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  • Special simple random number generator

    - by psihodelia
    How to create a function, which on every call generates a random integer number? This number must be most random as possible (according to uniform distribution). It is only allowed to use one static variable and at most 3 elementary steps, where each step consists of only one basic arithmetic operation of arity 1 or 2. Example: int myrandom(void){ static int x; x = some_step1; x = some_step2; x = some_step3; return x; } Basic arithmetic operations are +,-,%,and, not, xor, or, left shift, right shift, multiplication and division. Of course, no rand(), random() or similar staff is allowed.

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  • How to Parse 'Mathy' Stuff...

    - by Rob P.
    Please forgive my title, I really don't know how to phrase it better. This isn't a school assignment or anything, but I realize it's a mostly academic question. But, what I've been struggling to do is parse 'math' text and come up with an answer. For Example - I can figure out how to parse '5 + 5' or '3 * 5' - but I fail when I try to correctly chain operations together. (5 + 5) * 3 It's mostly just bugging me that I can't figure it out. If anyone can point me in a direction, I'd really appreciate it.

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  • Event(s) for opening the workbook AND worksheets

    - by KeyMs92
    I'm looking for an elegant solution to trigger an event for opening the workbook as well as opening different worksheets. I don't need seperate operations for each worksheet: they all trigger the same method. I know I can use the events Workbook_Activate / Workbook_Open and Workbook_SheetActivate at the same time but I don't know if this is 'the official way' to do it. Perhaps there's a way to do this with one event. I was also wondering if it is relevant in this matter where I put the code. I now have all the code inside "ThisWorkbook" and not in a "Module"...

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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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  • How to optimize indexing of large number of DB records using Zend_Lucene and Zend_Paginator

    - by jdichev
    So I have this cron script that is deployed and ran using Cron on a host and indexes all the records in a database table - the index is later used both for the front end of the site and the backed operations as well. After the operation, the index is about 3-4 MB. The problem is it takes a lot of resources (CPU: 30+ and a good chunk of memory) and slows the machine down. My question is about how to optimize the operation described below: First there is a select query built using the Zend Framework API, this query is then passed to a Paginator factory that returns a paginator which I am using to balance the current number of items being indexed and not iterate over too much items. The script is iterating over the current items in the paginator object using a foreach loop until reaching the end and then it starts from the beginning after getting items for the next page. I am suspecting this overhead is caused by the Zend_Lucene but no idea how this could be improved.

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  • What types of conditions can be used for conditional compilation in C++?

    - by user1002288
    This is an exam question for C++: Which of the following statements accurately describe the condition that can be used for conditional compilation in C++? A. The condition can depend on the value of environment variables. B. The condition can depend on the value of any const variables. C. The condition can depend on the value of program variables. D. The condition can use the sizeof() operator to make decision about compiler-dependent operations based on the size of standard data type. E. The condition must evaluate to either a 0 or 1 during preprocessing. I think the answer is E. Is this correct?

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  • C# eval equivalent?

    - by Adhip Gupta
    I can do an eval("something()"); to execute the code dynamically in JavaScript. Is there a way for me to do the same thing in C#? What I am exactly trying to do is that I have an integer variable (say i) and I have multiple properties by the names: "Property1","Property2","Property3" etc. Now, I want to perform some operations on the " Propertyi " property depending on the value of i. This is really simple with Javascript. Is there any way to do this with C#? Edit: Oh, and I am using C# 2.0

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  • Do I need to syncronize thread access to an int

    - by Martin Harris
    I've just written a method that is called by multiple threads simultaneously and I need to keep track of when all the threads have completed, the code uses this pattern: private void RunReport() { _reportsRunning++; try { //code to run the report } finally { _reportsRunning--; } } This is the only place within the code that _reportsRunning's value is changed, and the method takes about a second to run. Occasionally when I have more than six or so threads running reports together the final result for _reportsRunning can get down to -1, if I wrap the calls to _runningReports++ and _runningReports-- in a lock then the behaviour appears to be correct and consistant. So, to the question: When I was learning multithreading in C++ I was taught that you didn't need to synchronize calls to increment and decrement operations because they were always one assembly instruction and therefore it was impossible for the thread to be switched out mid-call. Was I taught correctly, and if so how come that doesn't hold true for C#?

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  • Cross-referencing UML models in VS 2010

    - by cheaster
    I am just starting to explore/use the UML modeling support in Visual Studio 2010 Umltimate. I have created two model projects within a single solution. Let's call them Model A and Model B. I have some data types (classes) defined in Model B. I want to use them as return types for operations in Model A. However, I cannot figure out how to make the types defined in Model B show up in Model A when attempting to set return type on an operation. Any help/suggestions would be greatly appreciated! Thanks!

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  • How do I determine darker or lighter color variant of a given color?

    - by Nidonocu
    Given a source color of any hue by the system or user, I'd like a simple algorithm I can use to work out a lighter or darker variants of the selected color. Similar to effects used on Windows Live Messenger for styling the user interface. Language is C# with .net 3.5. Responding to comment: Color format is (Alpha)RGB. With values as bytes or floats. Marking answer: For the context of my use (a few simple UI effects), the answer I'm marking as accepted is actually the most simple for this context. However, I've given up votes to the more complex and accurate answers too. Anyone doing more advanced color operations and finding this thread in future should definitely check those out. Thanks SO. :)

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  • Are spinlocks a good choice for a memory allocator?

    - by dsimcha
    I've suggested to the maintainers of the D programming language runtime a few times that the memory allocator/garbage collector should use spinlocks instead of regular OS critical sections. This hasn't really caught on. Here are the reasons I think spinlocks would be better: At least in synthetic benchmarks that I did, it's several times faster than OS critical sections when there's contention for the memory allocator/GC lock. Edit: Empirically, using spinlocks didn't even have measurable overhead in a single-core environment, probably because locks need to be held for such a short period of time in a memory allocator. Memory allocations and similar operations usually take a small fraction of a timeslice, and even a small fraction of the time a context switch takes, making it silly to context switch in the case of contention. A garbage collection in the implementation in question stops the world anyhow. There won't be any spinning during a collection. Are there any good reasons not to use spinlocks in a memory allocator/garbage collector implementation?

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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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  • i need help to designe code in c++

    - by user344987
    ) Design and implement a Graph data structure. Use adjacency matrix to implement the unweighted graph edges. The Graph must support the following operations: 1.Constructor 2.Destructor 3.Copy constructor 4.A function to add an edge between two nodes in the graph 5.A display function that outputs all the edges of the graph 6.A function edge that accepts two nodes, the function returns true if there is an edge between the passed nodes, and returns false otherwise. B.(100 points) Depth first search and Breadth first search functions. C.(100 points) A function to output a spanning tree of the graph, use any algorithm you find appropriate, also, make the necessary changes on the data structure in A to implement your algorithm.

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  • func_get_args detect context

    - by Steve
    I have a script where it accepts a varying number of arguments. I want to use func_get_args to perform operations on said arguments. If I have one function like this: function Something() { foreach(func_get_args($this) as $functions) { // Do something } // Return.. } I want to be able to call this function in, for example, another function to add/save entries. The add/save function would have arguments 'title', 'description' etc.. I basically want to know if there is a way to detect the context of a function call. Can I pass something to func_get_args that will let it know that its called in a certain function? So if I do: function Save($title, $desc) { $vars = $this->Something(); } I want $vars to contain $title and $desc after modifying them.

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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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  • 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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  • 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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  • How online-game clients are able to exchange data through internet so fast?

    - by Kirzilla
    Hello, Let's imagine really simple game... We have a labirinth and two players trying to find out exit in real time through internet. On every move game client should send player's coordinates to server and accept current coordinates of another client. How is it possible to make this exchange so fast (as all modern games do). Ok, we can use memcache or similar technology to reduce data mining operations on server side. We can also use fastest webserver etc., but we still will have problems with timings. So, the questions are... What protocol game clients are usually using for exchanging information with server? What server technologies are coming to solve this problem? What algorithms are applied for fighting with delays during game etc. PS: Sorry for my English and I hope that my question is clear. Thank you.

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  • finding character in string C language

    - by iSight
    Hi, I am searching a character at first occurence in string using the following code. But, it is taking some time when the character is too long or the character that i am searching is at far extend, which makes delay in other operations. How could i tackle with this problem. The code is below here. Note: attrPtr is a char* which holds a reference to a string containing '"' character at far extend. int position = 0; char qolon = '"';//character to search while (*(attrPtr + position++) != qolon); char* attrValue = NULL; attrValue = (char*)malloc(position * sizeof(char)); strncpy(attrValue, attrPtr, position-1);

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  • In Selenium IDE, can I store an element to use in subsequent asserts?

    - by Colin Fine
    I've just started using Selenium-IDE (not looked at selenium-RC yet: if somebody tells me that that is the answer to my question I'll look at it) One of the operations I'm testing generates some output in a table in the next HTML page, but the order of the rows is not predictable. I can obviously use 'assertTextPresent', but I want to do a bit more, and check that various bits of text are in the same row. What I would like to be able to do is to identify a tr by some content, and then use that tr in subsequent asserts; something like storeExpression //table[@id='TABLE_6']/td[.='case_1']/.. row assertText ${row} 'Some text' assertText ${row} 'Some other text' to check that 'Some text' and 'Some other text' occur in the same table row as 'case_1'. I haven't got this to work so far, and I'm not sure whether it is possible, or what syntax to use if it is. Has anybody managed to do this?

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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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  • Speed of interpolation algorithms, C# and C++ working together.

    - by Kaminari
    Hello. I need fast implementation of popular interpolation algorithms. I figured it out that C# in such simple algorithms will be much slower than C++ so i think of writing some native code and using it in my C# GUI. First of all i run some tests and few operations on 1024x1024x3 matrix took 32ms in C# and 4ms in C++ and that's what i basicly need. Interpolation however is not a good word because i need them only for downscaling. But the question is: Will it be faster than C# methods in Drawing2D Image outputImage = new Bitmap(destWidth, destHeight, PixelFormat.Format24bppRgb); Graphics grPhoto = Graphics.FromImage(outputImage); grPhoto.InterpolationMode = InterpolationMode.*; //all of them grPhoto.DrawImage(bmp, new Rectangle(0, 0, destWidth, destHeight), Rectangle(0, 0, sourceWidth, sourceHeight), GraphicsUnit.Pixel); grPhoto.Dispose(); Some of these method run in 20ms and some in 80. Is there a way to do it faster?

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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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  • When is a program limited by the memory bandwidth?

    - by hanno
    I want to know if a program that I am using and which requires a lot of memory is limited by the memory bandwidth. When do you expect this to happen? Did it ever happen to you in a real life scenario? I found several articles discussing this issue, including http://www.cs.virginia.edu/~mccalpin/papers/bandwidth/node12.html http://www.cs.virginia.edu/~mccalpin/papers/bandwidth/node13.html http://ispass.org/ucas5/session2_3_ibm.pdf The first link is a bit old, but suggests that you need to perform less than about 1-40 floating point operations per floating point variable in order to see this effect (correct me if I'm wrong). How can I measure the memory bandwidth that a given program is using and how do I measure the (peak) bandwidth that my system can offer? I don't want to discuss any complicated cache issues here. I'm only interested in the communication between the CPU and the memory.

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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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