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  • Hibernate: Dirty Checking and Only Update of Dirty Attributes?

    - by jens
    Hello Experts, in "good old JDBC days" I wrote a lot of SQL Queries that did very targeted updates of only the "attributes/members" that were actually changed: For Example having an object with the following members: public String name; public String address; public Date date; If only date was changed in some Business Method I would only issue an SQL UPDATE for the date member. ==It seems however (thats my "impression" of hibernate) that when working with a standard Hibernate mapping (mapping the full class), even updates of only one single member lead to a full update of the object in SQL Statements generated by Hibernate. My Questions are: 1.) Is this observation correct, that hibernate DOES NOT intelligently check (in a fully mapped class), what member(s) where changed and then only issue updates for the specific changed members, but rather always will update (in the generated SQL Update Statement) all mapped members (of a class), even if they were not changed (in case the object is dirty due to one member being dirty...) 2.) What can I do to make Hibernate only update those members, that have been changed? I am searching for a solution to have hibernate only update the member that actually changed. (I know hibernate does some big work on doing dirty-checking, but as far as I know this dirtychecking is only relevant to identify if the object as whole is dirty, not what single member is dirty.) Thank you very much! Jens

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  • Convert scientific notation to decimal notation

    - by Ankur
    There is a similar question on SO which suggests using NumberFormat which is what I have done. I am using the parse() method of NumberFormat. public static void main(String[] args) throws ParseException{ DecToTime dtt = new DecToTime(); dtt.decToTime("1.930000000000E+02"); } public void decToTime(String angle) throws ParseException{ DecimalFormat dform = new DecimalFormat(); //ParsePosition pp = new ParsePosition(13); Number angleAsNumber = dform.parse(angle); System.out.println(angleAsNumber); } The result I get is 1.93 I didn't really expect this to work because 1.930000000000E+02 is a pretty unusual looking number, do I have to do some string parsing first to remove the zeros? Or is there a quick and elegant way?

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  • make RMI Stub with netBeans

    - by park
    I see some where in the web that we can make Stub dynamically with Netbeans and it`s a good feature of it. I search a lot but all hits are from Old version (4 or 5) and others told a complete reference is in Netbeans website but the links is removed and i couldn`t find it in the site. Broken Link : rmi.netbeans.org Please if there is way which i don`t know tell me or there is not let me know for not search any more and try to work with rmic. more search results : http://forums.sun.com/thread.jspa?threadID=5037503 http://forums.netbeans.org/post-8076.html&highlight= Thanks

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  • How do I send an email with embedded images AND regular attachments in JavaMail?

    - by Chris
    Hi, I'd like to know how to build an SMTP multipart message in the correct order so that it will render correctly on the iPhone mail client (rendering correctly in GMail). I'm using Javamail to build up an email containing the following parts: A body part with content type "text/html; UTF-8" An embedded image attachment. A file attachment I am sending the mail via GMail SMTP (via SSL) and the mail is sent and rendered correctly using a GMail account, however, the mail does not render correctly on the iPhone mail client. On the iPhone mail client, the image is rendered before the "Before Image" text when it should be rendered afterwards. After the "Before Image" text there is an icon with a question mark (I assume it means it couldn't find the referenced CID). I'm not sure if this is a limitation of the iPhone mail client or a bug in my mail sending code (I strongly assume the latter). I think that perhaps the headers on my parts might by incorrect or perhaps I am providing the multiparts in the wrong order. I include the text of the received mail as output by gmail (which renders the file correc Message-ID: <[email protected]> Subject: =?UTF-8?Q?Test_from_=E3=82=AF=E3=83=AA=E3=82=B9?= MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_0_20870565.1274154021755" ------=_Part_0_20870565.1274154021755 Content-Type: application/octet-stream Content-Transfer-Encoding: base64 Content-ID: <20100518124021763_368238_0> iVBORw0K ----- TRIMMED FOR CONCISENESS 6p1VVy4alAAAAABJRU5ErkJggg== ------=_Part_0_20870565.1274154021755 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: 7bit <html><head><title>Employees Favourite Foods</title> <style> body { font: normal 8pt arial; } th { font: bold 8pt arial; white-space: nowrap; } td { font: normal 8pt arial; white-space: nowrap; } </style></head><body> Before Image<br><img src="cid:20100518124021763_368238_0"> After Image<br><table border="0"> <tr> <th colspan="4">Employees Favourite Foods</th> </tr> <tr> <th align="left">Name</th><th align="left">Age</th><th align="left">Tel.No</th><th align="left">Fav.Food</th> </tr> <tr style="background-color:#e0e0e0"> <td>Chris</td><td>34</td><td>555-123-4567</td><td>Pancakes</td> </tr> </table></body></html> ------=_Part_0_20870565.1274154021755 Content-Type: text/plain; charset=us-ascii; name=textfile.txt Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=textfile.txt This is a textfile with numbers counting from one to ten beneath this line: one two three four five six seven eight nine ten(no trailing carriage return) ------=_Part_0_20870565.1274154021755-- Even if you can't assist me with this, I would appreciate it if any members of the forum could forward me a (non-personal) mail that includes inline images (not external hyperlinked images though). I just need to find a working sample then I can move past this. Thanks, Chris.

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  • best way to pick a random subset from a collection?

    - by Tom
    I have a set of objects in a Vector from which I'd like to select a random subset (e.g. 100 items coming back; pick 5 randomly). In my first (very hasty) pass I did an extremely simple and perhaps overly clever solution: Vector itemsVector = getItems(); Collections.shuffle(itemsVector); itemsVector.setSize(5); While this has the advantage of being nice and simple, I suspect it's not going to scale very well, i.e. Collections.shuffle() must be O(n) at least. My less clever alternative is Vector itemsVector = getItems(); Random rand = new Random(System.currentTimeMillis()); // would make this static to the class List subsetList = new ArrayList(5); for (int i = 0; i < 5; i++) { // be sure to use Vector.remove() or you may get the same item twice subsetList.add(itemsVector.remove(rand.nextInt(itemsVector.size()))); } Any suggestions on better ways to draw out a random subset from a Collection?

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  • Socket server with multiple clients, sending messages to many clients without hurting liveliness

    - by Karl Johanson
    I have a small socket server, and I need to distribute various messages from client-to-client depending on different conditionals. However I think I have a small problem with livelyness in my current code, and is there anything wrong in my approach: public class CuClient extends Thread { Socket socket = null; ObjectOutputStream out; ObjectInputStream in; CuGroup group; public CuClient(Socket s, CuGroup g) { this.socket = s; this.group = g; out = new ObjectOutputStream(this.socket.getOutputStream()); out.flush(); in = new ObjectInputStream(this.socket.getInputStream()); } @Override public void run() { String cmd = ""; try { while (!cmd.equals("client shutdown")) { cmd = (String) in.readObject(); this.group.broadcastToGroup(this, cmd); } out.close(); in.close(); socket.close(); } catch (Exception e) { System.out.println(this.getName()); e.printStackTrace(); } } public void sendToClient(String msg) { try { this.out.writeObject(msg); this.out.flush(); } catch (IOException ex) { } } And my CuGroup: public class CuGroup { private Vector<CuClient> clients = new Vector<CuClient>(); public void addClient(CuClient c) { this.clients.add(c); } void broadcastToGroup(CuClient clientName, String cmd) { Iterator it = this.clients.iterator(); while (it.hasNext()) { CuClient cu = (CuClient)it.next(); cu.sendToClient(cmd); } } } And my main-class: public class SmallServer { public static final Vector<CuClient> clients = new Vector<CuClient>(10); public static boolean serverRunning = true; private ServerSocket serverSocket; private CuGroup group = new CuGroup(); public void body() { try { this.serverSocket = new ServerSocket(1337, 20); System.out.println("Waiting for clients\n"); do { Socket s = this.serverSocket.accept(); CuClient t = new CuClient(s,group); System.out.println("SERVER: " + s.getInetAddress() + " is connected!\n"); t.start(); } while (this.serverRunning); } catch (IOException ex) { ex.printStackTrace(); } } public static void main(String[] args) { System.out.println("Server"); SmallServer server = new SmallServer(); server.body(); } } Consider the example with many more groups, maybe a Collection of groups. If they all synchronize on a single Object, I don't think my server will be very fast. I there a pattern or something that can help my liveliness?

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  • Why does appending "" to a String save memory?

    - by hsmit
    I used a variable with a lot of data in it, say String data. I wanted to use a small part of this string in the following way: this.smallpart = data.substring(12,18); After some hours of debugging (with a memory visualizer) I found out that the objects field smallpart remembered all the data from data, although it only contained the substring. When I changed the code into: this.smallpart = data.substring(12,18)+""; ..the problem was solved! Now my application uses very little memory now! How is that possible? Can anyone explain this? I think this.smallpart kept referencing towards data, but why? UPDATE: How can I clear the big String then? Will data = new String(data.substring(0,100)) do the thing?

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  • Creating GUI for Bantumi game

    - by owca
    I've written backend for simple Bantumi game. Now I'd like to create a simple GUI for it, so that it would look like this : How to start ? What layout should I use, and what type of component each element should be? Classes : Basket Player Game Main Shared

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  • Paging of images in blackberry

    - by Maneesh
    How to display images in the form of pages where only one page is displayed at a time on blackberry screen. On scrolling down subsequent images will load at run time. So that loading of images do not consume time at startup.

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  • Better to build or buy a compute grid platform?

    - by James B
    I am looking to do some quite processor-intensive brute force processing for string matching. I have run my prototype in a multi-threaded environment and compared the performance to an implementation using Gridgain with a couple of nodes (also multithreaded). The performance I observed was that my Gridgain implementation performed slower to my multithreaded implementation. It could be the case that there was a flaw in my gridgain implementation, but it was only a prototype, and I thought the results were indicative. So my question is this: What are the advantages of having to learn and then build an implementation for a particular grid platform (hadoop, gridgain, or EC2 if going hosted - other suggestions welcome), when one could fairly easily put together a lightweight compute grid platform with a much shallower learning curve?...i.e. what do we get for free with these cloud/grid platforms that are worth having/tricky to implement? (Please note, I don't have any need for a data grid) Cheers, -James (p.s. Happy to make this community wiki if needbe)

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  • hibernate column uniqueness question

    - by Seth
    I'm still in the process of learning hibernate/hql and I have a question that's half best practices question/half sanity check. Let's say I have a class A: @Entity public class A { @Id @GeneratedValue(strategy=GenerationType.AUTO) private Long id; @Column(unique=true) private String name = ""; //getters, setters, etc. omitted for brevity } I want to enforce that every instance of A that gets saved has a unique name (hence the @Column annotation), but I also want to be able to handle the case where there's already an A instance saved that has that name. I see two ways of doing this: 1) I can catch the org.hibernate.exception.ConstraintViolationException that could be thrown during the session.saveOrUpdate() call and try to handle it. 2) I can query for existing instances of A that already have that name in the DAO before calling session.saveOrUpdate(). Right now I'm leaning towards approach 2, because in approach 1 I don't know how to programmatically figure out which constraint was violated (there are a couple of other unique members in A). Right now my DAO.save() code looks roughly like this: public void save(A a) throws DataAccessException, NonUniqueNameException { Session session = sessionFactory.getCurrentSession(); try { session.beginTransaction(); Query query = null; //if id isn't null, make sure we don't count this object as a duplicate if(obj.getId() == null) { query = session.createQuery("select count(a) from A a where a.name = :name").setParameter("name", obj.getName()); } else { query = session.createQuery("select count(a) from A a where a.name = :name " + "and a.id != :id").setParameter("name", obj.getName()).setParameter("name", obj.getName()); } Long numNameDuplicates = (Long)query.uniqueResult(); if(numNameDuplicates > 0) throw new NonUniqueNameException(); session.saveOrUpdate(a); session.getTransaction().commit(); } catch(RuntimeException e) { session.getTransaction().rollback(); throw new DataAccessException(e); //my own class } } Am I going about this in the right way? Can hibernate tell me programmatically (i.e. not as an error string) which value is violating the uniqueness constraint? By separating the query from the commit, am I inviting thread-safety errors, or am I safe? How is this usually done? Thanks!

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  • Writing a Servlet that checks to see if JSP's exist and forwards to another JSP if they aren't

    - by Omar Kooheji
    I've beeb tasked with writing a servlet that intercepts a call to and JSP in a specific directoy, check that the file exists and if it does just forwarding to that file, if if doesn't I'm to forward to a default JSP. I've setup the web.xml as follows: <servlet> <description>This is the description of my J2EE component</description> <display-name>This is the display name of my J2EE component</display-name> <servlet-name>CustomJSPListener</servlet-name> <servlet-class> ... CustomJSPListener</servlet-class> <load-on-startup>1</load-on-startup> </servlet> ... <servlet-mapping> <servlet-name>CustomJSPListener</servlet-name> <url-pattern>/custom/*</url-pattern> </servlet-mapping> And the doGet method of the servlet is as follows: public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { logger.debug(String.format("Intercepted a request for an item in the custom directory [%s]",request.getRequestURL().toString())); String requestUri = request.getRequestURI(); // Check that the file name contains a text string if (requestUri.toLowerCase(Locale.UK).contains("someText")){ logger.debug(String.format("We are interested in this file [%s]",requestUri)); File file = new File(requestUri); boolean fileExists = file.exists(); logger.debug(String.format("Checking to see if file [%s] exists [%s].",requestUri,fileExists)); // if the file exists just forward it to the file if (fileExists){ getServletConfig().getServletContext().getRequestDispatcher( requestUri).forward(request,response); } else { // Otherwise redirect to default.jsp getServletConfig().getServletContext().getRequestDispatcher( "/custom/default.jsp").forward(request,response); } } else { // We aren't responsible for checking this file exists just pass it on to the requeseted jsp getServletConfig().getServletContext().getRequestDispatcher( requestUri).forward(request,response); } } This seems to result in an error 500 from tomcat, I think this is because the servlet is redirecting to the same folder which is then being intercepted again by the servlet, resulting in an infinite loop. Is there a better way to do this? I'm lead to believe that I could use filters to do this, but I don't know very much about them.

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  • Trouble getting started with Spring Roo and GWT

    - by Abdel Olakara
    Hi all, I am trying to get started with SpringRoo and GWT after seeing the keynote.. unfortunately I am stuck at this issue. I successfully created the project using Roo and added the persistence, the entities and when I perform the command "perform package" I get this error: 23/5/10 12:10:13 AM AST: [ERROR] ApplicationEntityTypesProcessor cannot be resolved 23/5/10 12:10:13 AM AST: [ERROR] ApplicationEntityTypesProcessor cannot be resolved to a type 23/5/10 12:10:13 AM AST: [WARN] advice defined in org.springframework.mock.staticmock.AnnotationDrivenStaticEntityMockingControl has not been applied [Xlint:adviceDidNotMatch] 23/5/10 12:10:13 AM AST: [WARN] advice defined in org.springframework.mock.staticmock.AbstractMethodMockingControl has not been applied [Xlint:adviceDidNotMatch] 23/5/10 12:10:13 AM AST: Build errors for helloroo; org.apache.maven.lifecycle.LifecycleExecutionException: Failed to execute goal org.codehaus.mojo:aspectj-maven-plugin:1.0:compile (default) on project helloroo: Compiler errors : error at import tp.gwt.request.ApplicationEntityTypesProcessor; I see this in the Maven console and cannot complete the build..I know there is some jar missing but how and why? because I downloaded all the latest version including GWT milestone release. Any idea why this error is occurring? How do I resolve this issue? Thanks in Advance, Abdel Olakara

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  • Problem of instanceOf

    - by eric2323223
    Hi, could anyone tell me why this code won't compile? public boolean isOf(Class clazz, Object obj){ if(obj instanceof clazz){ return true; }else{ return false; } } Why I can't pass a class variable to instanceOf? Thanks in advance.

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  • How can I load file into web app through certain periods?

    - by Elena
    Hi all! I have next task: I need to load the same file into my web app several times, for example - twice a day! Suppose in that file I have information, that changes, and I need to load this info into my app to change the statistics for example. How can I load file several times (twice an hour, or twice a day)? What should I use? Is any algorithm to do that? I am not allowed to use external libraries like Quartz Scheduler. So I need to do it with Thread and/or Timer. Can anybody give me some example or algorithm how to do it. Where can I create the entry point to my Thread, can I do it in managed bean or I need some sort of filter/listener/servlet. I works with jsf and richFaces. Maybe in this technologies there are some algorithms to solve my problem. Any ideas? Thanks very much for help!

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  • Turning off hibernate logging console output

    - by Jared
    I'm using hibernate 3 and want to stop it from dumping all the startup messages to the console. I tried commenting out the stdout lines in log4j.properties but no luck. I've pasted my log file below. Also I'm using eclipse with the standard project structure and have a copy of log4j.properties in both the root of the project folder and the bin folder. ### direct log messages to stdout ### #log4j.appender.stdout=org.apache.log4j.ConsoleAppender #log4j.appender.stdout.Target=System.out #log4j.appender.stdout.layout=org.apache.log4j.PatternLayout #log4j.appender.stdout.layout.ConversionPattern=%d{ABSOLUTE} %5p %c{1}:%L - %m%n ### direct messages to file hibernate.log ### log4j.appender.file=org.apache.log4j.FileAppender log4j.appender.file.File=hibernate.log log4j.appender.file.layout=org.apache.log4j.PatternLayout log4j.appender.file.layout.ConversionPattern=%d{ABSOLUTE} %5p %c{1}:%L - %m%n ### set log levels - for more verbose logging change 'info' to 'debug' ### log4j.rootLogger=warn, stdout #log4j.logger.org.hibernate=info log4j.logger.org.hibernate=debug ### log HQL query parser activity #log4j.logger.org.hibernate.hql.ast.AST=debug ### log just the SQL #log4j.logger.org.hibernate.SQL=debug ### log JDBC bind parameters ### log4j.logger.org.hibernate.type=info #log4j.logger.org.hibernate.type=debug ### log schema export/update ### log4j.logger.org.hibernate.tool.hbm2ddl=debug ### log HQL parse trees #log4j.logger.org.hibernate.hql=debug ### log cache activity ### #log4j.logger.org.hibernate.cache=debug ### log transaction activity #log4j.logger.org.hibernate.transaction=debug ### log JDBC resource acquisition #log4j.logger.org.hibernate.jdbc=debug ### enable the following line if you want to track down connection ### ### leakages when using DriverManagerConnectionProvider ### #log4j.logger.org.hibernate.connection.DriverManagerConnectionProvider=trac5

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  • how to convert byte array to key format??

    - by sebby_zml
    hi everyone, i would like to know how to convert byte array into key. i am doing an AES encryption/decryption. instead of generating a key, i would like to use my generated byte array. byte[] clientCK = Milenage.f3(sharedSecret16, RANDbytes, opc); let say i have a byte array called clientCK, stated above. i want to use it in AES encryption as shown below. Cipher c = Cipher.getInstance("AES"); c.init(Cipher.ENCRYPT_MODE, key); byte[] encValue = c.doFinal(valueToEnc.getBytes()); String encryptedValue = new BASE64Encoder().encode(encValue); therefore, i need to convert that byte array clientCK into key format. please help.

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  • Confused as to how to validate spring mvc form, what are my options?

    - by Blankman
    Latest spring mvc, using freemarker. Hoping someone could tell me what my options are in terms of validating a form with spring mvc, and what the recommend way would be to do this. I have a form that doesn't map directly to a model, it has input fields that when posted, will be used to initialze 2 model objects which I will then need to validate, and if they pass I will save them. If they fail, I want to return back to the form, pre-fill the values with what the user entered and display the error messages. I have read here and there about 2 methods, once of which I have done and understand how it works: @RequestMapping(...., method = RequestMethod.POST) public ModelAndView myMethod(@Valid MyModel, BindingResult bindingResult) { ModelAndView mav = new ModelAndView("some/view"); mav.addObject("mymodel", myModel); if(bindingResult.hasErrors()) { return mav; } } Now this worked if my form mapped directly to the form, but in my situation I have: form fields that don't map to any specific model, they have a few properties from 2 models. before validation occurrs, I need to create the 2 models manually, set the values from the values from the form, and manually set some properties also: Call validate on both models (model1, model2), and append these error messages to the errors collection which I need to pass back to the same view page if things don't work. when the form posts, I have to do some database calls, and based on those results may need to add additional messages to the errors collection Can someone tell me how to do this sort of validation? Pseudo code below: Model1 model1 = new Model1(); Model2 model2 = new Model2(); // manually or somehow automatically set the posted form values to model1 and model2. // set some fields manually, not from posted form model1.setProperty10(GlobalSettings.getDefaultProperty10()); model2.setProperty11(GlobalSettings.getDefaultProperty11()); // db calls, if they fail, add to errors collection if(bindingResult.hasErrors()) { return mav; } // validation passed, save Model1Service.save(model1); Model2Service.save(model2); redirect to another view Update I have using the JSR 303 annotations on my models right now, and it would great if I can use those still. Update II Please read the bounty description below for a summary of what I am looking for.

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  • How to increase detail band height dynamically

    - by Chandu
    Hi All, I am using ireport. My requirement is to increase the detail band height dynamically when the text field has more data , are there any settings to increase to it? I am using one textfield in the detail band when it has more information(words), it is displaying only some information.i.e the words are being cut off. Depending on the detail band height the words are displaying.I would like to increase the band hieght dynamically when the text field has more data. Please advice me on this regard. Regards, Chandu

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  • simpledateformat parsing date with 'Z' literal

    - by DanInDC
    I am trying to parse a date that looks like this: 2010-04-05T17:16:00Z This is a valid date per http://www.ietf.org/rfc/rfc3339.txt. The 'Z' literal "imply that UTC is the preferred reference point for the specified time." If I try to parse it using SimpleDateFormat and this pattern: yyyy-MM-dd'T'HH:mm:ss It will be parsed as a Mon Apr 05 17:16:00 EDT 2010 SimpleDateFormat is unable to parse the string with these patterns: yyyy-MM-dd'T'HH:mm:ssz yyyy-MM-dd'T'HH:mm:ssZ I can explicitly set the TimeZone to use on the SimpleDateFormat to get the expected output, but I don't think that should be necessary. Is there something I am missing? Is there an alternative date parser?

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  • Javas Math.sin() produces NaN all the time

    - by milan1612
    Forgive me if this is a dumb beginners problem, but I really don't get it. I have a member variable declared like so: public Double Value; When I assign 3.14159265 to Value and try to compute the sine of it, this happens: system.out.println(Value.toString()); //outputs 3.14159265 Value = Math.sin(Value); system.out.println(Value.toString()); //outputs NaN In fact, this happens with every single value I tried - even with 0! Math.sin() seems to always produce NaN as a result, regardless of the arguments value. The docs say: If the argument is NaN or an infinity, then the result is NaN. But my argument is clearly not NaN or infinity! What the heck is happening there?

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