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  • analysis Big Oh notation psuedocode

    - by tesshu
    I'm having trouble getting my head around algorithm analysis. I seem to be okay identifying linear or squared algorithms but am totally lost with nlogn or logn algorithms, these seem to stem mainly from while loops? Heres an example I was looking at: Algorithm Calculate(A,n) Input: Array A of size n t?0 for i?0 to n-1 do if A[i] is an odd number then Q.enqueue(A[i]) else while Q is not empty do t?t+Q.dequeue() while Q is not empty do t?t+Q.dequeue() return t My best guess is the for loop is executed n times, its nested while loop q times making NQ and the final while loop also Q times resulting in O(NQ +Q) which is linear? I am probably totally wrong. Any help would be much appreciated. thanks

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  • Query Returning value as 0

    - by NIMISH DESHPANDE
    I am trying to execute following PL/SQL script in SQL Developer. The loop should return count of nulls but somehow everytime it is returning 0. set serveroutput on DECLARE --v_count number; v_count_null number; BEGIN execute immediate 'select count(*) from SP_MOSAIX' into v_count; FOR i in (select column_name from all_tab_COLUMNS where table_name = 'SP_MOSAIX') LOOP select count(*) into v_count_null from SP_MOSAIX where i.column_name IS NULL ; dbms_output.put_line(v_count_null); END LOOP; END; So when I run this, following output is what i get: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 But if I manually execute the query subsituting column_name I get the result. select count(*) into v_count_null from SP_MOSAIX where i.column_name IS NULL; Can anybody help on this?

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  • Java anonymous class efficiency implications

    - by Po
    Is there any difference in efficiency (e.g. execution time, code size, etc.) between these two ways of doing things? Below are contrived examples that create objects and do nothing, but my actual scenarios may be creating new Threads, Listeners, etc. Assume the following pieces of code happen in a loop so that it might make a difference. Using anonymous objects: void doSomething() { for (/* Assume some loop */) { final Object obj1, obj2; // some free variables IWorker anonymousWorker = new IWorker() { doWork() { // do things that refer to obj1 and obj2 } }; } } Defining a class first: void doSomething() { for (/* Assume some loop */) { Object obj1, obj2; IWorker worker = new Worker(obj1, obj2); } } static class Worker implements IWorker { private Object obj1, obj2; public CustomObject(Object obj1, Object obj2) {/* blah blah */} @Override public void doWork() {} }; Thank you :)

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  • Joining different models in Django

    - by Andrew Roberts
    Let's say I have this data model: class Workflow(models.Model): ... class Command(models.Model): workflow = models.ForeignKey(Workflow) ... class Job(models.Model): command = models.ForeignKey(Command) ... Suppose somewhere I want to loop through all the Workflow objects, and for each workflow I want to loop through its Commands, and for each Command I want to loop through each Job. Is there a way to structure this with a single query? That is, I'd like Workflow.objects.all() to join in its dependent models, so I get a collection that has dependent objects already cached, so workflows[0].command_set.get() doesn't produce an additional query. Is this possible?

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  • Update tableview instantly as data pushed in core data iphone

    - by user336685
    I need to update the tableview as soon as the content is pushed in core data database. for this AppDelegate.m contains following code NSManagedObjectContext *moc = [self managedObjectContext]; NSFetchRequest *request = [[NSFetchRequest alloc] init]; [request setEntity:[NSEntityDescription entityForName:@"FeedItem" inManagedObjectContext:moc]]; //for loop // push data in code data & then save context [moc save:&error]; ZAssert(error == nil, @"Error saving context: %@", [error localizedDescription]); //for loop ends This code triggers following code from RootviewController.m - (void)controllerWillChangeContent:(NSFetchedResultsController*)controller { [[self tableView] beginUpdates]; } But this updates the tableview only at the end of the for loop ,the table does not get updated after immediate push in db. I tried following code but that didn't work - (void)controllerDidChangeContent:(NSFetchedResultsController *)controller { // In the simplest, most efficient, case, reload the table view. [self.tableView reloadData]; } I have been stuck with this problem for several days.Please help.Thanks in advance for solution.

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  • Are Scala "continuations" just a funky syntax for defining and using Callback Functions?

    - by Alex R
    And I mean that in the same sense that a C/Java for is just a funky syntax for a while loop. I still remember when first learning about the for loop in C, the mental effort that had to go into understanding the execution sequence of the three control expressions relative to the loop statement. Seems to me the same sort of effort has to be applied to understand Continuations (in Scala and I guess probably other languages). And then there's the obvious follow-up question... if so, then what's the point? It seems like a lot of pain (language complexity, programmer errors, unreadable programs, etc) for no gain.

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  • Java Convert ColorSpace of BufferedImage to CS_GRAY without using ConvertColorOp

    - by gmatt
    I know its possible to convert an image to CS_GRAY using public static BufferedImage getGrayBufferedImage(BufferedImage image) { BufferedImageOp op = new ColorConvertOp(ColorSpace .getInstance(ColorSpace.CS_GRAY), null); BufferedImage sourceImgGray = op.filter(image, null); return sourceImgGray; } however, this is a chokepoint of my entire program. I need to do this often, on 800x600 pixel images and takes about 200-300ms for this operation to complete, on average. I know I can do this alot faster by using one for loop to loop through the image data and set it right away. The code above on the other hand constructs a brand new 800x600 BufferedImage that is gray scale. I would rather just transform the image I pass in. Does any one know how to do this with a for loop and given that the image is RGB color space?

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  • Fermat factorization method limit

    - by Fakrudeen
    I am trying to implement Fermat's factorization [Algorithm C in Art of computer programming Vol. 2]. Unfortunately in my edition [ISBN 81-7758-335-2], this algorithm is printed incorrectly. what should be the condition on factor-inner loop below? I am running the loop till y <= n [passed in as limit]. (if (< limit y) 0 (factor-inner x (+ y 2) (- r y) limit)) Is there anyway to avoid this condition altogether, as it will double the speed of loop? (define (factor n) (let ( ( square-root (inexact->exact (floor (sqrt n))) ) ) (factor-inner (+ (* 2 square-root) 1) 1 (- (* square-root square-root) n) n) ) ) (define (factor-inner x y r limit) (if (= r 0) (/ (- x y) 2) (begin (display x)(display " ")(display y)(display " ")(display r)(newline) ;(sleep-current-thread 1) (if (< r 0) (factor-inner (+ x 2) y (+ r x) limit) (if (< limit y) 0 (factor-inner x (+ y 2) (- r y) limit)) ) ) ) )

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  • Problems with PHP System_Daemon and IMAP connection.

    - by mike
    I'm trying to create a PHP daemon that connects to an IMAP server and processes emails as they come in. I have it close to working, but the daemon keeps grabbing the original emails that it finds the first time the daemon is loaded. I believe the reason is because I'm opening the IMAP connection in the parent process. Example below: if ($imapConnection=imap_open($authhost,$user,$pass) or die()) { //start daemon while() { //Grab email headers $imapHeaders = imap_headers($imapConnection); $count = sizeof($imapHeaders) //loop the emails for($i = 1; $i <= $count, $i++) { //process the email //delete the email } System_Daemon::iterate(15); } } imap_close($imapConnection); I'd like to stay away from putting the IMAP connection within the loop. How can I keep the connection to the IMAP server outside of the loop and still get new emails?

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  • Why does PHP overwrite values when I iterate through this array twice (by reference, by value)

    - by jeremy
    If I iterate through an array twice, once by reference and then by value, PHP will overwrite the last value in the array if I use the same variable name for each loop. This is best illustrated through an example: $array = range(1,5); foreach($array as &$element) { $element *= 2; } print_r($array); foreach($array as $element) { } print_r($array); Output: Array ( [0] = 2 [1] = 4 [2] = 6 [3] = 8 [4] = 10 ) Array ( [0] = 2 [1] = 4 [2] = 6 [3] = 8 [4] = 8 ) Note that I am not looking for a fix, I am looking to understand why this is happening. Also note that it does not happen if the variable names in each loop are not each called $element, so I'm guessing it has to do with $element still being in scope and a reference after the end of the first loop.

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  • C# mysqlreader on same connection error

    - by dominiquel
    Hi, I must find a way to do this in C#, if possible... I must loop on my folder list (mysql table), and for each folder I instanciate I must do another query, but when I do this it says : "There is already an open DataReader associated with this Connection" and I am inside a mysqlreader loop already. Note that I have oversimplified the code just to show you, the fact is that I must do queries inside a mysqlreader loop, and it looks to be impossible as they are on the same connection? MySqlConnection cnx = new MySqlConnection(connexionString); cnx.Open(); MySqlCommand command= new MySqlCommand("SELECT * FROM folder WHERE folder_id = " + id, cnx); MySqlDataReader reader= commande.ExecuteReader(); while (reader.Read()) { this.folderList[this.folderList.Length] = new CFolder(reader.GetInt32"folder_id"), cnx); } reader.Close(); cnx.Close();

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  • Speed up math code in C# by writing a C dll?

    - by Projectile Fish
    I have a very large nested for loop in which some multiplications and additions are performed on floating point numbers. for (int i = 0; i < length1; i++) { s = GetS(i); c = GetC(i); for(int j = 0; j < length2; j++) { double oldU = u[j]; u[j] = c * oldU + s * omega[i][j]; omega[i][j] = c * omega[i][j] - s * oldU; } } This loop is taking up the majority of my processing time and is a bottleneck. Would I be likely to see any speed improvements if I rewrite this loop in C and interface to it from C#?

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  • C# How to pause/suspend a thread then continue it?

    - by Russ K
    I am making an application in C# which uses a winform as the GUI and a separate thread which is running in the background automatically changing things. Ex: public void run() { while(true) { printMessageOnGui("Hey"); Thread.Sleep(2000); . . } } How would I make it pause anywhere in the loop, because one iteration of the loop takes around 30 seconds. So I wouldnt want to pause it after its done one loop, I want to pause it on time. Thanks!

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  • Firefox HTML5 video playback inconsistancy

    - by Daniel Redwood
    Hey all, I've got an HTML5 video on a page. When tested locally, Chrome, Safari, and Opera work beautifully. Firefox plays it, but doesn't loop as efficiently as the others. The real problem is when it's tested off a server. Firefox doesn't play the video, but recognizes there is one there. I was wondering if all that open ended three-different-ways syntax can be swung in Firefox's favor. Thanks! HTML: <video id="vid_home" width="780" height="520" autoplay="autoplay" loop="loop"> <source src="Video/fernando.ogv" type="video/ogg" /> <source src="Video/fernando.m4v" type="video/mp4" /> Your browser does not support this videos playback. </video>

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  • Actionscript 3 svg XML parsing bug?

    - by Mahir
    Hey I get two different results when using the for each loop below. As far as I can tell there's no difference aside from attributes in the two XML literals. for each (var pathXML:XML in svg.path) { // do stuff... trace(pathXML.@stroke) } // This one works, the loop iterates once over the single path element... var svg:XML = <svg> <path stroke="#00FF00" /> </svg> // This one doesn't, the loop just exits. var svg:XML = <svg version="1.1" id="Layer_1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" x="0px" y="0px" width="612px" height="792px" viewBox="0 0 612 792" enable-background="new 0 0 612 792" xml:space="preserve"> <path fill="#FFFFFF" stroke="#000000" d="M160.333,372.444c0,0,17.778-115.555,60-63.333s27.778-106.666,78.889,40" /> </svg>

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  • PHP Possible Memory Leak

    - by dropson
    I have a script that loops through a database for images to convert with gd & imagick. I unset or replace all variables and objects in between each loop. For each loop, get_memory_usage(1) reveals a concurrent amount of memory used by that script. Which is expected. But, when I run "top", the %MEM column reports that this script, (same PID), increments with several percentages for each loop. I destroy all images when I'm done with them, and when I run get_defined_vars(); only the standard globals and a few variables I have is set. Why is "top" % Memory Usage different than what PHP reports? After 10 loops, PHP has taken 20% percetage of the system memory. I run php 5.2.6 on Debian 5

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  • Catching KeyboardInterrupt when working with PyGame

    - by Sebastian P.
    I have written a small Python application where I use PyGame for displaying some simple graphics. I have a somewhat simple PyGame loop going in the base of my application, like so: stopEvent = Event() # Just imagine that this eventually sets the stopEvent # as soon as the program is finished with its task. disp = SortDisplay(algorithm, stopEvent) def update(): """ Update loop; updates the screen every few seconds. """ while True: stopEvent.wait(options.delay) disp.update() if stopEvent.isSet(): break disp.step() t = Thread(target=update) t.start() while not stopEvent.isSet(): for event in pygame.event.get(): if event.type == pygame.QUIT: stopEvent.set() It works all fine and dandy for the normal program termination; if the PyGame window gets closed, the application closes; if the application finishes its task, the application closes. The trouble I'm having is, if I Ctrl-C in the Python console, the application throws a KeyboardInterrupt, but keeps on running. The question would therefore be: What have I done wrong in my update loop, and how do I rectify it so a KeyboardInterrupt causes the application to terminate?

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  • How to Execute an Oracle SQL Statements with VBScript

    - by Arno Conradie
    I am trying to execute an Oracle SQL statement or Oracle Functions through Microsoft VBScript and the loop throught the result set or display the value returned by the function So far I have managed to connect to Oracle via SQLPlus*, but now I am stuck. Can anybody help? Dim output Dim WshShell, oExec, input set WshShell = CreateObject("WScript.Shell") set oEnv=WshShell.Environment("Process") cmdString = "C:\Oracle\11g\product\11.1.0\ruby\BIN\sqlplus.exe -S stradmin/stradmin@ruby select * from dual" Set oExec = WshShell.Exec(cmdString) WScript.Echo "Status" & oExec.Status Do While oExec.Status = 0 WScript.Sleep 2 Loop input = "" Do While Not oExec.StdOut.AtEndOfStream input = input & oExec.StdOut.Read(1) Loop wscript.echo input

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  • LinkQ Exception

    - by Ravi
    Hi, I write Linq query for keep on fetching data from database. First loop table don't have record , so throwing exception. After first loop i have record in the database, my query is working properly. Below i specified my query give some suggestion first loop(no records in table) i have to modify query or query have to change. Ex: forloop(History history in historyList) { History history1 = (from p in context.History where p.TransferCode == history.TransferCode select p).First<History>() as History; if(history1 == null) { SaveToDataBase(history); } else { UpdateToDataBase(history1); } } Thinks

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  • Dynamic upsert in postgresql

    - by Daniel
    I have this upsert function that allows me to modify the fill_rate column of a row. CREATE FUNCTION upsert_fillrate_alarming(integer, boolean) RETURNS VOID AS ' DECLARE num ALIAS FOR $1; dat ALIAS FOR $2; BEGIN LOOP -- First try to update. UPDATE alarming SET fill_rate = dat WHERE equipid = num; IF FOUND THEN RETURN; END IF; -- Since its not there we try to insert the key -- Notice if we had a concurent key insertion we would error BEGIN INSERT INTO alarming (equipid, fill_rate) VALUES (num, dat); RETURN; EXCEPTION WHEN unique_violation THEN -- Loop and try the update again END; END LOOP; END; ' LANGUAGE 'plpgsql'; Is it possible to modify this function to take a column argument as well? Extra bonus points if there is a way to modify the function to take a column and a table.

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  • Displaying Nested Array Content with Time Delay in Flex

    - by MooCow
    I have a JSON array that look like this: (array here) I'm trying to use Flex to display each Project and its Milestone elements similar to a nested for-loop for 15 seconds per Milestone element before advancing to the next Project. I was shown a technique that works well for something without another array buried into it. var key:int = 0; var timer:timer = new timer (10000, project.length); timer.addEventListener (TimerEvent.TIMER, function showStuff(event:EVENT):void { trace project[key].projectName; key++; }); timer.start(); But that only replicate a single FOR-LOOP and not a nested FOR-LOOP. Any suggestions?

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  • How to create two dimensional array in jquery or js

    - by learner
    I need to create dynamic global two dimensional array in jquery or javascript My function is like this <script> var index = 0; var globalArray = new Array(); function createArray(){ var loop = globalArray[index].length; var name = $.("#uname").val(); if(loop == 0){ globalArray[index][0] = uname; }else{ globalArray[index][loop++] = uname; } } </script> <div><input type="text" id="uname"> <input type='button' value='save' onclick='createArray();'> </div> On click of that button I am getting this error "globalArray[index] is undefined" How can I create one global array using jquery or javascript like this. I dont want any hidden field and all. Please help me. Thanks

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  • How to run a program in python?

    - by Luka Mihaldinec
    this is my code. I'm trying to make a script which would run an .exe file from my computer. And this one isn't working :/ I think I'm using the wrong command.. I tried all the other commands like import os, os.startfile, but they won't work too. I think my code is just wrong :P loop=0 while loop==0: answer=raw_input("coded by: Narralol\n\n" "Pick a task:\n" "1) Start Minecraft.exe\n" "2) Start Minecraft_Server.jar\n" "3) Backup your server\n" "4) Copy the backup to your desktop\n" "5) Exit\n") if answer==1: execfile('D:\Games\Minecraft\Minecraft.exe') elif answer==2: execfile('D:\Games\Minecraft\Minecraft_server.jar') elif answer==5: loop=1

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  • Interrupting `while loop` with keyboard in Cython

    - by linello
    I want to be able to interrupt a long function with cython, using the usual CTRL+C interrupt command. My C++ long function is repeatedly called inside a while loop from Cython code, but I want to be able, during the loop, to send an "interrupt" and block the while loop. The interrupt also should wait the longFunction() to finish, so that no data are lost or kept in unknown status. This is one of my first implementation, which obviously doesn't work: computed=0; print "Computing long function..." while ( computed==0 ): try: computed = self.thisptr.aLongFunction() except (KeyboardInterrupt, SystemExit): computed=1 print '\n! Received keyboard interrupt.\n' break; (p.s. self.thisptr is the pointer to the current class which implements aLongFunction() )

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