in reality I actually need to iteratively sum about 500 functions that are dependent on each other. EDIT The solution by Clement J. indeed works but I couldn't manage to generalize this into a loop and ran into a problem. I have the function s=@(x,y,z)((1-exp(-x*y)-z)*exp(-x*y)); And I have a vector v that contains 536 data points and another vector w that also contains 536 data points. My goal is to sum up s(v(i),y,w(i)) for i=1...536 Thus getting one function in the variable y which is the sum of 536 functions. The syntax I tried in order to do this is: sum=@(y)(s(v(1),y,z2(1))); for i=2:536 sum=@(y)(sum+s(v(i),y,z2(i))) end

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  • C# "Rename" Property in Derived Class

    - by Eric
    When you read this you'll be awfully tempted to give advice like "this is a bad idea for the following reason..." Bear with me. I know there are other ways to approach this. This question should be considered trivia. Lets say you have a class "Transaction" that has properties common to all transactions such as Invoice, Purchase Order, and Sales Receipt. Let's take the simple example of Transaction "Amount", which is the most important monetary amount for a given transaction. public class Transaction { public double Amount { get; set; } public TxnTypeEnum TransactionType { get; set; } } This Amount may have a more specific name in a derived type... at least in the real world. For example, the following values are all actually the same thing: Transaction - Amount Invoice - Subtotal PurchaseOrder - Total Sales Receipt - Amount So now I want a derived class "Invoice" that has a Subtotal rather than the generically-named Amount. Ideally both of the following would be true: In an instance of Transaction, the Amount property would be visible. In an instance of Invoice, the Amount property would be hidden, but the Subtotal property would refer to it internally. Invoice looks like this: public class Invoice : Transaction { new private double? Amount { get { return base.Amount; } set { base.Amount = value; } } // This property should hide the generic property "Amount" on Transaction public double? SubTotal { get { return Amount; } set { Amount = value; } } public double RemainingBalance { get; set; } } But of course Transaction.Amount is still visible on any instance of Invoice. Thanks for taking a look!

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  • Database locking: ActiveRecord + Heroku

    - by JP
    I'm building a Sinatra based app for deployment on Heroku. You can imagine it like a standard URL shortener but where old shortcodes expire and become available for new URLs (I realise this is a silly concept but its easier to explain this way). I'm representing the shortcode in my database as an integer and redefining its reader to give a nice short and unique string from the integer. As some rows will be deleted, I've written code that goes thru all the shortcode integers and picks the first free one to use just before_save. Unfortunately I can make my code create two rows with identical shortcode integers if I run two instances very quickly one after another, which is obviously no good! How should I implement a locking system so that I can quickly save my record with a unique shortcode integer? Here's what I have so far: Chars = ('a'..'z').to_a + ('A'..'Z').to_a + ('0'..'9').to_a CharLength = Chars.length class Shorts < ActiveRecord::Base before_save :gen_shortcode after_save :done_shortcode def shortcode i = read_attribute(:shortcode).to_i return '0' if i == 0 s = '' while i > 0 s << Chars[i.modulo(CharLength)] i /= 62 end s end private def gen_shortcode shortcode = 0 self.class.find(:all,:order=>"shortcode ASC").each do |s| if s.read_attribute(:shortcode).to_i != shortcode # Begin locking? break end shortcode += 1 end write_attribute(:shortcode,shortcode) end def done_shortcode # End Locking? end end

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