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• R plotting multiple histograms on single plot to .pdf as a part of R batch script

  - by Bryce Thomas

  I am writing R scripts which play just a small role in a chain of commands I am executing from a terminal. Basically, I do much of my data manipulation in a Python script and then pipe the output to my R script for plotting. So, from the terminal I execute commands which look something like $python whatever.py | R CMD BATCH do_some_plotting.R. This workflow has been working well for me so far, though I have now reached a point where I want to overlay multiple histograms on the same plot, inspired by this answer to another user's question on Stackoverflow. Inside my R script, my plotting code looks like this: pdf("my_output.pdf") plot(hist(d$original,breaks="FD",prob=TRUE), col=rgb(0,0,1,1/4),xlim=c(0,4000),main="original - This plot is in beta") plot(hist(d$minus_thirty_minutes,breaks="FD",prob=TRUE), col=rgb(1,0,0,1/4),add=T,xlim=c(0,4000),main="minus_thirty_minutes - This plot is in beta") Notably, I am using add=T, which is presumably meant to specify that the second plot should be overlaid on top of the first. When my script has finished, the result I am getting is not two histograms overlaid on top of each other, but rather a 3-page PDF whose 3 individual plots contain the titles: i) Histogram of d$original ii) original - This plot is in beta iii) Histogram of d$minus_thirty_minutes So there's two points here I'm looking to clarify. Firstly, even if the plots weren't overlaid, I would expect just a 2-page PDF, not a 3-page PDF. Can someone explain why I am getting a 3-page PDF? Secondly, is there a correction I can make here somewhere to get just the two histograms plotted, and both of them on the same plot (i.e. 1-page PDF)? The other Stackoverflow question/answer I linked to in the first paragraph did mention that alpha-blending isn't supported on all devices, and so I'm curious whether this has anything to do with it. Either way, it would be good to know if there is a R-based solution to my problem or whether I'm going to have to pipe my data into a different language/plotting engine.

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• Bizzare results when running two Visual Studio Express C++ 2008 solutions

  - by Jamie Keeling

  This is a follow on from my previous question although this is about something else. I've been having a problem where for some reason my message that I pass from one process to another only displays the first letter, in this case "M". My application based on a MSDN sample so to make sure I hadn't missed something I create a seperate solution, added the MSDN sample (Without any changes for my needs) and unsuprisingly it works fine. Now for the weird bit, when I run the MSDN sample running (As in debugging) and have my own application running, the text prints out fine without any problems. The second I run my on it's own without the original MSDN sample being open it fails to work and only shows an "M". I've looked in the debugger and don't seem to notice anything suspicious (It's a slightly dated picture, I've fixed the data type inconsistency). Can anyone provide a solution as to this? I've never encountered anything like this before. To look at my source code it's easier to just look at the link I posted at the top of the question, there's no point in me posting it twice. Thank you for any help.

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• What OpenGL functions are not GPU accelerated?

  - by Xavier Ho

  I was shocked when I read this (from the OpenGL wiki): glTranslate, glRotate, glScale Are these hardware accelerated? No, there are no known GPUs that execute this. The driver computes the matrix on the CPU and uploads it to the GPU. All the other matrix operations are done on the CPU as well : glPushMatrix, glPopMatrix, glLoadIdentity, glFrustum, glOrtho. This is the reason why these functions are considered deprecated in GL 3.0. You should have your own math library, build your own matrix, upload your matrix to the shader. For a very, very long time I thought most of the OpenGL functions use the GPU to do computation. I'm not sure if this is a common misconception, but after a while of thinking, this makes sense. Old OpenGL functions (2.x and older) are really not suitable for real-world applications, due to too many state switches. This makes me realise that, possibly, many OpenGL functions do not use the GPU at all. So, the question is: Which OpenGL function calls don't use the GPU? I believe knowing the answer to the above question would help me become a better programmer with OpenGL. Please do share some of your insights.

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• How can you change the font color of a theme-enabled control?

  - by Edouard Westphal

  Yes, this is again this question: How can I change the font color of a TCheckBox (or any handled control) with Delphi7-Delphi2007 on a themes enabled application? After reading a lot on the internet and on this site, I found 4 kinds of answer: and Most populare (even from QC): You can't, it's designed like that by Microsoft. Create a component that let you draw it like you want. Buy expensive component set that draws like you want. Do not use themes. OK, but I am still unhappy with that. Giving a user colored feedback for the status of a property/data he has on a form, seems legitimate to me. Then I just installed the MSVC# 2008 Express edition, and what a surprise, they can change the color of the font (property ForeColor of the check box) Then what? It does not seem to be a "it's designed like that, by Microsoft." then now the question again: How can I change the font color of a TCheckBox (or any handled control) with Delphi 7 through Delphi 2007 on a theme-enabled application?

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• Why can't I play videos on my Samsung Moment w/Android 2.1 that did play on 1.5?

  - by cpcarroll71

  Hello all. I was directed here by the Google Android Devs Group. I'm still not sure if this is the place I need to be. I've been on forum after forum and asked the same question but no one seems to know the answer or will tell me the REAL correct place to find it. I have a Samsung Moment with Android 2.1. I can not get videos that DID play on Android 1.5 to play on 2.1 now with very few exceptions. I'm not just talking about different videos with the same format, I'm talking about some of the exact same videos that did play in 1.5 will no longer play in 2.1. These are almost all AVI files. If Android doesn't support AVI natively with it's own stock media player then why or how was I able to play these videos flawlessly on 1.5? The way I always played the videos was viewing my SD card, tapping the thumbnail of the video I wanted, and it would automatically open up in the phones media player right away. Now the phone locks up and then eventually gives an error message. Please tell me someone here knows what is going on and if there is a way to fix this. Or if nothing else, tell me where I do need to look to ask this question and find an answer. Thank you.

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• php convert european datetime to mysql datetime

  - by Mathlight

  I'm really stuck with this problem. I've got an datetime string like this: 28-06-14 11:01:00 I'm trying to convert it to 2014-06-28 11:01:00 so that i can insert it into the database ( with field type datetime. I've tryed multiple things like this: $datumHolder = new DateTime($data['datum'], new DateTimeZone('Europe/Amsterdam')); $datum1 = $datumHolder -> format("Y-m-d H:i:s"); $datum2 = date( 'Y-m-d', strtotime(str_replace('-', '/', $data['datum']) ) ); $datum3 = DateTime::createFromFormat( 'Y-m-d-:Hi:s', $data['datum']); This is the output i get: datum1: 2028-06-14 11:01:00 datum2: 1970-01-01 And i get an error for datum3: echo "datum3: " . $datum3->format( 'Y-m-d H:i:s'); . '<br />'; Call to a member function format() on a non-object So my question is very clear... What am I doing wrong / how to get this working? Thanks in advantage guys! I know that this question is asked many, many times... But whatever i try, i can't get it working...

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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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• Does the managed main UI thread stay on the same (unmanaged) Operation System thread?

  - by Daniel Rose

  I am creating a managed WPF UI front-end to a legacy Win32-application. The WPF front-end is the executable; as part of its startup routines I start the legacy app as a DLL in a second thread. Any UI-operation (including CreateWindowsEx, etc.) by the legacy app is invoked back on the main UI-thread. As part of the shutdown process of the app I want to clean up properly. Among other things, I want to call DestroyWindow on all unmanaged windows, so they can properly clean themselves up. Thus, during shutdown I use EnumWindows to try to find all my unmanaged windows. Then I call DestroyWindow one the list I generate. These run on the main UI-thread. After this background knowledge, on to my actual question: In the enumeration procedure of EnumWindows, I have to check if one of the returned top-level windows is one of my unmanaged windows. I do this by calling GetWindowThreadProcessId to get the process id and thread id of the window's creator. I can compare the process id with Process.GetCurrentProcess().Id to check if my app created it. For additional security, I also want to see if my main UI-thread created the window. However, the returned thread id is the OS's ThreadId (which is different than the managed thread id). As explained in this question, the CLR reserves the right to re-schedule the managed thread to different OS threads. Can I rely on the CLR to be "smart enough" to never do this for the main UI thread (due to thread-affinity of the UI)? Then I could call GetCurrentThreadId to get the main UI-thread's unmanaged thread id for comparison.

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• Zend Framework :: Is this code good for user login (Its begining- because that I want to know if its

  - by Yosef

  Hi, I new in Zend. Main Question: Is this code good for user login (Its beginning- because that I want to know if its can be improve)? Code understanding question: Is every time that in action call to his view- code execution in action not going to next row until view request? (I asking about IndexAction that I write down) Thanks view index.phtml <? echo $this->form controller IndexAction.php public function indexAction() { $form=new Application_Form_Login(); $this->view->form = $form; if ($this->getRequest()->isPost()) { $formData = $this->getRequest()->getPost(); if ($form->isValid($formData)) { echo " test value username: ".$form->getValue('username'); } } } form Login.php public function init() { $this->setMethod('post'); $this->setName('user login'); $username = new Zend_Form_Element_Text('username'); $username->setLabel("username") ->setRequired(true) ->addFilter('StripTags') ->addFilter('StringTrim') ->addValidator('NotEmpty'); $password = new Zend_Form_Element_Password('password'); $password->setLabel('password') ->setRequired(true) ->addFilter('StripTags') ->addFilter('StringTrim') ->addValidator('NotEmpty'); $submit = new Zend_Form_Element_Submit('submit'); $this->addElements(array($username, $password, $submit)); }

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• How do C++ compilers actually pass reference parameters?

  - by T.E.D.

  This question came about as a result of some mixed-langauge programming. I had a Fortran routine I wanted to call from C++ code. Fortran passes all its parameters by reference (unless you tell it otherwise). So I thought I'd be clever (bad start right there) in my C++ code and define the Fortran routine something like this: extern "C" void FORTRAN_ROUTINE (unsigned & flag); This code worked for a while but (of course right when I needed to leave) suddenly started blowing up on a return call. Clear indication of a munged call stack. Another engineer came behind me and fixed the problem, declaring that the routine had to be deinfed in C++ as extern "C" void FORTRAN_ROUTINE (unsigned * flag); I'd accept that except for two things. One is that it seems rather counter-intuitive for the compiler to not pass reference parameters by reference, and I can find no documentation anywhere that says that. The other is that he changed a whole raft of other code in there at the same time, so it theoretically could have been another change that fixed whatever the issue was. So the question is, how does C++ actually pass reference parameters? Is it perhaps free to do copy-in, copy-out for small values or something? In other words, are reference parameters utterly useless in mixed-language programming? I'd like to know so I don't make this same code-killing mistake ever again.

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• (illustrator scripting) how to release objects to layers(sequence) but retain object's name?

  - by Eugene

  Hi, I've asked the same question to adobe scripting forum. but seems there are not many forum users there, and I'm asking the same question here. I was writing my first illustrator script to export all layers to png files with layer structure converted to file structure. I found there are many layers that my script can't detect and found out that they are not actually layers but objects(or groups). Found a layer menu (release to layers), but doesn't quite solve the problem perfectly. initially I have this layer 001 object 01 object 1 object 2 release to layers(sequence) on object 01 gives layer 001 layer 91(whatever the layer number illustrator gives when release to layers are performed) layer 92 object 1 layer 93 object 2 now I need to convert them to (so that layer can retain the name of the object) layer 001 layer 01 layer 1 object 1 layer 2 object 2 I have hundreds of layer 001, and couple thousands of object 01, and wonder if anything can be done with script to do this... If it's possible to detect object in a script, I could rewrite the 'release to layers' functionality in script maybe. Any help would be greatly appreciated.

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• Unable to save data in database manually and get latest auto increment id, cakePHP

  - by shabby

  I have checked this question as well and this one as well. I am trying to implement the model described in this question. What I want to do is, on the add function of message controller, create a record in thread table(this table only has 1 field which is primary key and auto increment), then take its id and insert it in the message table along with the user id which i already have, and then save it in message_read_state and thread_participant table. This is what I am trying to do in Thread Model: function saveThreadAndGetId(){ //$data= array('Thread' => array()); $data= array('id' => ' '); //Debugger::dump(print_r($data)); $this->save($data); debug('id: '.$this->id); $threadId = $this->getInsertID(); debug($threadId); $threadId = $this->getLastInsertId(); debug($threadId); die(); return $threadId; } $data= array('id' => ' '); This line from the above function adds a row in the thread table, but i am unable to retrieve the id. Is there any way I can get the id, or am I saving it wrongly? Initially I was doing the query thing in the message controller: $this->Thread->query('INSERT INTO threads VALUES();'); but then i found out that lastId function doesnt work on manual queries so i reverted.

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• How to get the set of beans that are to be created in Spring?

  - by cyborg

  So here's the scenario: I have a Spring XML configuration with some lazy-beans, some not lazy-beans and some beans that depend on other beans. Eventually Spring will resolve all this so that only the beans that are meant to be created are created. The question: how can I programmatically tell what this set is? When I use context.getBean(name) that initializes the bean. BeanDefinition.isLazyInit() will only tell me how I defined the bean. Any other ideas? ETA: In DefaultListableBeanFactory: public void preInstantiateSingletons() throws BeansException { if (this.logger.isInfoEnabled()) { this.logger.info("Pre-instantiating singletons in " + this); } synchronized (this.beanDefinitionMap) { for (Iterator it = this.beanDefinitionNames.iterator(); it.hasNext();) { String beanName = (String) it.next(); RootBeanDefinition bd = getMergedLocalBeanDefinition(beanName); if (!bd.isAbstract() && bd.isSingleton() && !bd.isLazyInit()) { if (isFactoryBean(beanName)) { FactoryBean factory = (FactoryBean) getBean(FACTORY_BEAN_PREFIX + beanName); if (factory instanceof SmartFactoryBean && ((SmartFactoryBean) factory).isEagerInit()) { getBean(beanName); } } else { getBean(beanName); } } } } } The set of instantiable beans is initialized. When initializing this set any beans not in this set referenced by this set will also be created. From looking through the source it does not look like there's going to be any easy way to answer my question.

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• Should a programmer have mastery over C++

  - by Yogendra

  I was wondering if it is necessary for programmers to have expertise on at least 1 programming language? Programming languages like C#, java, VB.Net etc change every year or two. Should a programmer have mastery over C++, which is a stable language and rarely undergoes changes? I am a C# developer and using it for about 7 years now, I still don't have mastery on it. EDIT I think my question is being misunderstood. I am not against changes or evolution. I love the new features and abstraction provided by languages such as C#, VB, Java. And I keep waiting for new features if it makes a programmers life easy. But this fact also make this languages very difficult to master. They are continuously evolving. Languages like C++ have slow evolution cycle. So given this scenario, Is it helpful to be master of C++? This is what my original question meant. Note:- Based on the answers by friends below, I have understood that languages and framework are tools for expressing the concepts. Also it might be a good idea to express the concepts in different programming languages.

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• Vim: change formatting of variables in a script

  - by sixtyfootersdude

  I am using vim to edit a shell script (did not use the right coding standard). I need to change all of my variables from camel-hum-notation startTime to caps-and-underscore-notation START_TIME. I do not want to change the way method names are represented. I was thinking one way to do this would be to write a function and map it to a key. The function could do something like generating this on the command line: s/<word under cursor>/<leave cursor here to type what to replace with> I think that this function could be applyable to other situations which would be handy. Two questions: Question 1: How would I go about creating that function. I have created functions in vim before the biggest thing I am clueless about is how to capture movement. Ie if you press dw in vim it will delete the rest of a word. How do you capture that? Also can you leave an uncompleted command on the vim command line? Question 2: Got a better solution for me? How would you approach this task?

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• Viewing recently edited etherpads (note new 'etherpad' tag for open sourced etherpad code!)

  - by dreeves

  Prescript: The amazing etherpad was recently open sourced. Get it here: http://code.google.com/p/etherpad. This is the first question that I know of on StackOverflow about the etherpad code. If you're part of the etherpad open source community, you might want to subscribe to the RSS feed for questions tagged 'etherpad' just in case this catches on! My actual question, which assumes you have etherpad installed on your own server: First, here's a query to view recently edited pads: SELECT id,lastWriteTime,creationTime,headRev FROM PAD_SQLMETA ORDER BY lastWriteTime, headRev; Or, if you want to run it from a unix prompt: mysql -u root -pPASSWD etherpad -e "select id,lastWriteTime,creationTime,headRev from PAD_SQLMETA order by lastWriteTime, headRev" That's handy, however lastWriteTime actually gets updated every time someone so much as views a pad in their browser. I'd rather sort the pads by when they were actually last edited. There's probably a fancy SQL query involving a join with another table that would show actual last edit time. Does anyone know what that is? Alternatively, you could have a script that notices when headRev changes but that doesn't seem like the cleanest way to do it.

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• Freelance web hosting - what are good LAMP choices?

  - by tkotitan

  I think it's best if I ask this question with an example scenario. Let's say your mom-and-pop local hardware store has never had a website, and they want you, the freelance developer to build them a website. You have all the skills to run a LAMP setup and admin a system, so the difficult question you ask yourself is - where will I host it? As you aren't going to host it out of the machine in your apartment. Let's say you want to be able to customize your own system, install the version of PHP you want, and manage your own database. Perhaps the best kind of hosting is to get a virtual machine so you can customize the system as you see fit. But this essentially a "set it and forget it" site you make, bill by the hour for, and then are done. In other words, the hosting should not be an issue. Given the requirements of hosting a website: Unlimited growth potential needing good amounts of bandwidth to handle visitors Wide range of system and programming options allowing it to be portable Relatively cheap (not necessarily the cheapest) or reasonable scaling cost Reliable hosting with good support Hosted entirely on the host company's hardware Who would you pick to host this website? Yes I am asking for a business/company recommendation. Is there a clear answer for this scenario, or a good source that can reliably give the current answer? I know there are all kinds of schemes out there. I'm just wondering if any one company fills the bill for freelancers and stands out in such a crowded market.

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• how to handle empty selection in a jface bound combobox?

  - by guido

  I am developing a search dialog in my eclipse-rcp application. In the search dialog I have a combobox as follows: comboImp = new CCombo(grpColSpet, SWT.BORDER | SWT.READ_ONLY); comboImp.setBounds(556, 46, 184, 27); comboImpViewer = new ComboViewer(comboImp); comboImpViewer.setContentProvider(new ArrayContentProvider()); comboImpViewer.setInput(ImpContentProvider.getInstance().getImps()); comboImpViewer.setLabelProvider(new LabelProvider() { @Override public String getText(Object element) { return ((Imp)element).getImpName(); } }); Imp is a database entity, ManyToOne to the main entity which is searched, and ImpContentProvider is the model class which speaks to embedded sqlite database via jpa/hibernate. This combobox is supposed to contain all instances of Imp, but to also let empty selection; it's value is bound to a service bean as follows: IObservableValue comboImpSelectionObserveWidget = ViewersObservables.observeSingleSelection(comboImpViewer); IObservableValue filterByImpObserveValue = BeansObservables.observeValue(searchPrep, "imp"); bindingContext.bindValue(comboImpSelectionObserveWidget, filterByImpObserveValue , null, null); As soon as the user clicks on the combo, a selection (first element) is made: I can see the call to a selectionlistener i added on the viewer. My question is: after a selection has been made, how do I let the user change his mind and have an empty selection in the combobox? should I add a "fake" empty instance of Imp to the List returned by the ImpContentProvider? or should I implement an alternative to ArrayContentProvider? and one additional related question is: why calling deselectAll() and clearSelection() on the combo does NOT set a null value to the bound bean?

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• Java Enumeration of Musical Notes

  - by Crupler

  How would you create an enumeration of the musical notes in Java, with each notes having an octave and then a keyed variable? This is what I have so far... public enum Notes { c, cS, d, dS, e, f, fS, g, gS, a, aS, b; int octave; boolean isPlaying; } So when I access the enums in my code I write something like this... Notes.c.octave = 4; Notes.c.isPlaying = true; Now here is my question: How can I have an isPlaying boolean for each note in each octave? Like so: Notes.c.octave.isPlaying = true; Or would I have to go like: public enum Notes { c1, cS1, d1, dS1, e1, f1, fS1, g1, gS1, a1, aS1, b1 c2, cS2, d2, dS2, e2, f2, fS2, g2, gS2, a2, aS2, b2; etc... boolean isPlaying; } Thank you in advance for taking your time to answer this question!

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• LINQ extention SelectMany in 3.5 vs 4.0?

  - by Moberg

  Hi When I saw Darins suggestion here .. IEnumerable<Process> processes = new[] { "process1", "process2" } .SelectMany(Process.GetProcessesByName); ( http://stackoverflow.com/questions/3059667/process-getprocessesbyname/3059733#3059733 ) .. I was a bit intrigued and I tried it in VS2008 with .NET 3.5 - and it did not compiling unless I changed it to .. IEnumerable<Process> res = new string[] { "notepad", "firefox", "outlook" } .SelectMany(s => Process.GetProcessesByName(s)); Having read some Darins answers before I suspected that it was me that were the problem, and when I later got my hands on a VS2010 with.NET 4.0 - as expected - the original suggestion worked beautifully. My question is : What have happend from 3.5 to 4.0 that makes this (new syntax) possible? Is it the extentionmethods that have been extended(hmm) or new rules for lambda syntax or? I've tried to search but my google-fu was not strong enough. Please forgive if the question is a bit naive and note that I've taged it as beginner :)

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• Java string to double conversion.

  - by wretrOvian

  Hi, I've been reading up on the net about the issues with handling float and double types in java. Unfortunately, the image is still not clear. Hence, i'm asking here direct. :( My MySQL table has various DECIMAL(m,d) columns. The m may range from 5 to 30. d stays a constant at 2. Question 1. What equivalent data-type should i be using in Java to work (i.e store, retrieve, and process) with the size of the values in my table? (I've settled with double - hence this post). Question 2. While trying to parse a double from a string, i'm getting errors Double dpu = new Double(dpuField.getText()); for example - "1" -> java.lang.NumberFormatException: empty String "10" -> 1.0 "101" -> 10.0 "101." -> 101.0 "101.1" -> 101.0 "101.19" -> 101.1 What am i doing wrong? What is the correct way to convert a string to a double value? And what measures should i take to perform operations on such values?

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• Span with white-space style in IE (7) applied _past_ end of span

  - by WaldenL

  We've got an application where users can enter "notes" into a rich edit control (Telerik's RedEditor, but that doesn't matter here). We had a user enter notes from w/in Safari that had a <span></span> in the middle of the note, and that span had a style on it specifying white-space:pre The HTML of the note was in the form of: <div> This is a note <span class="Apple-tab-span" style="white-space: pre; "> </span> and here's more of the note. </div> Simple enough, the style should apply to the span, and the span had 4 spaces in it. There should have been 4 spaces in the resulting output. Here's the problem. IE seems to apply that white-space: pre; style not only to the span, but to the enclosing div! Therefore, this long line that should have wrapped since it's not in the span, now pushed the document out until the line fits on the page. What am I missing. I know IE has problems, but this doesn't seem right, even for IE. So, the question(s): 1) Am I correct that the white-space attribute should only have applied to the span? 2) Can this be resolved somehow? Remember, I'm not in control of the content being entered. And it's entered from a mac w/Safari and being viewed in IE. Edit: The doctype on the page in question is: <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

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• JPA - Real primary key generated ID for references

  - by Val

  I have ~10 classes, each of them, have composite key, consist of 2-4 values. 1 of the classes is a main one (let's call it "Center") and related to other as one-to-one or one-to-many. Thinking about correct way of describing this in JPA I think I need to describe all the primary keys using @Embedded / @PrimaryKey annotations. Question #1: My concern is - does it mean that on the database level I will have # of additional columns in each table referring to the "Center" equal to number of column in "Center" PK? If yes, is it possible to avoid it by using some artificial unique key for references? Could you please give an idea how real PK and the artificial one needs to be described in this case? Note: The reason why I would like to keep the real PK and not just use the unique id as PK is - my application have some data loading functionality from external data sources and sometimes they may return records which I already have in local database. If unique ID will be used as PK - for new records I won't be able to do data update, since the unique ID will not be available for just downloaded ones. At the same time it is normal case scenario for application and it just need to update of insert new records depends on if the real composite primary key matches. Question #2: All of the 10 classes have common field "date" which I described in an abstract class which each of them extends. The "date" itself is never a key, but it always a part of composite key for each class. Composite key is different for each class. To be able to use this field as a part of PK should I describe it in each class or is there any way to use it as is? I experimented with @Embedded and @PrimaryKey annotations and always got an error that eclipselink can't find field described in an abstract class. Thank you in advance! PS. I'm using latest version of eclipselink & H2 database.

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• 3D and AI basics. The foundation before the coding.

  - by Allan

  Hi, everyone. (If you have the time and patience:) I've recently made the decision to study programming seriously and I'm about to order TAOCP and Concrete Mathematics to begin my studies (please don't get caught up on this). I'm very much interested in learning and understanding how 3D works but I'm aware that if I plan to do it right there's still a long walk before I get to actually play with 3D coding. Now to the question.. (tl;dr) Excluding programming itself, what disciplines do I have to be familiar with to code 3D? What kinds of mathematics? Physics? What else? What books do you recommend on such subjects? Now read it all again but replacing "3D" with "AI". Please don't recommend computer-specific books. The question is about the foundation to be learned before using the machine. Also, if possible, please keep the list brief; I plan to order one book on each subject but no more than that for now. Excuse me for any English mistakes, it's not my first language. Thank you.

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• How do I get Facebook Application Login to work

  - by Javaaaa

  I just started making an application for Facebook, however I ran into problem early on. The first step I want people to do is to give permission to access their profile. All over the web are examples of how to do this with: $user_id = $facebook->require_login(); However, this is the way it works using the Old PHP API. I have downloaded and installed the new one in my application folder and it is not working anymore. My question is (and i really have been searching for an answer for a long time) what is the code to do this with the new API? (and related question: is it better to use the old API, or learn to work with the new one when I am just starting making apps right now) I have this code now; <?php // Awesome Facebook Application // // Name: - // require_once 'facebook-php-sdk/src/facebook.php'; // Create our Application instance. $facebook = new Facebook(array( 'appId' => $app_id, 'secret' => $app_secret, 'cookie' => true )); $loginUrl = $facebook->getLoginUrl(array( 'req_perms' => 'email,user_birthday,publish_stream,sms,status_update,user_location' )); echo "<p>hello, <fb:name uid=\"$user_id\" useyou=\"false\" />!</p>"; ?>

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