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  • Math: How to sum each row of a matrix

    - by macek
    I have a 1x8 matrix of students where each student is a 4x1 matrix of scores. Something like: SCORES S [62, 91, 74, 14] T [59, 7 , 59, 21] U [44, 9 , 69, 6 ] D [4 , 32, 28, 53] E [78, 99, 53, 83] N [48, 86, 89, 60] T [56, 71, 15, 80] S [47, 67, 79, 40] Main question: Using sigma notation, or some other mathematical function, how can I get a 1x8 matrix where each student's scores are summed? # expected result TOTAL OF SCORES S [241] T [146] U [128] D [117] E [313] N [283] T [222] S [233] Sub question. To get the average, I will multiply the matrix by 1/4. Would there be a quicker way to get the final result? AVERAGE SCORE S [60.25] T [36.50] U [32.00] D [29.25] E [78.25] N [70.75] T [55.50] S [58.25] Note: I'm not looking for programming-related algorithms here. I want to know if it is possible to represent this with pure mathematical functions alone.

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  • Sum of path products in DAG

    - by Jules
    Suppose we have a DAG with edges labeled with numbers. Define the value of a path as the product of the labels. For each (source,sink)-pair I want to find the sum of the values of all the paths from source to sink. You can do this in polynomial time with dynamic programming, but there are still some choices that can be made in how you decompose the problem. In my case I have one DAG that has to be evaluated repeatedly with different labelings. My question is: for a given DAG, how can we pre-compute a good strategy for computing these values for different labelings repeatedly. It would be nice if there was an algorithm that finds an optimal way, for example a way that minimizes the number of multiplications. But perhaps this is too much to ask, I would be very happy with an algorithm that just gives a good decomposition.

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  • Setting up a home server - what to use? (ZFS vs btrfs, BSD vs Linux, misc other requirements)

    - by monch1962
    I need to get all our home content off individual machines and onto a central server. What I'd like to have is the metaphorical "server under the stairs". Stuff we need: expandable storage. I want to be able to add extra disc as we go along, with minimal maintenance required. Currently we've got about 3Tb of files we need to host, and that's likely to grow by another Tb every 6-12 months based on recent history. I need to be able to add additional disc with minimal pain needs to store all the media (i.e. photos, video, music) we have, and run services to serve the various devices we have in the house to playback (e.g. DAAP so we can play stuff through iTunes, ccxstream so we can play stuff over XBMC). DAAP and ccxstream are needed now, but we also need to support new standards as they emerge (so a closed-box solution isn't going to work) RAID 5, or something broadly equivalent (e.g. RAID-Z) BitTorrent client ssh, NFS, Samba access snapshot capability (as in ZFS), so we can snapshot individual file systems regularly and rollback when my kids delete their school assignments the day before they're due... ability to recover quickly from power outages (it's not unusual for us to have power outages that last longer than our UPS' batteries) FOSS software a modern distributed version control system running on the box, such as Mercurial Stuff I'd like to have on the server, but can live without: PVR capability, so I could record TV to the box Web server. We currently run a small Web server on a very old box, and I'd ideally like to turn the old box off and move the content to the new server just to save some electricity Nagios + mrtg I've been looking at using a EEE Box as the server, primarily because I can get them cheap and they don't consume much power. The choice of OS and file system is more difficult, from what I've found: I've got most experience with various Linux distros, but am happy to use another Unix FreeBSD and OpenSolaris seem to be the best choices for hosting ZFS OpenSolaris' hardware support is nowhere near as good as e.g. Ubuntu btrfs, while looking very good, doesn't seem ready for prime-time yet ZFS doesn't let you (easily?) add new discs to a RAID5 or RAID-Z reading around, it seems that ZFS is a bit short of tools for recovering lost data At the moment, I'm leaning towards running FreeNAS+ZFS, but I'm concerned about the requirement to be able to add new disc on a fairly regular basis to an existing RAID-Z. Can anyone provide some recommendations, or share experiences? Thanks in advance

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  • Setting up a home server - what to use? (ZFS vs btrfs, BSD vs Linux, misc other requirements)

    - by monch1962
    I need to get all our home content off individual machines and onto a central server. What I'd like to have is the metaphorical "server under the stairs". Stuff we need: expandable storage. I want to be able to add extra disc as we go along, with minimal maintenance required. Currently we've got about 3Tb of files we need to host, and that's likely to grow by another Tb every 6-12 months based on recent history. I need to be able to add additional disc with minimal pain needs to store all the media (i.e. photos, video, music) we have, and run services to serve the various devices we have in the house to playback (e.g. DAAP so we can play stuff through iTunes, ccxstream so we can play stuff over XBMC). DAAP and ccxstream are needed now, but we also need to support new standards as they emerge (so a closed-box solution isn't going to work) RAID 5, or something broadly equivalent (e.g. RAID-Z) BitTorrent client ssh, NFS, Samba access snapshot capability (as in ZFS), so we can snapshot individual file systems regularly and rollback when my kids delete their school assignments the day before they're due... ability to recover quickly from power outages (it's not unusual for us to have power outages that last longer than our UPS' batteries) FOSS software a modern distributed version control system running on the box, such as Mercurial Stuff I'd like to have on the server, but can live without: PVR capability, so I could record TV to the box Web server. We currently run a small Web server on a very old box, and I'd ideally like to turn the old box off and move the content to the new server just to save some electricity Nagios + mrtg I've been looking at using a EEE Box as the server, primarily because I can get them cheap and they don't consume much power. The choice of OS and file system is more difficult, from what I've found: I've got most experience with various Linux distros, but am happy to use another Unix FreeBSD and OpenSolaris seem to be the best choices for hosting ZFS OpenSolaris' hardware support is nowhere near as good as e.g. Ubuntu btrfs, while looking very good, doesn't seem ready for prime-time yet ZFS doesn't let you (easily?) add new discs to a RAID5 or RAID-Z reading around, it seems that ZFS is a bit short of tools for recovering lost data At the moment, I'm leaning towards running FreeNAS+ZFS, but I'm concerned about the requirement to be able to add new disc on a fairly regular basis to an existing RAID-Z. Can anyone provide some recommendations, or share experiences? Thanks in advance

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  • Setting up a home server - what to use? (ZFS vs btrfs, BSD vs Linux, misc other requirements)

    - by monch1962
    I need to get all our home content off individual machines and onto a central server. What I'd like to have is the metaphorical "server under the stairs". Stuff we need: expandable storage. I want to be able to add extra disc as we go along, with minimal maintenance required. Currently we've got about 3Tb of files we need to host, and that's likely to grow by another Tb every 6-12 months based on recent history. I need to be able to add additional disc with minimal pain needs to store all the media (i.e. photos, video, music) we have, and run services to serve the various devices we have in the house to playback (e.g. DAAP so we can play stuff through iTunes, ccxstream so we can play stuff over XBMC). DAAP and ccxstream are needed now, but we also need to support new standards as they emerge (so a closed-box solution isn't going to work) RAID 5, or something broadly equivalent (e.g. RAID-Z) BitTorrent client ssh, NFS, Samba access snapshot capability (as in ZFS), so we can snapshot individual file systems regularly and rollback when my kids delete their school assignments the day before they're due... ability to recover quickly from power outages (it's not unusual for us to have power outages that last longer than our UPS' batteries) FOSS software a modern distributed version control system running on the box, such as Mercurial Stuff I'd like to have on the server, but can live without: PVR capability, so I could record TV to the box Web server. We currently run a small Web server on a very old box, and I'd ideally like to turn the old box off and move the content to the new server just to save some electricity Nagios + mrtg I've been looking at using a EEE Box as the server, primarily because I can get them cheap and they don't consume much power. The choice of OS and file system is more difficult, from what I've found: I've got most experience with various Linux distros, but am happy to use another Unix FreeBSD and OpenSolaris seem to be the best choices for hosting ZFS OpenSolaris' hardware support is nowhere near as good as e.g. Ubuntu btrfs, while looking very good, doesn't seem ready for prime-time yet ZFS doesn't let you (easily?) add new discs to a RAID5 or RAID-Z reading around, it seems that ZFS is a bit short of tools for recovering lost data At the moment, I'm leaning towards running FreeNAS+ZFS, but I'm concerned about the requirement to be able to add new disc on a fairly regular basis to an existing RAID-Z. Can anyone provide some recommendations, or share experiences? Thanks in advance

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  • hadoop beginners question

    - by Omnipresent
    I've read some documentation about hadoop and seen the impressive results. I get the bigger picture but am finding it hard whether it would fit our setup. Question isnt programming related but I'm eager to get opinion of people who currently work with hadoop and how it would fit our setup: We use Oracle for backend Java (Struts2/Servlets/iBatis) for frontend Nightly we get data which needs to be summarized. this runs as a batch process (takes 5 hours) We are looking for a way to cut those 5 hours to a shorter time. Where would hadoop fit into this picture? Can we still continue to use Oracle even after hadoop?

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  • Proper NSArray initialization for ivar data in a method

    - by Joost Schuur
    I'm new to Objective-C and iPhone development and have been using Apress' Beginning iPhone 3 Programming book as my main guide for a few weeks now. In a few cases as part of a viewDidLoad: method, ivars like a breadTypes NSArray are initialized like below, with an intermediate array defined and then ultimately set to the actual array like this: NSArray *breadArray = [[NSArray alloc] initWithObjects:@"White", @"Whole Weat", @"Rye", @"Sourdough", @"Seven Grain", nil]; self.breadTypes = breadArray; [breadArray release]; Why is it done this way, instead of simply like this: self.breadTypes = [[NSArray alloc] initWithObjects:@"White", @"Whole Weat", @"Rye", @"Sourdough", @"Seven Grain", nil]; Both seem to work when I compile and run it. Is the 2nd method above not doing proper memory management? I assume initWithObjects: returns an array with a retain count of 1 and I eventually release breadTypes again in the dealloc: method, so that wraps things up nicely. I'm guessing 'self.breadTypes = ...' copies the data to the new array, which is why the original array can be safely released, correct?

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  • Advice needed from PHP/Cake PHP expert

    - by Hiro
    I'm very new to programming (besides SQL and databases), but I ultimately want to master Cake PHP for web development. Now, given how new I am, I'm rather lost as to how I get started. Down the road, I want to use MVC framework so that I help myself be disciplined in the way I build. However, I know basic knowledge of PHP and OOP PHP are required. So my question is this: what are the right steps to mastering Cake PHP? I don't want to skip critical phases of learning before learning to Cake PHP. At the same time, I don't want to spend more time than required learning PHP if I can learn it directly through Cake PHP knowledge. Any advice would be appreciated.

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  • XSLT: Is there a way to "inherit" canned functionality?

    - by Ian Boyd
    i am once again having to cobble together a bit of XSLT into order to turn generated XML into (rather than simply generating HTML). i'm having huge deja-vu this time again. i'm once again having to solve again basic problems, e.g.: how to convert characters into valid html entity references how to preserve whitespace/carriage returns when converting to html how to convert to HTML as opposed to xhtml how to convert dates from xml format into presentable format how to tear apart strings with substring This is all stuff that i've solved many times before. But every time i come back to XSLT i have to start from scratch, re-inventing the wheel every time. If it were a programming language i would have a library of canned functions and procedures i can call. i would have subroutines to perform the commonly repeated tasks. i would inherit from a base class that already implements the ugly boilerplate stuff. Is there any way in XSLT to grow, expand and improve the ecosystem with canned code?

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  • How to create windows form to display properly in all monitors?

    - by madhu bn
    I have created a windows form using (vs.net 2008 and vb.net as programming lanugage). Functionality part is working fine as expected. My issues is that, when i run my application in different machines, the form display is not proper accross the monitory screen. In some machines i noticed extra space on leftside of the container. In some other machine's it is vice versa. If you maximize or restore the form, the size varies. I tried to check the window form design on different machines using visual studio 2008, there also the form design looks differently. Please give me the solution to fix this issue. Thanks in advance.

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  • How to create windows form to display properly in all monitors?

    - by Madhu
    I have created a windows form using (vs.net 2008 and vb.net as programming lanugage). Functionality part is working fine as expected. My issues is that, when i run my application in different machines, the form display is not proper accross the monitory screen. In some machines i noticed extra space on leftside of the container. In some other machine's it is vice versa. If you maximize or restore the form, the size varies. I tried to check the window form design on different machines using visual studio 2008, there also the form design looks differently. Please give me the solution to fix this issue. Thanks in advance.

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  • iphone tableview multilevel

    - by Anonymous
    Hi, I 'm a iphone programming newbie. I m trying to implement an app with multi-level tableviews. The idea is if someone selects something on the first screen say then a new view opens(tableview) car make> list of models Honda > Acura, S2000,accord ... My challenge is to show the list of models in a new tableview & secondly change the size of hte list depending on the car selected. I have programmed so that when i select 'Honda' a new tableview opens. How do i populate data for the second table?? Any suggestions on how to proceed? thanks

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  • Is Steam for Mac effectively running as superuser?

    - by godDLL
    When you download the client it does not weigh too much, and seems to do very little. Inside the app bundle there is a script that—upon inspecting the environment and deciding you're not running Linux—launches the client, which downloads the full support environment and resources. For this to happen (all of this is saved inside the bundle, the app bundle gets updated in this process) Steam wants Universal Access for Assistive Devices, and your password. Cacheable resources, preferences (like keyboard shortcuts), support files (like game hardware requirement lookup tables) live inside the bundle, not in ~/Library/{Application Support|Preferences|Cache}; games' data get dumped into ~/Documents/Steam Content. I'd describe myself as a bit OCD (which really says a lot), and I wouldn't care that much still. I'd go comb this hairy mess and find out where stuff is, when and if I need to, even if it's in an unfamiliar place; that does not actually tick me off. Well, a little bit. What makes me concerned is the way Steam needs both Access for Assistive Devices, and my password to run. The former gives it the ability to talk very intimately with running apps and the underlying system; while the latter (admin account) could very well give it and it's publishers unrestricted access to all my software, hardware and data. With publishers like Rockstar using scene NOCD cracks to publish their games on Steam, I'm not so sure I'm OK with this. I'd like more games made available for the MacOS X and all the pretty machines that run it, but this arrangement does not seem very Mac-like to me. It looks like Valve is going around system security measures and best practices, foregoing sandboxing, code signing, relatively sane structured organization; all the things that would appeal to someone who's no fun at parties at all, and will die alone, in his long dead mother's basement… wait. Right. Anyway. Can we get some input on Steam for Mac security at the end-user machine, from someone who understands how Accessibility API works, whether games distributed on Steam can read and write outside the user homefolder, collect data from other running apps, or similar?

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  • C# Silverlight - XmlDictionary from Uri

    - by Robert White
    I've been developing a Silverlight application for a company's website and have encountered a problem. Up until now I have been programming this locally, now I need to publish the program onto the website; the issue is that FileStream can only access local files with elevated permissions. Here's a snippet of code: using (FileStream fileStream = new FileStream(@"E:\Users\LUPUS\Documents\Visual Studio 2010\Projects\Lycaon5\Lycaon5\acids.xdb", FileMode.Open)) { using (XmlDictionaryReader reader = XmlDictionaryReader.CreateTextReader(fileStream, XmlDictionaryReaderQuotas.Max)) { //Read the XML file out. } } Without changing anything to do with XmlDictionaryReader reader - How could I go about reading the files from a relative Uri? Many Thanks, Rob. P.s. Apologies for the lack of formatting, me cave man, me don't know how.

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  • how to get an SDP record for bluetooth service??

    - by user302798
    Hi I'm new to both winsock and bluetooth programming. I need to develop a bluetooth service to run on a pc. Looking at the MSDN library they say to use WSASetService(http://msdn.microsoft.com/en-us/library/aa362921%28VS.85%29.aspx) function to publish a service. The problem is that the WSAQUERYSET(http://msdn.microsoft.com/en-us/library/aa362920%28VS.85%29.aspx) structure, that has to be passed to WSASetService, needs a binary SDP record and i don't know how to get it. In the Windows embedded section of the MSDN library they describe a procedure to obtain an SDP record using Bthnscreate. I installed Windows CE 6 to use this tool but i can't find it in the install directory nor in the entire system. How can i get an SDP record? Thanks!

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  • How to access parent Iframe from javascript

    - by José Leal
    Well, I have an IFrame, which calls a same domain page. My problem is that I want to access some information from this parent Iframe from this called page (from javascript). How can I access this Iframe? Details: There are severals Iframes just like this one, that can have the same page loaded, because I am programming a windows environment. I intend to close this Iframe, that's why I need to know which I should close from inside him. I have an array keeping references to these Iframes EDIT: There iframes are generated dynamically

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  • Ios Parse Login

    - by user3806600
    I am programming an IOS app that will use parse to login a user. Using storyboard I have the login button connected to another view controller with the push segue. Whether the username and password are correct the button selection always goes to the new view controller. I might be doing this all wrong. Any help is appreciated. Here is my code: - (IBAction)signIn:(id)sender { [PFUser logInWithUsernameInBackground:self.emailField.text password:self.passwordField.text block:^(PFUser *user, NSError *error) { if (!error) { [self performSegueWithIdentifier:@"signIn" sender:nil]; } else { // The login failed. Check error to see why. } }]; }

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  • Separating arguments to a function, in locales with comma as decimal marker

    - by Chris Pousset
    In locales, e.g. French, with comma as decimal indicator (where "5,2" means five and two-tenths), how do users separate function arguments from each other? For example, in many programming/scripting languages, I could specify MAX(1.5, X) in a EN-US locale. How do you avoid the ambiguity between the comma as decimal indicator, and as argument separator? In particular, I'm interested in how software that's perceived as user-friendly in the foreign locale does it. Obviously, it's a no-brainer to say, "thou shalt use decimal POINTs", but that's not particularly "friendly".

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  • Can I use Win32 FreeType without the .dll file?

    - by Khatharr
    Hello. I'm teaching myself OpenGL and I'm implementing ttf text rendering using FreeType 2. I downloaded the library from http://gnuwin32.sourceforge.net/packages/freetype.htm and after a couple of minor issues I got it running properly. The thing that's bothering me is that I have to place a copy of freetype6.dll in the directory with my executable in order for the thing to run. I generally try to avoid a bunch of unnecessary dll files floating around. I'm sort of new to windows programming, but from what I understand most libraries can be built to run fully from a lib rather than requiring a dll at runtime. Looking through the documentation from FT is making my brain melt, so I thought I would ask here to see if there were any devs that have worked with FT before and if so, do they know how to build the library such that no dll is required at runtime. Thank you in advance for any advice or support.

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  • (iPhone SDK) How to link instance variables to a specific UILabel

    - by Timbo
    I'm using the iPhone SDK to build a simple application. I've created a brand new class which has a single variable. I need to make 5 instances of that class, which I have no trouble doing. I can create those instances and also set the variables without issue. What i do need to know is this: How do I link each of the 5 different instances of the variable to different and specific UILabels? Would I be better to create a method that dynamically creates and positions the labels? Thanks for your help in advance, I'm now to this iphone programming thing. I'm serious about learning fast though so I have posted a bounty on this question here : http://www.askearn.com/Responses.aspx?QuestionID=6542613f-7be8-4bb3-a950-aac218d47711

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  • Edit Distance in Python

    - by Alice
    I'm programming a spellcheck program in Python. I have a list of valid words (the dictionary) and I need to output a list of words from this dictionary that have an edit distance of 2 from a given invalid word. I know I need to start by generating a list with an edit distance of one from the invalid word(and then run that again on all the generated words). I have three methods, inserts(...), deletions(...) and changes(...) that should output a list of words with an edit distance of 1, where inserts outputs all valid words with one more letter than the given word, deletions outputs all valid words with one less letter, and changes outputs all valid words with one different letter. I've checked a bunch of places but I can't seem to find an algorithm that describes this process. All the ideas I've come up with involve looping through the dictionary list multiple times, which would be extremely time consuming. If anyone could offer some insight, I'd be extremely grateful. Thanks!

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  • VBA Excel macro: use Range to act on a different worksheet

    - by David Oneill
    I am very much a beginner when it comes to VBA programming. I have a Macro that hides or shows columns based on the value in one cell: Sub HideColumnsMacro() Range("b8:o8").EntireColumn.Hidden = False v1 = Range("b2").Value + 1 If v1 < 12 Then With Range("b8") Range(.Offset(0,v1), .Offset(0, 12)).EntireColumn.Hidden = True End With End If End Sub I want to be able to get this same functionality when I change a cell on a different sheet. Is there a way I can tell this Macro to act on this sheet, when it is run from a different one?

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  • Groovy 1.7 changes "final"?

    - by Aaron L. Carlow
    Just started learning Groovy, got the PragProg book "Programming Groovy" and had a problem compiling one of the sample scripts: class GCar2 { final miles = 0 def getMiles() { println "getMiles called" miles } def drive(dist) { if (dist > 0) { miles += dist } } } def car = new GCar2() println "Miles: $car.miles" println 'Driving' car.drive(10) println "Miles: $car.miles" try { print 'Can I see the miles? ' car.miles = 12 } catch (groovy.lang.ReadOnlyPropertyException ex) { println ex.message GroovyCar2.groovy: 20: cannnot access final field or property outside of constructor. @ line 20, column 35. def drive(dist) { if (dist > 0) miles += dist } ^ Groovy versions prior to 1.7 do not give an error. I looked through whatever documentation I could find and did not see the issue discussed. What is going on here? Aaron

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  • Do you know any code sharing sites?

    - by jasondavis
    I am always looking to organize and make my resource bookmarks better and easiar to access when I need them. 1 thing I really like is code sharing sites, they let you enter in code and then give you a special link to give a friend or a user on this site even to show then code, This is a very useful tool I believe. So below is my list of code sharing sites, there is 4 on the list and they all have unique features. Some have syntax highlighting for multiple languages, some allow you to save your code as private and only share with the people you give the link to, and some even run the run and output any possible errors. Do you know of any sites like this? if you know of any sites like this for programming code please post it here. http://pastie.org/ http://codepad.org/ http://pastebin.me/ http://jsbin.com/ allows you to auto-insert a javascript library like jquery and test live js code

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  • Recieving server broadcast on mobile in real time

    - by Manjoor
    I have to write a simple mobile application that is able to recieve broadcast from a server, connected using GPRS, over a secure SSL connection. The amount of data mobile need to recieve is very small (about 100 character string for a single broadcast and maximum 10 broadcast per minute) I need to display it on screen and generate a alert sound (and vibrate the device). Client need not to send anything back to server. (ofcourse at the time of intialization the client app need to send some data for authorization) The target mobile plateform is symbion S60 and Blackberry. How can i do this? What tools, SDK and Third party framework (if needed) i should use? I am familier with java and network programming but not for mobile device.

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