Search Results

Search found 7324 results on 293 pages for 'operations research'.

Page 225/293 | < Previous Page | 221 222 223 224 225 226 227 228 229 230 231 232  | Next Page >

  • Problem Binding a ObservableCollection to a ListBox in WPF/MVVM

    - by alexqs
    I'm working in some code , using wpf and starting to use mvvm. So far i have no problem, when i have one element and I have to show the values of it in the screen (binding of the specific name of the property). But now, i have to work with a property list , not knowing the names of it. So I created a class, named GClass, that only have two propierties, name and value. I created the ObservableCollection, and fill for now with direct values, and asign the view (lstview) datacontext with the object i have created. But I cant see any result, it always shows a blank listbox. Can someone tell me if see why is happening ? Code of c# VDt = new ObservableCollection<GClass>(); var vhDt = message.SelectSingleElement(typeof (Vh)) as Vehiculo; if(vhDt != null) { VDt.Add(new GClass() {Name = "Numero: ", Value = ""}); VDt.Add(new GClass() {Name = "Marca: ", Value = ""}); VDt.Add(new GClass() {Name = "Conductor: ", Value = ""}); lstview.DataContext = this; _regionManager.RegisterViewWithRegionInIndex(RegionNames.MainRegion, lstview, 0); Code of the view <ListBox Margin="5,5,5,25" ItemsSource="{Binding VDt}"> <ListBox.Template> <ControlTemplate> <ListViewItem Content="{Binding Name}"></ListViewItem> <ListViewItem Content="{Binding Value}"></ListViewItem> </ControlTemplate> </ListBox.Template> </ListBox> I have research here, but i cant see, what I'm doing wrong. I will apreciate if someone help me.

    Read the article

  • Bitwise Interval Arithmetic

    - by KennyTM
    I've recently read an interesting thread on the D newsgroup, which basically asks, Given two signed integers a ∈ [amin, amax], b ∈ [bmin, bmax], what is the tightest interval of a | b? I'm think if interval arithmetics can be applied on general bitwise operators (assuming infinite bits). The bitwise-NOT and shifts are trivial since they just corresponds to -1 − x and 2n x. But bitwise-AND/OR are a lot trickier, due to the mix of bitwise and arithmetic properties. Is there a polynomial-time algorithm to compute the intervals of bitwise-AND/OR? Note: Assume all bitwise operations run in linear time (of number of bits), and test/set a bit is constant time. The brute-force algorithm runs in exponential time. Because ~(a | b) = ~a & ~b and a ^ b = (a | b) & ~(a & b), solving the bitwise-AND and -NOT problem implies bitwise-OR and -XOR are done. Although the content of that thread suggests min{a | b} = max(amin, bmin), it is not the tightest bound. Just consider [2, 3] | [8, 9] = [10, 11].)

    Read the article

  • Can I use a plaintext diff algorithm for tracking XML changes?

    - by rinogo
    Hi all! Interesting question for you here. I'm working in Flex/AS3 on (for simplicity) an XML editor. I need to provide undo/redo functionality. Of course, one solution is to store the entire source text with each edit. However, to conserve memory, I'd like to store the diffs instead (these diffs will also be used to transmit updates to the server for auto-saving). My question is - can I use a plaintext diff algorithm for tracking these XML changes? My research on the internet indicates that I cannot do so. However, I'm obviously missing something. Plaintext diff provides functionality that is purportedly: diff(text, text') - diffs patch(text, diffs) - text' XML is simply text, so why can't I just use diff() and patch() to transform the text reliably? For example: Let's say that I'm a poet. When I write poetry, I use lots of funky punctuation... You know, like <, /, and . (You might see where I'm going with this...) If I'm writing my poetry in an application that uses diffs to provide undo/redo functionality, does my poetry become garbled when I undo/redo my edits? It's just text! Why does it make a difference to the algorithm? I obviously don't get something here...Thanks for explaining! :) -Rich

    Read the article

  • Why isn’t my autoreleased object getting released?

    - by zoul
    Hello. I am debugging a weird memory management error and I can’t figure it out. I noticed that some of my objects are staying in memory longer than expected. I checked all my memory management and finally got to the very improbable conclusion that some of my autorelease operations don’t result in a release. Under what circumstances is that possible? I created a small testing Canary class that logs a message in dealloc and have the following testing code in place: NSLog(@"On the main thread: %i.", [NSThread isMainThread]); [[[Canary alloc] init] autorelease]; According to the code we’re really on the main thread, but the dealloc in Canary does not get called until much later. The delay is not deterministic and can easily take seconds or more. How is that possible? The application runs on a Mac, the garbage collection is turned off (Objective-C Garbage Collection is set to Unsupported on the target.) I am mostly used to iOS, is memory management on OS X different in some important way?

    Read the article

  • UX question: is better to have "serious delete" or have "trash"

    - by ftrotter
    I am developing an application that allows for a user to manage some individual data points. One of the things that my users will want to do is "delete" but what should that mean? For a web application is it better to present a user with the option to have serious delete or to use a "trash" system? Under "serious delete" (would love to know if there is a better name for this...) you click "delete" and then the user is warned "this is final and tragic action. Once you do this you will not be able to get -insert data point name here- back, even if you are crying..." Then if they click delete... well it truly is gone forever. Under the "trash" model, you never trust that the user really wants to delete... instead you remove the data point from the "main display" and put into a bucket called "the trash". This gets it out of the users way, which is what they usually want, but they can get it back if they make a mistake. Obviously this is the way most operating systems have gone. The advantages of "serious delete" are: Easy to implement Easy to explain to users The disadvantages of "serious delete" are: it can be tragically final sometimes, cats walk on keyboards The advantages of the "trash" system are: user is safe from themselves bulk methods like "delete a bunch at once" make more sense saves support headaches The disadvantages of the "trash" system are": For sensitive data, you create an illusion of destruction users think something is gone, but it is not. Lots of subtle distinctions make implementation more difficult Do you "eventually" delete the contents of the trash? My question is which one is the right design pattern for modern web applications? With enough discussion to justify your answer... Would love to be pointed towards some relevant research. -FT

    Read the article

  • how to include .pl (PERL) file in PHP

    - by dexter
    i have two pages one in php(index.php) and another one in Perl(dbcon.pl). basically i want my php file to show only the UI and all the data operations would be done in Perl file. i have tried in index.pl <?php include("dbcon.pl");?> <html> <br/>PHP</br> </html> and dbcon.pl has #!/usr/bin/perl use strict; use warnings; use DBI; use CGI::Simple; my $cgi = CGI::Simple->new; my $dsn = sprintf('DBI:mysql:database=%s;host=%s','dbname','localhost'); my $dbh = DBI->connect($dsn,root =>'',{AutoCommit => 0,RaisError=> 0}); my $sql= "SELECT * FROM products"; my $sth =$dbh->prepare($sql); $sth->execute or die "SQL Error: $DBI::errstr\n"; while (my @row = $sth->fetchrow_array){ print $cgi->header, <<html; <div>&nbsp;@row[0]&nbsp;@row[1]&nbsp;@row[2]&nbsp;@row[3]&nbsp;@row[4]</div> html } but when i run index.php in browser it prints all the code in dbcon.pl file instead of executing it how to overcome this problem? note: i am running this in windows environment is there any other way to do this?

    Read the article

  • Displaying ppt, doc, and xls in UIWebView doesn't work but pdf does

    - by slugolicious
    It looks like a few people on stackoverflow get this to work but their code isn't posted. I'm using [web loadData:data MIMEType:MIMEType textEncodingName:@"UTF-8" baseURL:nil]; where MIMEType is: @"application/vnd.ms-powerpoint" @"application/vnd.ms-word" @"application/vnd.ms-excel" (BTW, I've seen DOC files use mimetype @"application/msword" but the "vnd" version seems more appropriate. I tried both just in case.) I verified that my 'data' is correct. PDF and TXT files work. When the UIWebView displays PPT, DOC, or XLS files, it's blank. I put NSLOG statements in my UIWebViewDelegate calls. shouldStartLoadWithRequest:<NSMutableURLRequest about:blank> navType:5 webViewDidStartLoad: didFailLoadWithError:Error Domain=NSURLErrorDomain Code=100 UserInfo=0x122503a0 "Operation could not be completed. (NSURLErrorDomain error 100.)" didFailLoadWithError:Error Domain=WebKitErrorDomain Code=102 UserInfo=0x12253840 "Frame load interrupted" so obviously the load is failing, but why? If I change my mimetype to @"text/plain" for a PPT file, the UIWebView loads fine and displays unprintable characters, as expected. That's telling me the 'data' passed to loadData: is ok. Meaning my mimetypes are bad? And just to make sure my PPT, DOC, and XLS files are indeed ok to display, I created a simple html file with anchor tags to the files. When the html file is displayed in Safari on the iPhone, clicking on the files displays correctly in Safari. I tried to research the error code displayed in didFailLoadWithError (100) but all the documented error codes are negative and greater than 1000 (as seen in NSURLError.h). -(void)webView:(UIWebView *)webView didFailLoadWithError:(NSError *)error { NSLog(@"didFailLoadWithError:%@", error); }

    Read the article

  • Eclipse Plug-In Installation Issues

    - by Mudu
    Hi all I'm beginning to work with Eclipse for some Java development. I'm quite new to Eclipse, as I am a Visual Studio developer normally. I tried to install the CheckStyle Eclipse Plug-In and Subversive, using the Eclipse "Install new Software" feature. No errors, everything seems to have worked well. Clicking on "What software is already installed?" in the Install-dialogue shows me a list of installed plug-ins. Both Subversive and CheckStyle for Eclipse are listed. My only problem is that neither of them "work", that means I cannot see any new UI elements. According to the manual I have, I should see a new node "CheckStyle" in a project's properties. I haven't. I don't know exactly what Subversive looks like, but I'm sure there's a way to conveniently perform check-out operations etc. Manually copying the downloaded plug-in to the dropins-folder and restarting Eclipse subsequently does not help either. Is there a way to reliably find out whether there occurred any errors - I have no error message at all, what drives me crazy and makes the problem pretty difficult to describe/Google... Any help would be very cool! Cheers Matthias

    Read the article

  • Question about Multicast Delegates?

    - by IbrarMumtaz
    I am going through some exam questions for the 70-536 exam and an actual question one developer posted on his blog has popped up in my exam questions. I cannot remember what his answer was .... but below is the question: You need to write a multicast delegate that accepts a DateTime argument and returns a bool value. Which code segment should you use? A: public delegate int PowerDeviceOn(bool, DateTime) B: public delegate bool PowerDeviceOn(Object, EventArgs) C: public delegate void PowerDeviceOn(DateTime) D: public delegate bool PowerDeviceOn(DateTime) The answer is A. Can someone please explain why? As I already did some research into this question a while ago and so I was sure that it was C, obviously now looking back at the question its clear that I did not read properly. As i was sure I had seen the same one before so I jumped to the most obvious one. A variation on this question: You need to write a multicast delegate that accepts a DateTime argument. Which code segment should you use? A: public delegate int PowerDeviceOn(bool, DateTime) B: public delegate bool PowerDeviceOn(Object, EventArgs) C: public delegate void PowerDeviceOn(DateTime) D: public delegate bool PowerDeviceOn(DateTime) Now this is another variation on this question, it still has the same bogus sample answers, as they still kind work in throwing the exam taker off. Notice how by simply keeping the sample answers the same and by removing a small portion of the question text, the answer is C and not A. The variation has no official answer as I just conjured it up using the exam question as a baseplate. The answer is definitely C. This time round its easy to see why C is correct but the very first question I have an inkling but as you know an inkling is not good enough in passing exams. Thanks For Reading.

    Read the article

  • What is your best-practice advice on implementing SQL stored procedures (in a C# winforms applicatio

    - by JYelton
    I have read these very good questions on SO about SQL stored procedures: When should you use stored procedures? and Are Stored Procedures more efficient, in general, than inline statements on modern RDBMS’s? I am a beginner on integrating .NET/SQL though I have used basic SQL functionality for more than a decade in other environments. It's time to advance with regards to organization and deployment. I am using .NET C# 3.5, Visual Studio 2008 and SQL Server 2008; though this question can be regarded as language- and database- agnostic, meaning that it could easily apply to other environments that use stored procedures and a relational database. Given that I have an application with inline SQL queries, and I am interested in converting to stored procedures for organizational and performance purposes, what are your recommendations for doing so? Here are some additional questions in my mind related to this subject that may help shape the answers: Should I create the stored procedures in SQL using SQL Management Studio and simply re-create the database when it is installed for a client? Am I better off creating all of the stored procedures in my application, inside of a database initialization method? It seems logical to assume that creating stored procedures must follow the creation of tables in a new installation. My database initialization method creates new tables and inserts some default data. My plan is to create stored procedures following that step, but I am beginning to think there might be a better way to set up a database from scratch (such as in the installer of the program). Thoughts on this are appreciated. I have a variety of queries throughout the application. Some queries are incredibly simple (SELECT id FROM table) and others are extremely long and complex, performing several joins and accepting approximately 80 parameters. Should I replace all queries with stored procedures, or only those that might benefit from doing so? Finally, as this topic obviously requires some research and education, can you recommend an article, book, or tutorial that covers the nuances of using stored procedures instead of direct statements?

    Read the article

  • MySQL Full-Text Search Across Multiple Tables - Quick/Long Solution?

    - by Kerry
    Hello all, I have been doing a bit of research on full-text searches as we realized a series of LIKE statements are terrible. My first find was MySQL full-text searches. I tried to implement this and it worked on one table, failed when I was trying to join multiple tables, and so I consulted stackoverflow's articles (look at the end for a list of the ones I've been to) I didn't see anything that clearly answered my questions. I'm trying to get this done literally in an hour or two (quick solution) but I also want to do a better long term solution. Here is my query: SELECT a.`product_id`, a.`name`, a.`slug`, a.`description`, b.`list_price`, b.`price`, c.`image`, c.`swatch`, e.`name` AS industry FROM `products` AS a LEFT JOIN `website_products` AS b ON (a.`product_id` = b.`product_id`) LEFT JOIN ( SELECT `product_id`, `image`, `swatch` FROM `product_images` WHERE `sequence` = 0) AS c ON (a.`product_id` = c.`product_id`) LEFT JOIN `brands` AS d ON (a.`brand_id` = d.`brand_id`) INNER JOIN `industries` AS e ON (a.`industry_id` = e.`industry_id`) WHERE b.`website_id` = 96 AND b.`status` = 1 AND b.`active` = 1 AND MATCH( a.`name`, a.`sku`, a.`description`, d.`name` ) AGAINST ( 'ashley sofa' ) GROUP BY a.`product_id` ORDER BY b.`sequence` LIMIT 0, 9 The error I get is: Incorrect arguments to MATCH If I remove d.name from the MATCH statement it works. I have a full-text index on that column. I saw one of the articles say to use an OR MATCH for this table, but won't that lose the effectiveness of being able to rank them together or match them properly? Other places said to use UNIONs but I don't know how to do that properly. Any advice would be greatly appreciated. In the idea of a long term solution it seems that either Sphinx or Lucene is best. Now by no means and I a MySQL guru, and I heard that Lucene is a bit more complicated to setup, any recommendations or directions would be great. Articles: http://stackoverflow.com/questions/1117005/mysql-full-text-search-across-multiple-tables http://stackoverflow.com/questions/668371/mysql-fulltext-search-across-1-table http://stackoverflow.com/questions/2378366/mysql-how-to-make-multiple-table-fulltext-search http://stackoverflow.com/questions/737275/pros-cons-of-full-text-search-engine-lucene-sphinx-postgresql-full-text-searc http://stackoverflow.com/questions/1059253/searching-across-multiple-tables-best-practices

    Read the article

  • Login to website using PHP and get text from page

    - by Anthony Garand
    I am trying to login to a website and grab content from a page you must be authenticated to see. I have done some research and have seen some examples using both cURL and stream_context_create but I cannot get either way to work. I have the url for the page to login to, and the page that contains the data I need to get. Your help is much appreciated! Here's what I'm working with: <?php $pages = array('home' => 'https://www.53.com/wps/portal/personal', 'login' => 'https://www.53.com/wps/portal/personal', 'data' => 'https://www.53.com/servlet/efsonline/index.html?Messages.SortedBy=DATE,REVERSE'); $ch = curl_init(); //Set options for curl session $options = array(CURLOPT_USERAGENT => 'Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.0)', CURLOPT_SSL_VERIFYPEER => FALSE, CURLOPT_SSL_VERIFYHOST => 2, CURLOPT_HEADER => TRUE, //CURLOPT_RETURNTRANSFER => TRUE, CURLOPT_COOKIEFILE => 'cookie.txt', CURLOPT_COOKIEJAR => 'cookies.txt'); //Hit home page for session cookie $options[CURLOPT_URL] = $pages['home']; curl_setopt_array($ch, $options); curl_exec($ch); //Login $options[CURLOPT_URL] = $pages['login']; $options[CURLOPT_POST] = TRUE; $options[CURLOPT_POSTFIELDS] = 'uid-input=xxx&pw=xxx'; $options[CURLOPT_FOLLOWLOCATION] = FALSE; curl_setopt_array($ch, $options); curl_exec($ch); //Hit data page $options[CURLOPT_URL] = $pages['data']; curl_setopt_array($ch, $options); $data = curl_exec($ch); //Output data echo $data; //Close curl session curl_close($ch); ?> Cheers, Anthony

    Read the article

  • Would OpenID or OAuth work for authorization/authentication on a distributed web service?

    - by David Eyk
    We're in the early stages of designing a RESTful/resource-oriented web service API for a computational lingustics application. Because many of the resources we plan to serve are rights-encumbered, a key design decision has been to specify the platform so that each resource provider can expose their own web service that complies with the API spec. This way, the rights owner maintains control over their content (and thus the ability to throttle or deny access at will) and a direct relationship with the consumer, while still being able to participate in in the collaborative network. At the same time, to simplify the job of writing a client for this service, we want to allow a client access to the distributed service through one end-point, with the server handling content negotiation and retrieval from the appropriate providers. Right now, we're at an impasse on authentication/authorization schemes. One of our number has argued for the (technical) simplicity of a central authentication registry, but others are concerned about the organizational complexity of such a scheme. It seems to me, based on an albeit limited understanding of the technologies, that a combination of OpenID and OAuth would do the trick, with a client authenticating with the end-point via OpenID, and the server taking action on the user's behalf with the various content providers using OAuth. I've only ever seen implementations (e.g. stackoverflow, twitter, etc.) where a human was present to intervene, and I still need to do more research on these technologies. Would a scheme like this work for an automated web service, or would it make the client too difficult to implement and operate?

    Read the article

  • nasm/yasm arguments, linkage to C++

    - by arionik
    Hello everybody, I've got a question concerning nasm and its linkage to C++. I declare a litte test function as extern "C" void __cdecl myTest( byte i1, byte i2, int stride, int *width ); and I call it like this: byte i1 = 1, i2 = 2; int stride = 3, width = 4; myTest( i1, i2, stride, &width ); the method only serves to debug assembly and have a look at how the stack pointer is used to get the arguments. beyond that, the pointer arguments value shall be set to 7, to figure out how that works. This is implemented like this: global _myTest _myTest: mov eax, [esp+4] ; 1 mov ebx, [esp+8] ; 2 mov ecx, dword [esp+16] ; width mov edx, dword [esp+12] ; stride mov eax, dword [esp+16] mov dword [eax], 7 ret and compiled via yasm -f win32 -g cv8 -m x86 -o "$(IntDir)\$(InputName).obj" "$(InputPath)" , then linked to the c++ app. In debug mode, everything works fine. the function is called a couple of times and works as expected, whereas in release mode the function works once, but subsequent programm operations fail. It seems to me that something's wrong with stack/frame pointers, near/far, but I'm quite new to this subject and need a little help. thanks in advance! a.

    Read the article

  • Scalable / Parallel Large Graph Analysis Library?

    - by Joel Hoff
    I am looking for good recommendations for scalable and/or parallel large graph analysis libraries in various languages. The problems I am working on involve significant computational analysis of graphs/networks with 1-100 million nodes and 10 million to 1+ billion edges. The largest SMP computer I am using has 256 GB memory, but I also have access to an HPC cluster with 1000 cores, 2 TB aggregate memory, and MPI for communication. I am primarily looking for scalable, high-performance graph libraries that could be used in either single or multi-threaded scenarios, but parallel analysis libraries based on MPI or a similar protocol for communication and/or distributed memory are also of interest for high-end problems. Target programming languages include C++, C, Java, and Python. My research to-date has come up with the following possible solutions for these languages: C++ -- The most viable solutions appear to be the Boost Graph Library and Parallel Boost Graph Library. I have looked briefly at MTGL, but it is currently slanted more toward massively multithreaded hardware architectures like the Cray XMT. C - igraph and SNAP (Small-world Network Analysis and Partitioning); latter uses OpenMP for parallelism on SMP systems. Java - I have found no parallel libraries here yet, but JGraphT and perhaps JUNG are leading contenders in the non-parallel space. Python - igraph and NetworkX look like the most solid options, though neither is parallel. There used to be Python bindings for BGL, but these are now unsupported; last release in 2005 looks stale now. Other topics here on SO that I've looked at have discussed graph libraries in C++, Java, Python, and other languages. However, none of these topics focused significantly on scalability. Does anyone have recommendations they can offer based on experience with any of the above or other library packages when applied to large graph analysis problems? Performance, scalability, and code stability/maturity are my primary concerns. Most of the specialized algorithms will be developed by my team with the exception of any graph-oriented parallel communication or distributed memory frameworks (where the graph state is distributed across a cluster).

    Read the article

  • Problems with zend-tool reporting that providers are not valid

    - by Mario
    I have recently setup XAMPP 1.7.3 and ZendFramework 1.10.4 on a new computer and many of the commands that I normally use now fail. Here are the steps I used to setup and test ZF. First I added the ZF library folder (C:\xampp\php\ZendFramework-1.10.4\library) to the include path in php.ini. Then I added the ZF bin folder (C:\xampp\php\ZendFramework-1.10.4\bin) to my Path system variable. To test that everything is configured correctly I ran the command "zf show version" from the command line. The result is "Zend Framework Version: 1.9.6". Immediately something appears to be wrong. The file that is downloaded is "ZendFramework-1.10.4.zip" and the reported version is 1.9.6. I have re-downloaded the latest version (1.10.4) and removed old copy. Still the incorrect version number problem persisted. Having done some research there is a bug in the ZF knowledgebase that version 1.10.3 reports a wrong version number. So that may explain the version number problem. Moving forward I tried to run some zf-tool commands and certain commands reports that the action or provider is not valid. Example: C:\xampp\htdocs>zf create project test Creating project at C:/xampp/htdocs/test C:\xampp\htdocs>cd test C:\xampp\htdocs\test>zf create controller Test Creating a controller at C:\xampp\htdocs\test/application/controllers/TestController.php ... Updating project profile 'C:\xampp\htdocs\test/.zfproject.xml' C:\xampp\htdocs\test>zf create action test Test Creating an action named test inside controller at C:\xampp\htdocs\test/application/controllers/TestController.php ... Updating project profile 'C:\xampp\htdocs\test/.zfproject.xml' C:\xampp\htdocs\test>zf enable layout An Error Has Occurred Action 'enable' is not a valid action. ... C:\xampp\htdocs\test>zf create form Test An Error Has Occurred Provider 'form' is not a valid provider. ... Can any one provide insight into these errors and how to correct them?

    Read the article

  • Asynchronously populate datagridview in Windows Forms application

    - by dcryptd
    howzit! I'm a web developer that has been recently requested to develop a Windows forms application, so please bear with me (or dont laugh!) if my question is a bit elementary. After many sessions with my client, we eventually decided on an interface that contains a tabcontrol with 5 tabs. Each tab has a datagridview that may eventually hold up to 25,000 rows of data (with about 6 columns each). I have successfully managed to bind the grids when the tab page is loaded and it works fine for a few records, but the UI freezes when I bound the grid with 20,000 dummy records. The "freeze" occurs when I click on the tab itself, and the UI only frees up (and the tab page is rendered) once the bind is complete. I communicated this to the client and mentioned the option of paging for each grid, but she is adament w.r.t. NOT wanting this. My only option then is to look for some asynchronous method of doing this in the background. I don't know much about threading in windows forms, but I know that I can use the BackgroundWorker control to achieve this. My only issue after reading up a bit on it is that it is ideally used for "long-running" tasks and I/O operations. My questions: How does one determine a long-running task? How does one NOT MISUSE the BackgroundWorker control, ie. is there a general guideline to follow when using this? (I understand that opening/spawning multiple threads may be undesirable in certain instances) Most importantly: How can I achieve (asychronously) binding of the datagridview after the tab page - and all its child controls - loads. Thank you for reading this (ahem) lengthy query, and I highly appreciate any responses/thoughts/directions on this matter! Cheers!

    Read the article

  • theoretical and practical matrix multiplication FLOP

    - by mjr
    I wrote traditional matrix multiplication in c++ and tried to measure and compare its theoretical and practical FLOP. As I know inner loop of MM has 2 operation therefore simple MM theoretical Flops is 2*n*n*n (2n^3) but in practice I get something like 4n^3 + number of operation which is 2 i.e. 6n^3 also if I just try to add up only one array a[i][j]++ practical flops then calculate like 3n^3 and not n^3 as you see again it is 2n^3 +1 operation and not 1 operation * n^3 . This is in case if I use 1D array in three nested loops as Matrix multiplication and compare flop, practical flop is the same (near) the theoretical flop and depend exactly as the number of operation in inner loop.I could not find the reason for this behaviour. what is the reason in both case? I know that theoretical flop is not the same as practical one because of some operations like load etc. system specification: Intel core2duo E4500 3700g memory L2 cache 2M x64 fedora 17 sample results: Matrix matrix multiplication 512*512 Real_time: 1.718368 Proc_time: 1.227672 Total flpops: 807,107,072 MFLOPS: 657.429016 Real_time: 3.608078 Proc_time: 3.042272 Total flpops: 807,024,448 MFLOPS: 265.270355 theoretical flop: 2*512*512*512=268,435,456 Practical flops= 6*512^3 =807,107,072 Using 1 dimensional array float d[size][size]:512 or any size for (int j = 0; j < size; ++j) { for (int k = 0; k < size; ++k) { d[k]=d[k]+e[k]+f[k]+g[k]+r; } } Real_time: 0.002288 Proc_time: 0.002260 Total flpops: 1,048,578 MFLOPS: 464.027161 theroretical flop: *4n^2=4*512^2=1,048,576* practical flop : 4n^2+overhead (other operation?)=1,048,578 3 loop version: Real_time: 1.282257 Proc_time: 1.155990 Total flpops: 536,872,000 MFLOPS: 464.426117 theoretical flop:4n^3 = 536,870,912 practical flop: *4n^3=4*512^3+overheads(other operation?)=536,872,000* thank you

    Read the article

  • Eclipse randomly exits after installation of Blackberry plugin/SDK

    - by canadiancreed
    Hello all Since adding the Blackberry Java classes from their website into eclipse, I've had it where eclipse will randomly close, with no discernible pattern, rhyme, error or reason. Here is the environment/software packages that I am using: Windows XP SP2 Eclipse v3.5.1 Blackberry Java Plugin v1.1.1.200911111641-15 Blackberry Java SDK 4.5.0.21 I've tried the usual steps of complete uninstall and reinstallation of Eclipse and the accompanying plugins on multiple systems with the same configuration, including one that had a fresh install of Windows XP SP2. Upgrading to Eclipse 3.6 didn't work (the plugin wont' install as it's the wrong version), nor the downgrade to 3.4 for the same reason. I also increased the heap size to 512 (system has two gigs of memory) as some research into Eclipse doing this type of thing with Groovy was resolved that way, but again, no dice. Eclipse works great when the blackberry plugins are not installed, and no entries of errors or issues in the event log are helping to show what the issue with these plug-ins might be. So if anyone has ran into this issue, and even better, has a solution, I'd love to hear about it. Thanks in advance. EDIT: An additional to my issue, autoComplete with the Blackberry SDK seems to make this extremely unstable, like almost a guaranteed crash. Is this fixable at all?

    Read the article

  • Understanding floating point problems

    - by Maxim Gershkovich
    Could someone here please help me understand how to determine when floating point limitations will cause errors in your calculations. For example the following code. CalculateTotalTax = function (TaxRate, TaxFreePrice) { return ((parseFloat(TaxFreePrice) / 100) * parseFloat(TaxRate)).toFixed(4); }; I have been unable to input any two values that have caused for me an incorrect result for this method. If I remove the toFixed(4) I can infact see where the calculations start to lose accuracy (somewhere around the 6th decimal place). Having said that though, my understanding of floats is that even small numbers can sometimes fail to be represented or have I misunderstood and can 4 decimal places (for example) always be represented accurately. MSDN explains floats as such... This means they cannot hold an exact representation of any quantity that is not a binary fraction (of the form k / (2 ^ n) where k and n are integers) Now I assume this applies to all floats (inlcuding those used in javascript). Fundamentally my question boils down to this. How can one determine if any specific method will be vulnerable to errors in floating point operations, at what precision will those errors materialize and what inputs will be required to produce those errors? Hopefully what I am asking makes sense.

    Read the article

  • CS Master's Degree Project vs. Thesis options

    - by Nwosh
    I'm doing a master's degree in computer science, and I'm currently at the point where I have to decide between the thesis and non-thesis options offered by my university. The thesis option was my first choice, it entails taking less courses but tends to take more time doing your thesis. The non-thesis option involves taking more coursework, taking a comprehensive exam, and doing a project in one semester with a faculty member. I'd like to pursue a PhD degree eventually (although not right away, I want to get some years of professional experience first), and I heard that having demonstrated the ability to work on a thesis helps a lot with admission (like: not doing thesis raises questions and suggests not being interested in research) and that the experience itself is very good. At the same time, almost everyone I know who did a thesis at my university took a long time (2-3 years), in theory it could be done in 1.5 years. I'm a part time student and I don't really want to spend so much time just getting a master's degree, I could still publish a few papers while working on the project option and I'd be done in a year or so, additionally, I heard having a master's degree with a project and more coursework is more desirable for the industry. So, when applying for a PhD degree in CS at some of the better universities, would the time spent working on the master's thesis help in getting me accepted? Or should I opt for the non-thesis option and hope that the extra coursework and publishing some papers would make up for not working on a thesis?

    Read the article

  • SQL Server 2005 database design - many-to-many relationships with hierarchy

    - by Remnant
    Note I have completely re-written my original post to better explain the issue I am trying to understand. I have tried to generalise the problem as much as possible. Also, my thanks to the original people who responded. Hopefully this post makes things a little clearer. Context In short, I am struggling to understand the best way to design a small scale database to handle (what I perceive to be) multiple many-to-many relationships. Imagine the following scenario for a company organisational structure: Textile Division Marketing Division | | ---------------------- ---------------------- | | | | HR Dept Finance Dept HR Dept Finance Dept | | | | ---------- ---------- ---------- --------- | | | | | | | | Payroll Hiring Audit Tax Payroll Hiring Audit Accounts | | | | | | | | Emps Emps Emps Emps Emps Emps Emps Emps NB: Emps denotes a list of employess that work in that area When I first started with this issue I made four separate tables: Divisions - Textile, Marketing (PK = DivisionID) Departments - HR, Finance (PK = DeptID) Functions - Payroll, Hiring, Audit, Tax, Accounts (PK = FunctionID) Employees - List of all Employees (PK = EmployeeID) The problem as I see it is that there are multiple many-to-many relationships i.e. many departments have many divisions and many functions have many departments. Question Giving the database structure above, suppose I wanted to do the following: Get all employees who work in the Payroll function of the Marketing Division To do this I need to be able to differentiate between the two Payroll departments but I am not sure how this can be done? I understand that I could build a 'Link / Junction' table between Departments and Functions so that I can retrieve which Functions are in which Departments. However, I would still need to differentiate the Division they belong to. Research Effort As you can see I am an abecedarian when it comes to database deisgn. I have spent the last two days resaerching this issue, traversing nested set models, adjacency models, reading that this issue is known not to be NP complete etc. I am sure there is a simple solution?

    Read the article

  • What off-the-shelf licensing system will meet my needs?

    - by Anders Pedersen
    I'm looking for an off-the-shelf license system for desktop software. After some research on the net -- and of course here on StackOverflow -- I haven't found one the suits our needs. I have a couple of must-have features and some would-be-nice features: Must have: Encrypted unlock key Possibility to automate the unlock key generation on my website User info in key so that I can show name and company in an about box and perhaps in reports Nice to have: License managing tools Online activation Nice upgrade possibilities to a version with concurrent license model and subscription model I have looked at Manco, but I find them difficult to work with and the documentation is minimal. Further, I couldn't get the name in the key. Also, the automatic generation of a key on my website has to be done with an application web service, but I would rather program against a DLL. Next I looked at xheo. It is easier to use and the documentation is better, but the price is substantially higher and here you can only get the user name in the license file that you then have to provide together with the unlock key. Could anyone share their experiences on what you are using and how it is working for you?

    Read the article

  • Which CEP product to start with?

    - by Andreas
    Hi, I want to learn more on how to build CEP based applications. So I looked around and found several products (overview found here: http://rulecore.com/CEPblog/?page_id=47). But as there are quite a few at the moment, I don't know which is the best to start with. And overall I just would consider the one available for free. The rest is a bit to expensive for just private use ;) Esper is for free, but without Esper studio it seems quite tedious to develop a cep app. Streambase offers a free trial, but I couldn't find out how long you can use this (if only for a month, no that helpful for longer research). Oracle CEP suite seems quite complete, but in the cep scene - as far as I can see - it is the least recognized compared to Esper or Streambase. So do you have any hints on what is the best way to start with cep development? Is it worth to spent time on working through the oracle documenation or is it better to start with Esper or Streambase? Cheers, Andreas

    Read the article

  • .NET Framework installation requirements

    - by Paja
    What are the requirements for all .NET frameworks and their service packs? This is what I need to know for all available frameworks: .NET Framework prerequisites What other .NET Frameworks does it require? For example: .NET Framework 2.0 does not require anything, .NET Framework 2.0 SP1 requires .NET Framework 2.0 installed, but .NET Framework 3.5 SP1 does not require .NET Framework 3.5 installed (or maybe does? dunno) Reboot requirements Does the installation package require reboot after installation? Clean install requirements Does the installation package require clean install? (No pending delete/rename operations) Administrator privileges Does the installation package require administrator privileges to install? (I guess this is "yes" for all of them...) And I need to know all of this for the following packages: .NET Framework 1.1 .NET Framework 1.1 Language Pack .NET Framework 1.1 SP 1 .NET Framework 2.0 .NET Framework 2.0 Language Pack .NET Framework 2.0 SP 1 .NET Framework 2.0 SP 1 Language Pack .NET Framework 2.0 SP 2 .NET Framework 2.0 SP 2 Language Pack .NET Framework 3.5 .NET Framework 3.5 Language Pack .NET Framework 3.5 SP 1 .NET Framework 3.5 SP 1 Language Pack .NET Framework 4.0 Full .NET Framework 4.0 Client Could you please either tell me all of these requirements, or direct me to the appropriate source? Or maybe both? :-)

    Read the article

< Previous Page | 221 222 223 224 225 226 227 228 229 230 231 232  | Next Page >