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• Android/ iOS how to determine small changes in distance using sensors?

  - by Tom

  I have been doing a bit of research, but I cannot seem to find a way to determine small distances (centimeters and meters) using the sensors in Android or iOS devices. Bluetooth appears too inaccurate and require more than one device, GPS only works over larger variations in distance, and small variations in rotation seem to make using the accelerometer nearly impossible. Is there a method that I am unaware of that would allow me to do such a thing? I am familiar with Calculus, so using Integrals to determine distance based on changes in time and velocity/ acceleration is not a problem for me, I just do not know how to determine those things. Thank you.

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• Access static constant variable from multiple threads in C

  - by user325519

  I have some experience with multithread programming under Linux (C/C++ & POSIX threads), however most obvious cases are sometimes very complicated. I have several static constant variables (global and function local) in my code, can I access them simultaneously from multiple threads without using mutexes? Because I don't modify them it should be ok, but it's always better to ask. I have to do heavy speed optimization, so even as fast operations as mutex lock/unlock are quite expensive for me, especially because my application is going to access these variables form long loops.

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• How can Domain driven design be combined with aspect oriented programming?

  - by anthares

  I'm doing research and one point I want to cover is "What is the relationship between Domain-driven Design and Aspect oriented programming?" I know that a main principle in DDD is separation of concerns and I understand that. What I'm not really certain is, whether aspects in AOP acts like "sub domains" in our domain in DDD. Are these two concepts, basically the same thing. I mean, If I develop an application following AOP and DDD, at the end of the day will it be true that "a sub domain" == "an aspect". I will also appreciate any other opinions what is the common between AOP and DDD.

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• How to implement a set ?

  - by nomemory

  I want to implement a Set in C. Is it OK to use a linked list, when creating the SET, or should I use another approach ? How do you usually implement your own set (if needed). NOTE: If I use the Linked List approach, I will probably have the following complexities for my operations: init : O(1); destroy: O(n); insert: O(n); remove: O(n); union: O(n*m); intersection: O(n*m); difference: O(n*m); ismember: O(n); issubset: O(n*m); setisequal: O(n*m); O(n*m) seems may be a little to big especially for huge data... Is there a way to implement my Set more efficient ?

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• Is there a way to set a DLL to always follow CultureInfo.InvariantCulture by default, if not specifi

  - by JL

  I have a lot of code in a class library that does not specify CultureInfo.InvariantCulture. For example in toString operations, toBool, toInt, etc. Is there a way I can get set a property for the class library to always execute using CultureInfo.InvariantCulture, even if it is not explicitly specified everywhere in the code? Sort of like a global switch? It is not only messy to have to explicitly type it everytime, it makes my code less readable, and is a royal pain for example: if (Convert.ToInt16(task.RetryCount, CultureInfo.InvariantCulture) < Convert.ToInt16(ConfigurationManager.AppSettings["TasksMaxRetry"], CultureInfo.InvariantCulture))

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• How to integrate Python scripting in my Android App (like SL4A)

  - by Seraphim's host

  I need to add scripting layer to my android App. So I can remotely prepare a script that my app download form a web service and execute on the user device. I found a interesting project called Scripting Layer for Android (SL4A) here: http://code.google.com/p/android-scripting/ I'm not sure I can execute Python script without installing the PythonForAndroid_r4.apk first. I can't force my customer to install that application! So my question is, can the SL4A layer be integrated in my app without the need to install other apk? I need to execute actions like update data in the DB, create/read/delete a file on the sd card... Not so complex but I see SL4A can do a lot of things like these. Other scripting libraries? EDIT: Found also MVEL: http://mvel.codehaus.org/ but I think it needs to be integrated to execute complex operations like accessing a DB...

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• Background image JFrame with content

  - by Petr Safar

  I have a JFrame with BorderLayout, there are panels on all sides (North, East ,...). In the panels there are labels and buttons mostly. Now I want the frame to have a background image, some research told me that i had to change the content pane of my frame. When I try this however, the content gets put in the background and isn't visible. Also, I don't know how to resize the image if the frame is resized. Is there an easy fix for this or will I have to rework most of my code?

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• find all occurrences of comparison with == in visual studio

  - by Emiswelt

  Hi there I made the mistake of using == for comparing IP addresses instead of using the equals() method of the IPAddress class in C#, which will result in the comparison of references instead of values. Since the solution I am currently working on is very large for a one-man project ( 100.000 lines of source code), I am very sure that I still have some of these wrong statements in my code. Is there any possibility to tell Visual Studio to find all occurrences of == operations on a specific class for me, so that I can find and clean up the bugged comparisons? with best regards, emi

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• What can cause reset connection when running PHP script?

  - by marcin_koss

  I've developed a web application with CodeIgniter that works perfectly on my local machines (one with windows and one with Linux). When I moved it to my hosting server, connection gets reset when running one particular PHP script that does a few MySQL queries and some operations on arrays. The data I'm querying is small, just a few tables with up to 25 records. Firefox returns "The connection was reset" after maybe 2-3 seconds. I checked the servers error logs but there was nothing there. Unfortunately I don't have access to Apache error logs. What can cause this behavior?

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• hadoop - large database query

  - by Mastergeek

  Situation: I have a Postgres DB that contains a table with several million rows and I'm trying to query all of those rows for a MapReduce job. From the research I've done on DBInputFormat, Hadoop might try and use the same query again for a new mapper and since these queries take a considerable amount of time I'd like to prevent this in one of two ways that I've thought up: 1) Limit the job to only run 1 mapper that queries the whole table and call it good. or 2) Somehow incorporate an offset in the query so that if Hadoop does try to use a new mapper it won't grab the same stuff. I feel like option (1) seems more promising, but I don't know if such a configuration is possible. Option(2) sounds nice in theory but I have no idea how I would keep track of the mappers being made and if it is at all possible to detect that and reconfigure. Help is appreciated and I'm namely looking for a way to pull all of the DB table data and not have several of the same query running because that would be a waste of time.

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• Mobile Aps that will detect/accept incoming SMS msg?

  - by user848682

  Im working on my thesis and I need some help. My thesis is like some "automated replying system for mobile apps". My questions: 1st: How to make an application that can detect incoming message? ( even some sample documentation will do, Ill d own my research ) 2nd: Is there any tool I need to achieve this? 3rd: What language is usally used for mobile application programming? 4th: Is it possible to achieve this? Thanks in Advance : ) Sorry I dont have any knowledge in mobile aps programming.

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• Capture IP packets on Dialup connection - Windows 7

  - by Assaf Levy

  Our product utilizes (the wonderful) Winpcap to capture ip packets from all devices with an IP address and analyze them in real time. Unfortunately, we discovered that it does NOT capture any packets on dialup (e.g. PPP) connections on Windows 7, and that there are no near-term plans for enabling this (1). So we need something else. Microsoft Network Monitor and Windows Packet Filter are two options that surfaced during a bit of googling, but before delving into research I wanted to ask the experienced: what are out options, given the following requirements: Capture all in/outbound IP packets on the machine. Complete background processing - no UI should be involved. Support Windows Vista / 7. Performance (user should not feel the difference). Thanks in advance.

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• More Poll() ?'s

  - by ultifinitus

  Back again! I've been doing some async socket programming with select() on windows,and it's been working quite well. However it's only scalable up to 1024 clients.Poll() is the way to get around that limitation, and I know it works on both linux and unix. But it doesn't work with a windows system correct? I read about WsaPoll(), does it have the exact same functionality? What libraries would I have to link to in order to use it? Can I increase the socket number safely in windows with FD_SETSIZE? My end program will be on a linux server. However I am testing on a windows system right now. Should I just swap my test machine over to a linux box? (probably going to anyway) Otherwise what would you recommend to use with windows? (sorry for all of the questions, I am doing research on my own, I promise =D)

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• Share data between local service and the hosting activity

  - by Moshik

  Hi, i need to share data between a local service and his hosting activity, i`am using sendBroadcast in order to send data to the hosting activity from the service, but if i want to send data back to the service from the hosting activity? so i though to create static method on the service, and call from the activity, and through it send the parameter, but then i cant do operations like toast inside that static method(which is inside the service).. coz you cant use "myclass.this" inside a static method, i guess there r more limits.. mybe another solution? mybe there is a proper way for this task? thanks, moshik.

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• Speedup C++ code

  - by Werner

  Hi, I am writing a C++ number crunching application, where the bottleneck is a function that has to calculate for double: template<class T> inline T sqr(const T& x){return x*x;} and another one that calculates Base dist2(const Point& p) const { return sqr(x-p.x) + sqr(y-p.y) + sqr(z-p.z); } These operations take 80% of the computation time. I wonder if you can suggest approaches to make it faster, even if there is some sort of accuracy loss Thanks

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• How to safely remove a USB drive on Windows CE 5.0?

  - by Radu C

  Until today, I assumed that Windows CE was writing everything to disk and I wouldn't end up with a broken FAT16 when I removed the USB stick. Today, I was proven wrong. I use a USB stick to test things on a WinCE 5.0 device. I don't write anything from the app or WinCE to the stick. I just execute my app, and my app reads its settings and pictures from the stick. Today, just this order of operations broke my stick filesystem (and I have to fix it). Is there a way to tell WinCE 5.0 to unmount the stick before I remove it? It sees it as a "Hard Drive", and the tap-and-hold menu has nothing along the lines of "safely remove drive". I'm happy with both code to do this operation and some trick that I didn't find in Windows CE yet. Thank you.

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• Rails modeling for a user

  - by Trevor Hartman

  When building a rails app that allows a User to login and create data, is it best to setup a belongs_to :user association on every single model? For example, let's say a user can create Favorites, Colors and Tags. And let's say Favorites has_many :tags and Colors also has_many :tags. Is it still important for Tags to belong_to :user assuming the User is the only person who has authority to edit those tags? And a similar question along the same lines: When updating data in FavoritesController, I've come to the conclusion that you perform CRUD operations by always doing something like User.favorites.find(params[:id].update_attributes(param[:favorite]) so that they can definitely only update models that belong to them. Right?

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• Replace String pattern in Java

  - by Hirantha

  I have the following string "value=\"\\d{4}((((0[1-9])|(1[0-2]))((0[1-9])|([12]\\d)|(3[01]))?)?|(\\-(((0[1-9])|(1[0-2]))(\\-((0[1-9])|([12]\\d)|(3[01])))?)?)?)d{4}" There I want to replace all the occurrences of "{" with NCHAR(0x7B) "}" with NCHAR(0x7D). An the content in-between "{ }" should remain unchanged: Ex: \\d{4} after replacing -> NCHAR(0x7B) 4 NCHAR(0x7D). Is there a way to do this using Regular Expressions in Java?. Anyway, this can be done processing the whole string using string operations.

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• Detecting metadata-only read requests in windows filesystem

  - by HyLian

  Hello, I'm developing a kind of filesystem driver. All of read requests that windows makes to my filesystem goes by the driver implementation. I would like to distinguish between "normal" read requests and those who want to get only the metadata from the file. ( Windows reads first 4K of the file and then stop reading ). Does Windows mark this metadata reads in some way? It would be very useful in order to treat that two kind of operations in a different way. In a typical CreateFile call, we have AccessMode, ShareMode, CreationDisposition and FlagsAndAttributes parameters ( being DWORD ), i'm not sure if it's possible to extract some clue of the operation requested. Thanks for reading :)

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• Shortest distance between points on a toroidally wrapped (x- and y- wrapping) map?

  - by mstksg

  I have a toroidal-ish Euclidean-ish map. That is the surface is a flat, Euclidean rectangle, but when a point moves to the right boundary, it will appear at the left boundary (at the same y value), given by x_new = x_old % width Basically, points are plotted based on: (x_new, y_new) = ( x_old % width, y_old % height) Think Pac Man -- walking off one edge of the screen will make you appear on the opposite edge. What's the best way to calculate the shortest distance between two points? The typical implementation suggests a large distance for points on opposite corners of the map, when in reality, the real wrapped distance is very close. The best way I can think of is calculating Classical Delta X and Wrapped Delta X, and Classical Delta Y and Wrapped Delta Y, and using the lower of each pair in the Sqrt(x^2+y^2) distance formula. But that would involve many checks, calculations, operations -- some that I feel might be unnecessary. Is there a better way?

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• Controlled hyperlink hijaxing

  - by Izmoto

  I am working on a web application. I have a data grid with a 'commands' column that has hyperlinks for some common CRUD operations (Edit, Delete, etc). When a user clicks on say the Edit hyperlink, I retrieve the unique identifier for the data grid row and load a modal form dialog (i am using jQuery UI) so the user is able to edit the row data and subsequently close the modal form dialog at which point I refresh the page. Now, before the page is done refreshing, there's a chance that a user might click on the edit link again, and whenever that happens, 'hijaxing' fails. My question is how can i check that if a user clicks on a hyperlink and the page is refreshing, i delay until it is done refreshing, then i allow the 'hijax' to kick in.

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• Can I find out what WCF methods are supported on the endpoint before calling it?

  - by alord1689

  I have a versioning issue with a WCF service contract in which one of the many endpoints which are called for the operation is missing one method from the contract. My question is, how can I make sure the command is available on the client before attempting to call it? I tried: foreach (var od in proxy.Endpoint.Contract.Operations) { if (od.Name == "MyMethodName") { hasMethod = true; break; } } Unfortunately, this is using the contract from the calling app and does not actually describe the implementations on the endpoint itself. As a result, it returns true even though the endpoint has failed to implement the command.

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• Magento: setup both APC and memcached

  - by snh_nl

  Magento: setup both APC and memcached Hi, our hosting party installed both APC and memcached. How do I configure both correctly - so that they dont start caching each other for example. any ideas? I would like the following: opcode for php, so APC is primary cache cache /var/session and /var/cache cache / speedup database requests And we have fullpage cache now, how do we relate this My question - What settings do I need? It is not clear how these two work together ... I did some research and found this: http://www.coeusblue.com/blog/48-magento/65-magento-caching http://magebase.com/magento-tutorials/speeding-up-magento-with-apc-or-memcached/

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• sortable + draggable demo - how to get access to dropped item?

  - by user246114

  Hi, I have a sortable list. When a new item is dropped into the list (from a draggable), I'd like to get access to it to perform some operations on it. This is what I have: $("#mySortableList").sortable({ receive: function(event, ui) { alert("this is the dropped item: " + ui.item.toString()); } }).disableSelection(); so "ui.item" is the element that was dropped, but it's not the duplicated item that will now be part of my list. How do I get access to the new item that was dropped? I am using the exact demo from the jquery-ui site here: http://jqueryui.com/demos/draggable/#sortable Thanks

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• Sql Server 2000 Stored Procedure Prevents Parallelism or something?

  - by user187305

  I have a huge disgusting stored procedure that wasn't slow a couple months ago, but now is. I barely know what this thing does and I am in no way interested in rewriting it. I do know that if I take the body of the stored procedure and then declare/set the values of the parameters and run it in query analyzer that it runs more than 20x faster. From the internet, I've read that this is probably due to a bad cached query plan. So, I've tried running the sp with "WITH RECOMPILE" after the EXEC and I've also tried putting the "WITH RECOMPLE" inside the sp, but neither of those helped even a little bit. When I look at the execution plan of the sp vs the query, the biggest difference is that the sp has "Parallelism" operations all over the place and the query doesn't have any. Can this be the cause of the difference in speeds? Thank you, any ideas would be great... I'm stuck.

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