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  • The way cores, processes, and threads work exactly?

    - by unknownthreat
    I need a bit of an advice for understanding how this whole procedure work exactly. If I am incorrect in any part described below, please correct me. In a single core CPU, it runs each process in the OS, jumping around from one process to another to utilize the best of itself. A process can also have many threads, in which the CPU core runs through these threads when it is running on the respective process. Now, on a multiple core CPU, Do the cores run in every process together, or can the cores run separately in different processes at one particular point of time? For instance, you have program A running two threads, can a duo core CPU run both threads of this program? I think the answer should be yes if we are using something like OpenMP. But while the cores are running in this OpenMP-embedded process, can one of the core simply switch to other process? For programs that are created for single core, when running at 100%, why the CPU utilization of each core are distributed? (ex. A duo core CPU of 80% and 20%. The utilization percentage of all cores always add up to 100% for this case.) Do the cores try help each other run each thread of each process in some ways? Frankly, I'm not sure how this works exactly. Any advice is appreciated.

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  • How to amend return value design in OO manner?

    - by FrontierPsycho
    Hello. I am no newb on OO programming, but I am faced with a puzzling situation. I have been given a program to work on and extend, but the previous developers didn't seem that comfortable with OO, it seems they either had a C background or an unclear understanding of OO. Now, I don't suggest I am a better developer, I just think that I can spot some common OO errors. The difficult task is how to amend them. In my case, I see a lot of this: if (ret == 1) { out.print("yadda yadda"); } else if (ret == 2) { out.print("yadda yadda"); } else if (ret == 3) { out.print("yadda yadda"); } else if (ret == 0) { out.print("yadda yadda"); } else if (ret == 5) { out.print("yadda yadda"); } else if (ret == 6) { out.print("yadda yadda"); } else if (ret == 7) { out.print("yadda yadda"); } ret is a value returned by a function, in which all Exceptions are swallowed, and in the catch blocks, the above values are returned explicitly. Oftentimes, the Exceptions are simply swallowed, with empty catch blocks. It's obvious that swalllowing exceptions is wrong OO design. My question concerns the use of return values. I believe that too is wrong, however I think that using Exceptions for control flow is equally wrong, and I can't think of anything to replace the above in a correct, OO manner. Your input, please?

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  • How do I close a file after catching an IOException in java?

    - by DimDom
    All, I am trying to ensure that a file I have open with BufferedReader is closed when I catch an IOException, but it appears as if my BufferedReader object is out of scope in the catch block. public static ArrayList readFiletoArrayList(String fileName, ArrayList fileArrayList) { fileArrayList.removeAll(fileArrayList); try { //open the file for reading BufferedReader fileIn = new BufferedReader(new FileReader(fileName)); // add line by line to array list, until end of file is reached // when buffered reader returns null (todo). while(true){ fileArrayList.add(fileIn.readLine()); } }catch(IOException e){ fileArrayList.removeAll(fileArrayList); fileIn.close(); return fileArrayList; //returned empty. Dealt with in calling code. } } Netbeans complains that it "cannot find symbol fileIn" in the catch block, but I want to ensure that in the case of an IOException that the Reader gets closed. How can I do that without the ugliness of a second try/catch construct around the first? Any tips or pointers as to best practise in this situation is appreciated,

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  • C++ BigInt multiplication conceptual problem

    - by Kapo
    I'm building a small BigInt library in C++ for use in my programming language. The structure is like the following: short digits[ 1000 ]; int len; I have a function that converts a string into a bigint by splitting it up into single chars and putting them into digits. The numbers in digits are all reversed, so the number 123 would look like the following: digits[0]=3 digits[1]=3 digits[2]=1 I have already managed to code the adding function, which works perfectly. It works somewhat like this: overflow = 0 for i ++ until length of both numbers exceeded: add numberA[ i ] to numberB[ i ] add overflow to the result set overflow to 0 if the result is bigger than 10: substract 10 from the result overflow = 1 put the result into numberReturn[ i ] (Overflow is in this case what happens when I add 1 to 9: Substract 10 from 10, add 1 to overflow, overflow gets added to the next digit) So think of how two numbers are stored, like those: 0 | 1 | 2 --------- A 2 - - B 0 0 1 The above represents the digits of the bigints 2 (A) and 100 (B). - means uninitialized digits, they aren't accessed. So adding the above number works fine: start at 0, add 2 + 0, go to 1, add 0, go to 2, add 1 But: When I want to do multiplication with the above structure, my program ends up doing the following: Start at 0, multiply 2 with 0 (eek), go to 1, ... So it is obvious that, for multiplication, I have to get an order like this: 0 | 1 | 2 --------- A - - 2 B 0 0 1 Then, everything would be clear: Start at 0, multiply 0 with 0, go to 1, multiply 0 with 0, go to 2, multiply 1 with 2 How can I manage to get digits into the correct form for multiplication? I don't want to do any array moving/flipping - I need performance!

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  • RMagick transparent_color deprecated? What's the alternative?

    - by user315975
    I'm developing an app that does a fair amount of generating transparent pngs on the fly. These are used as overlays, to show areas of interest in a graphic, so they have to have transparent backgrounds. I am developing in Ruby on Rails, deploying on Heroku. What works fine in development is not working in production. I get this error when I call a drawing routine using RMagick: NotImplementedError (the `transparent_color=' method is not supported by ImageMagick 6.2.4): /usr/local/lib/ruby/gems/1.8/gems/rmagick-1.15.17/lib/RMagick.rb:1691:in `transparent_color=' I'm using RMagick version 2.12.1 on the development machine, but I'm not exactly certain how to discover the version of ImageMagick that it's running, so I'm not sure if this is a case of my local code being behind or ahead. I'm hoping behind, because perhaps then there'll be a replacement for this call. Does anyone know what the fix is here? What's required to generate a transparent background, if not the call I'm using? I can't find this in the documentation: in fact, it was on a third-party site that I found mention of this capability.

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  • How to configure Server Topology for exposing an internal application for external access?

    - by ronaldwidha
    Hi All, I guess this question is bordering to a Server Fault question. I'd like to know the best configuration for exposing an internal application (in this case a load balanced Asp.Net MVC application) for external access. More details about the situation: The Asp.Net MVC Application is currently running on 2 servers The 2 servers are behind a Windows Network Load Balancer All the servers are on premise/internal network I'm thinking of introducing an F5 Load balancer on off premise DMZ to replace the Windows Network Load Balancer. F5 will act as the public traffic gateway and load balancers to the 2 servers. However, I'd like the internal users to not have go through the Internet to access the app. The idea that I have so far is to keep both Windows Network Load Balancer and the F5. Each appliance will have its own IP and will have its own domain name. External users can use the public domain name which will hit F5, whereas internal users can use the internal domain name which will hit the Windows Network Load Balancer. Is this a good idea? Or is there a better way of doing this?

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  • Unit Testing - Algorithm or Sample based ?

    - by ohadsc
    Say I'm trying to test a simple Set class public IntSet : IEnumerable<int> { Add(int i) {...} //IEnumerable implementation... } And suppose I'm trying to test that no duplicate values can exist in the set. My first option is to insert some sample data into the set, and test for duplicates using my knowledge of the data I used, for example: //OPTION 1 void InsertDuplicateValues_OnlyOneInstancePerValueShouldBeInTheSet() { var set = new IntSet(); //3 will be added 3 times var values = new List<int> {1, 2, 3, 3, 3, 4, 5}; foreach (int i in values) set.Add(i); //I know 3 is the only candidate to appear multiple times int counter = 0; foreach (int i in set) if (i == 3) counter++; Assert.AreEqual(1, counter); } My second option is to test for my condition generically: //OPTION 2 void InsertDuplicateValues_OnlyOneInstancePerValueShouldBeInTheSet() { var set = new IntSet(); //The following could even be a list of random numbers with a duplicate var values = new List<int> { 1, 2, 3, 3, 3, 4, 5}; foreach (int i in values) set.Add(i); //I am not using my prior knowledge of the sample data //the following line would work for any data CollectionAssert.AreEquivalent(new HashSet<int>(values), set); } Of course, in this example, I conveniently have a set implementation to check against, as well as code to compare collections (CollectionAssert). But what if I didn't have either ? This is the situation when you are testing your real life custom business logic. Granted, testing for expected conditions generically covers more cases - but it becomes very similar to implementing the logic again (which is both tedious and useless - you can't use the same code to check itself!). Basically I'm asking whether my tests should look like "insert 1, 2, 3 then check something about 3" or "insert 1, 2, 3 and check for something in general" EDIT - To help me understand, please state in your answer if you prefer OPTION 1 or OPTION 2 (or neither, or that it depends on the case, etc )

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  • Releasing Autopool crashes on iOS 4.0 (and only on 4.0)

    - by samsam
    Hi there. I'm wondering what could cause this. I have several methods in my code that i call using performSelectorInBackground. Within each of these methods i have an Autoreleasepool that is being alloced/initialized at the beginning and released at the end of the method. this perfectly works on iOS 3.1.3 / 3.2 / 4.2 / 4.2.1 but it fataly crashes on iOS 4.0 with a EXC_BAD_ACCESS Exception that happens after calling [myPool release]. After I noticed this strange behaviour I was thinking about rewriting portions of my code and to make my app "less parallel" in case that the client os is 4.0. After I did that, the next point where the app crashed was within the ReachabilityCallback-Method from Apples Reachability "Framework". well, now I'm not quite sure what to do. The things i do within my threaded methods is pretty simple xml parsing (no cocoa calls or stuff that would affect the UI). After each method finishes it posts a notification which the coordinating-thread listens to and once all the parallelized methods have finished, the coordinating thread calls viewcontrollers etc... I have absolutely no clue what could cause this weird behaviour. Especially because Apples Code fails as well. any help is greatly appreciated! thanks, sam

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  • What are the best tricks for learning how to -think- in Objective-C?

    - by Braintapper
    Before I get flamed out for not checking previous questions, I have read most of the tutorials, and have Hillegass' book, as well as O'Reilly's book on it. I'm not asking for tips on Cocoa or what IDE to use. Where my issue lies - my 'mental muscle memory' is making it hard for me to read Objective-C code. I have no problems at all reading Java and C code and understanding what's going on. Maybe I'm getting to old to learn a new syntax, but it's a struggle shifting mental gears and looking at Objective-C code and just "getting it" (I thought it might be an isolated case, but I have other friends who are seasoned devs who have said the same thing). Are there any tricks that any non-Objective-C programmers who now know Objective-C used to help process the syntactical differences when learning it? For some reason, I get dyslexic when reading Objective-C code. Maybe I'm not meant to be able to learn it (and that's ok too). I was hoping/wondering if there might be others who have had the same experience.

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  • How do I prevent a branch from being pushed to another branch in BZR?

    - by cabbey
    We use a dev-test-prod branching scheme with bzr 2. I'd like to setup a bzr hook on the prod branch that will reject a push from the test branch. Looking at the bzr docs, this looks doable, but I'm kinda surprised that my searches don't turn up any one having done it, at least not via any of the keywords I've thought to search by. I'm hoping someone has already gotten this working and can share their path to success. My current thought is to use the pre_change_branch_tip hook to check for the presence of a file on the test branch. If it's present, fail the commit. You may ask, why test for a file, why not just test the branch name? Because I actually need to handle the case where our developers have branched their devel branch, pulled in the shared test branch and are now (erroneously) pushing that test branch to production instead of pushing their feature branch to production. And it seems a billion times easier to look for a file in the new branch than to try to interrogate the sending branch's lineage. So has someone done this? seen it done? or do I get to venture out into the uncharted wasteland that is hook development with bzr? :)

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  • SQL Group by Minute- Expanded

    - by Barnie
    I am working on something similar to this post here: TS SQL - group by minute However mine is pulling from an message queue, and I need to see an accurate count of the amount of traffic the Message Queue is creating/ sending, and at what time Select * From MessageQueue mq My expanded version of this though is the following: A) User defines a start time and an end time (Easy enough using Declare's @StartTime and @EndTime B) Give the user the option of choosing the "grouping". Will it be broken out by 1 minutes, 5 minutes, 15 minutes, or 30 minutes (Max). (I had thought to do this with a CASE statement, but my test problems fall apart on me.) C) Display the data to accurately show a count of what happened during the interval (Grouping) selected. This is where I am at so far SQL Blob: DECLARE @StartTime datetime DECLARE @EndTime datetime SELECT DATEPART(n, mq.cre_date)/5 as Time --Trying to just sort by 5 minute intervals ,CONVERT(VARCHAR(10),mq.Cre_Date,101) ,COUNT(*) as results FROM dbo.MessageQueue mq WHERE mq.cre_date BETWEEN @StartDate AND @EndDate GROUP BY DATEPART(n, mq.cre_date)/5 --Trying to just sort by 5 minute intervals , eq.Cre_Date This is the output I would like to achieve: [Time] [Date] [Message Count] 1300 06/26/2012 5 1305 06/26/2012 1 1310 06/26/2012 100

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  • Difference between two PHP times as years, months and days for PHP version 5.2

    - by Dominor Novus
    Forward: I've scanned through the existing questions/answers on this matter. This is not a duplicitous question; I cannot find a working solution from the accepted answers. The main questions/answers I've reviewed can be found here: How to calculate the difference between two dates using PHP? What I need: A calucalation of the difference between two dates expressed as years, months and days that works with PHP version: 5.2. <?php $current_date = date('d-M-Y'); $future_date = '2012-11-01'; ?> What I've tried: Most answers I find online don't seem to exact in that they don't factor in leap years. This highly rated answer won't work because DateTime-diff() is php 5.3+. This accepted answer results in (i.e. the second block of code aimed at PHP 5.2) results in the following being parsed: Array ( [y] = 25 [m] = 11 [d] = 7 [h] = 3 [i] = 15 [s] = 19 [invert] = 0 [days] = 9473 ) Array ( [y] = 25 [m] = 11 [d] = 7 [h] = 3 [i] = 15 [s] = 19 [invert] = 1 [days] = 9473 ) I can't tell if I've incorrectly applied the code or it's simply a case of me not knowing how to manipulate the array.

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  • jQuery: How to use modifier keys on form submit?

    - by Svish
    Say I have a form that looks like this: [ Animal name input field ] Add button If I type a name and hit enter, an animal with the given name is added to a table. Works fine. What I would like now is to call the current way of working "quick add" and add a new feature called "slow add", which I am not quite sure how to do. Basically what I want is that if for example the shift key is held down when enter or the button is clicked, I want the form submit method to do something slightly different. In my case I want it to open up a form where more details on the animal can be added before it is added to the table. Problem is I'm not quite sure how to do this. I have tried add a FireBug console.info(eventData) in my current submit function and I have found that the eventData contains an altKey, shiftKey and controlKey property, but they are always undefined even when I hold those keys down. So, does anyone know how I can do something special in my submit handler when certain modifier keys were pressed when the form was submitted?

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  • Inefficient 'ANY' LINQ clause

    - by Focus
    I have a query that pulls back a user's "feed" which is essentially all of their activity. If the user is logged in the query will be filtered so that the feed not only includes all of the specified user's data, but also any of their friends. The database structure includes an Actions table that holds the user that created the action and a UserFriends table which holds any pairing of friends using a FrienderId and FriendeeId column which map to UserIds. I have set up my LINQ query and it works fine to pull back the data I want, however, I noticed that the query gets turned into X number of CASE clauses in profiler where X is the number of total Actions in the database. This will obviously be horrible when the database has a user base larger than just me and 3 test users. Here's the SQL query I'm trying to achieve: select * from [Action] a where a.UserId = 'GUID' OR a.UserId in (SELECT FriendeeId from UserFriends uf where uf.FrienderId = 'GUID') OR a.UserId in (SELECT FrienderId from UserFriends uf where uf.FriendeeId = 'GUID') This is what I currently have as my LINQ query. feed = feed.Where(o => o.User.UserKey == user.UserKey || db.Users.Any(u => u.UserFriends.Any(ufr => ufr.Friender.UserKey == user.UserKey && ufr.isApproved) || db.Users.Any(u2 => u2.UserFriends.Any(ufr => ufr.Friendee.UserKey == user.UserKey && ufr.isApproved) ))); This query creates this: http://pastebin.com/UQhT90wh That shows up X times in the profile trace, once for each Action in the table. What am I doing wrong? Is there any way to clean this up?

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  • Concrete examples of state sharing between multiple viewmodels (WPF MVVM)

    - by JohnMetta
    I have a WPF/Entity Framework (4.0) project with many objects. I'd like to build the application so that that I can have object selection state shared across viewmodels. For Example: We have Cars, Drivers, Passengers, and Cargo classes. We also have UserControls for CarList, DriverList, etc. and editor windows for CarEditor, DriverEditor, etc. Furthermore, we have viewmodels for all of these (CarListViewModel, DriverListViewModel, CargoEditorViewModel, etc). This all composes a dockable interface where the user can have multiple object lists, editors, and viewers open. What I want is a concrete code example of how to wireup multiple viewmodels so that selecting a car in the CarList will cause that car to go live in the CarEditorView, but also be selected in any other view for which the context is valid (such as a DriverByCarView- or just DriverList if there is a filter predicate). There are a number of suggestions and discussions based on this question. The two methods that seem to dominate are: 3018307: Discusses state sharing by mentioning a messaging subsystem 1159035: Discusses state sharing by using an enclosing viewmodel Is one of these approaches better than the other? Does anyone have a concrete example of either/both of these methods in the form of a write-up or small code project? I'm still learning WPF, so pointers to entry points for reading API fundamentals are appreciated, but looking at code examples is where I usually go. Thanks In case anyone is interested, here are some other similar discussions: 3816961: Discusses returning multiple viewmodels depending on object type (i.e. a collection of arbitrary types adhering to a specific interface) 1928130: Discusses whether it is a good idea to aggregate viewmodels as properties of other viewmodels (e.g. a MainWindow viewmodel composed of panel viewmodels) 1120061: Essentially discusses whether to have use a viewmodel-per-model strategy or a viewmodel-per-view-element strategy. 4244222: Discusses whether or not to nest the viewmodels when using a nested object hierarchy. 4429708: Discusses sharing collections between viewmodels directly, but doesn't go into detail. List item: Discusses managing multiple selections within a single viewmodel.

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  • What are these stray zero-byte files extracted from tarball? (OSX)

    - by Scott M
    I'm extracting a folder from a tarball, and I see these zero-byte files showing up in the result (where they are not in the source.) Setup (all on OS X): On machine one, I have a directory /My/Stuff/Goes/Here/ containing several hundred files. I build it like this tar -cZf mystuff.tgz /My/Stuff/Goes/Here/ On machine two, I scp the tgz file to my local directory, then unpack it. tar -xZf mystuff.tgz It creates ~scott/My/Stuff/Goes/, but then under Goes, I see two files: Here/ - a directory, Here.bGd - a zero byte file. The "Here.bGd" zero-byte file has a random 3-character suffix, mixed upper and lower-case characters. It has the same name as the lowest-level directory mentioned in the tar-creation command. It only appears at the lowest level directory named. Anybody know where these come from, and how I can adjust my tar creation to get rid of them? Update: I checked the table of contents on the files using tar tZvf: toc does not list the zero-byte files, so I'm leaning toward the suggestion that the uncompress machine is at fault. OS X is version 10.5.5 on the unzip machine (not sure how to check the filesystem type). Tar is GNU tar 1.15.1, and it came with the machine.

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  • Are there any less costly alternatives to Amazon's Relational Database Services (RDS)?

    - by swapnonil
    Hi All, I have the following requirement. I have with me a database containing the contact and address details of at least 2000 members of my school alumni organization. We want to store all that information in a relation model so that This data can be created and edited on demand. This data is always backed up and should be simple to restore in case the master copy becomes unusable. All sensitive personal information residing in this database is guaranteed to be available only to authorized users. This database won't be online in the first 6 months. It will become online only after a website is built on top of it. I am not a DBA and I don't want to spend time doing things like backups. I thought Amazon's RDS with it's automatic backup facility was the perfect solution for our needs. The only problem is that being a voluntary organization we cannot spare the monthly $100 to $150 fees this service demands. So my question is, are there any less costlier alternatives to Amazon's RDS?

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  • Java Class<T> static method forName() IncompatibleClassChangeError

    - by matt
    Hi, i have this code: private static Importable getRightInstance(String s) throws Exception { Class<? extends Importable> c = Class.forName(s).asSubclass(Importable.class); Importable i = c.newInstance(); return i; } which i can also write private static Importable getRightInstance(String s) throws Exception { Class<? extends Importable> c = (Class<? extends Importable>)Class.forName(s); Importable i = c.newInstance(); return i; } or private static Importable getRightInstance(String s) throws Exception { Class<?> c = Class.forName(s); Importable i = (Importable)c.newInstance(); return i; } where Importable is an interface and s is a string representing an implementing class. Well, in any case it gives the following: Exception in thread "main" java.lang.IncompatibleClassChangeError: class C1 has interface Importable as super class Here is the last snippet of the stack trace: at java.lang.Class.forName(Class.java:169) at Importer.getRightImportable(Importer.java:33) at Importer.importAll(Importer.java:44) at Test.main(Test.java:16) Now, class C1 actually implemens Importable and i totally don't understand why it complaints. Thanks in advance.

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  • Avoid using InetAddress - Getting a raw IP address in network byte order

    - by Mylo
    Hey, I am trying to use the MaxMind GeoLite Country database on the Google App Engine. However, I am having difficulty getting the Java API to work as it relies on the InetAddress class which is not available to use on the App Engine. However, I am not sure if there is a simple workaround as it appears it only uses the InetAddress class to determine the IP of a given hostname. In my case, the hostname is always an IP anyway. What I need is a way to convert an IP address represented as a String into a byte array of network byte order (which the addr.getAddress() method of the InetAddress class provides). This is the code the current API uses, I need to find a way of removing all references to InetAddress whilst ensuring it still works! Thanks for your time. /** * Returns the country the IP address is in. * * @param ipAddress String version of an IP address, i.e. "127.0.0.1" * @return the country the IP address is from. */ public Country getCountry(String ipAddress) { InetAddress addr; try { addr = InetAddress.getByName(ipAddress); } catch (UnknownHostException e) { return UNKNOWN_COUNTRY; } return getCountry(bytesToLong(addr.getAddress())); }

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  • jquery form validation, and submit-on-change

    - by Bee
    I want to make all my settings forms across my site confirm that changes are saved, kinda like facebook does if you make changes in a form and then try to navigate away without saving. So I'm disabling the submit button on the forms only enabling if the values change. I then prompt the user to hit save before they leave the page in the case that they do have changes pending. var form = $('form.edit'); if(form.length > 0) { var orig_str = form.serialize(); $(':submit',form).attr('disabled','disabled'); form.on('change keyup', function(){ if(form.serialize() == orig_str) { setConfirmUnload(false); $(':submit',form).attr('disabled','disabled'); } else { setConfirmUnload(true); $(':submit',form).removeAttr('disabled') } }); $('input[type=submit]').click(function(){ setConfirmUnload(false); }); } function setConfirmUnload(on) { window.onbeforeunload = (on) ? unloadMessage : null; } function unloadMessage() { return 'If you navigate away from this page without saving your changes, they will be lost.'; } One of these forms needs some additional validation which I do using jQuery.validate library. e.g. if i wanted to ensure the user can't double submit the form on accident by double clicking on submit or somesuch (the actual validation in question is for a credit-card form and not this simple): $('form').validate({ submitHandler: function(form) { $(':submit', form).attr('disabled','disabled'); form.submit(); } }); Unfortunately both bits are trying to bind to submit button and they're interfering with each other such that the submit button remains disabled no matter what I do and it is impossible to submit the form at all. Is there some way to chain the validations together or something? Or some other way to avoid re-writing the validation code to repeat the "did you change anything in the form" business?

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  • Delphi: EInvalidOp in neural network class (TD-lambda)

    - by user89818
    I have the following draft for a neural network class. This neural network should learn with TD-lambda. It is started by calling the getRating() function. But unfortunately, there is an EInvalidOp (invalid floading point operation) error after about 1000 iterations in the following lines: neuronsHidden[j] := neuronsHidden[j]+neuronsInput[t][i]*weightsInput[i][j]; // input -> hidden weightsHidden[j][k] := weightsHidden[j][k]+LEARNING_RATE_HIDDEN*tdError[k]*eligibilityTraceOutput[j][k]; // adjust hidden->output weights according to TD-lambda Why is this error? I can't find the mistake in my code :( Can you help me? Thank you very much in advance! unit uNeuronalesNetz; interface uses Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms, Dialogs, ExtCtrls, StdCtrls, Grids, Menus, Math; const NEURONS_INPUT = 43; // number of neurons in the input layer NEURONS_HIDDEN = 60; // number of neurons in the hidden layer NEURONS_OUTPUT = 1; // number of neurons in the output layer NEURONS_TOTAL = NEURONS_INPUT+NEURONS_HIDDEN+NEURONS_OUTPUT; // total number of neurons in the network MAX_TIMESTEPS = 42; // maximum number of timesteps possible (after 42 moves: board is full) LEARNING_RATE_INPUT = 0.25; // in ideal case: decrease gradually in course of training LEARNING_RATE_HIDDEN = 0.15; // in ideal case: decrease gradually in course of training GAMMA = 0.9; LAMBDA = 0.7; // decay parameter for eligibility traces type TFeatureVector = Array[1..43] of SmallInt; // definition of the array type TFeatureVector TArtificialNeuralNetwork = class // definition of the class TArtificialNeuralNetwork private // GENERAL SETTINGS START learningMode: Boolean; // does the network learn and change its weights? // GENERAL SETTINGS END // NETWORK CONFIGURATION START neuronsInput: Array[1..MAX_TIMESTEPS] of Array[1..NEURONS_INPUT] of Extended; // array of all input neurons (their values) for every timestep neuronsHidden: Array[1..NEURONS_HIDDEN] of Extended; // array of all hidden neurons (their values) neuronsOutput: Array[1..NEURONS_OUTPUT] of Extended; // array of output neurons (their values) weightsInput: Array[1..NEURONS_INPUT] of Array[1..NEURONS_HIDDEN] of Extended; // array of weights: input->hidden weightsHidden: Array[1..NEURONS_HIDDEN] of Array[1..NEURONS_OUTPUT] of Extended; // array of weights: hidden->output // NETWORK CONFIGURATION END // LEARNING SETTINGS START outputBefore: Array[1..NEURONS_OUTPUT] of Extended; // the network's output value in the last timestep (the one before) eligibilityTraceHidden: Array[1..NEURONS_INPUT] of Array[1..NEURONS_HIDDEN] of Array[1..NEURONS_OUTPUT] of Extended; // array of eligibility traces: hidden layer eligibilityTraceOutput: Array[1..NEURONS_TOTAL] of Array[1..NEURONS_TOTAL] of Extended; // array of eligibility traces: output layer reward: Array[1..MAX_TIMESTEPS] of Array[1..NEURONS_OUTPUT] of Extended; // the reward value for all output neurons in every timestep tdError: Array[1..NEURONS_OUTPUT] of Extended; // the network's error value for every single output neuron t: Byte; // current timestep cyclesTrained: Integer; // number of cycles trained so far (learning rates could be decreased accordingly) last50errors: Array[1..50] of Extended; // LEARNING SETTINGS END public constructor Create; // create the network object and do the initialization procedure UpdateEligibilityTraces; // update the eligibility traces for the hidden and output layer procedure tdLearning; // learning algorithm: adjust the network's weights procedure ForwardPropagation; // propagate the input values through the network to the output layer function getRating(state: TFeatureVector; explorative: Boolean): Extended; // get the rating for a given state (feature vector) function HyperbolicTangent(x: Extended): Extended; // calculate the hyperbolic tangent [-1;1] procedure StartNewCycle; // start a new cycle with everything set to default except for the weights procedure setLearningMode(activated: Boolean=TRUE); // switch the learning mode on/off procedure setInputs(state: TFeatureVector); // transfer the given feature vector to the input layer (set input neurons' values) procedure setReward(currentReward: SmallInt); // set the reward for the current timestep (with learning then or without) procedure nextTimeStep; // increase timestep t function getCyclesTrained(): Integer; // get the number of cycles trained so far procedure Visualize(imgHidden: Pointer); // visualize the neural network's hidden layer end; implementation procedure TArtificialNeuralNetwork.UpdateEligibilityTraces; var i, j, k: Integer; begin // how worthy is a weight to be adjusted? for j := 1 to NEURONS_HIDDEN do begin for k := 1 to NEURONS_OUTPUT do begin eligibilityTraceOutput[j][k] := LAMBDA*eligibilityTraceOutput[j][k]+(neuronsOutput[k]*(1-neuronsOutput[k]))*neuronsHidden[j]; for i := 1 to NEURONS_INPUT do begin eligibilityTraceHidden[i][j][k] := LAMBDA*eligibilityTraceHidden[i][j][k]+(neuronsOutput[k]*(1-neuronsOutput[k]))*weightsHidden[j][k]*neuronsHidden[j]*(1-neuronsHidden[j])*neuronsInput[t][i]; end; end; end; end; procedure TArtificialNeuralNetwork.setReward; VAR i: Integer; begin for i := 1 to NEURONS_OUTPUT do begin // +1 = player A wins // 0 = draw // -1 = player B wins reward[t][i] := currentReward; end; end; procedure TArtificialNeuralNetwork.tdLearning; var i, j, k: Integer; begin if learningMode then begin for k := 1 to NEURONS_OUTPUT do begin if reward[t][k] = 0 then begin tdError[k] := GAMMA*neuronsOutput[k]-outputBefore[k]; // network's error value when reward is 0 end else begin tdError[k] := reward[t][k]-outputBefore[k]; // network's error value in the final state (reward received) end; for j := 1 to NEURONS_HIDDEN do begin weightsHidden[j][k] := weightsHidden[j][k]+LEARNING_RATE_HIDDEN*tdError[k]*eligibilityTraceOutput[j][k]; // adjust hidden->output weights according to TD-lambda for i := 1 to NEURONS_INPUT do begin weightsInput[i][j] := weightsInput[i][j]+LEARNING_RATE_INPUT*tdError[k]*eligibilityTraceHidden[i][j][k]; // adjust input->hidden weights according to TD-lambda end; end; end; end; end; procedure TArtificialNeuralNetwork.ForwardPropagation; var i, j, k: Integer; begin for j := 1 to NEURONS_HIDDEN do begin neuronsHidden[j] := 0; for i := 1 to NEURONS_INPUT do begin neuronsHidden[j] := neuronsHidden[j]+neuronsInput[t][i]*weightsInput[i][j]; // input -> hidden end; neuronsHidden[j] := HyperbolicTangent(neuronsHidden[j]); // activation of hidden neuron j end; for k := 1 to NEURONS_OUTPUT do begin neuronsOutput[k] := 0; for j := 1 to NEURONS_HIDDEN do begin neuronsOutput[k] := neuronsOutput[k]+neuronsHidden[j]*weightsHidden[j][k]; // hidden -> output end; neuronsOutput[k] := HyperbolicTangent(neuronsOutput[k]); // activation of output neuron k end; end; procedure TArtificialNeuralNetwork.setLearningMode; begin learningMode := activated; end; constructor TArtificialNeuralNetwork.Create; var i, j, k: Integer; begin inherited Create; Randomize; // initialize random numbers generator learningMode := TRUE; cyclesTrained := -2; // only set to -2 because it will be increased twice in the beginning StartNewCycle; for j := 1 to NEURONS_HIDDEN do begin for k := 1 to NEURONS_OUTPUT do begin weightsHidden[j][k] := abs(Random-0.5); // initialize weights: 0 <= random < 0.5 end; for i := 1 to NEURONS_INPUT do begin weightsInput[i][j] := abs(Random-0.5); // initialize weights: 0 <= random < 0.5 end; end; for i := 1 to 50 do begin last50errors[i] := 0; end; end; procedure TArtificialNeuralNetwork.nextTimeStep; begin t := t+1; end; procedure TArtificialNeuralNetwork.StartNewCycle; var i, j, k, m: Integer; begin t := 1; // start in timestep 1 cyclesTrained := cyclesTrained+1; // increase the number of cycles trained so far for j := 1 to NEURONS_HIDDEN do begin neuronsHidden[j] := 0; for k := 1 to NEURONS_OUTPUT do begin eligibilityTraceOutput[j][k] := 0; outputBefore[k] := 0; neuronsOutput[k] := 0; for m := 1 to MAX_TIMESTEPS do begin reward[m][k] := 0; end; end; for i := 1 to NEURONS_INPUT do begin for k := 1 to NEURONS_OUTPUT do begin eligibilityTraceHidden[i][j][k] := 0; end; end; end; end; function TArtificialNeuralNetwork.getCyclesTrained; begin result := cyclesTrained; end; procedure TArtificialNeuralNetwork.setInputs; var k: Integer; begin for k := 1 to NEURONS_INPUT do begin neuronsInput[t][k] := state[k]; end; end; function TArtificialNeuralNetwork.getRating; begin setInputs(state); ForwardPropagation; result := neuronsOutput[1]; if not explorative then begin tdLearning; // adjust the weights according to TD-lambda ForwardPropagation; // calculate the network's output again outputBefore[1] := neuronsOutput[1]; // set outputBefore which will then be used in the next timestep UpdateEligibilityTraces; // update the eligibility traces for the next timestep nextTimeStep; // go to the next timestep end; end; function TArtificialNeuralNetwork.HyperbolicTangent; begin if x > 5500 then // prevent overflow result := 1 else result := (Exp(2*x)-1)/(Exp(2*x)+1); end; end.

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