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• Accelerometer gravity components

  - by Dvd

  Hi, I know this question is definitely solved somewhere many times already, please enlighten me if you know of their existence, thanks. Quick rundown: I want to compute from a 3 axis accelerometer the gravity component on each of these 3 axes. I have used 2 axes free body diagrams to work out the accelerometer's gravity component in the world X-Z, Y-Z and X-Y axes. But the solution seems slightly off, it's acceptable for extreme cases when only 1 accelerometer axis is exposed to gravity, but for a pitch and roll of both 45 degrees, the combined total magnitude is greater than gravity (obtained by Xa^2+Ya^2+Za^2=g^2; Xa, Ya and Za are accelerometer readings in its X, Y and Z axis). More detail: The device is a Nexus One, and have a magnetic field sensor for azimuth, pitch and roll in addition to the 3-axis accelerometer. In the world's axis (with Z in the same direction as gravity, and either X or Y points to the north pole, don't think this matters much?), I assumed my device has a pitch (P) on the Y-Z axis, and a roll (R) on the X-Z axis. With that I used simple trig to get: Sin(R)=Ax/Gxz Cos(R)=Az/Gxz Tan(R)=Ax/Az There is another set for pitch, P. Now I defined gravity to have 3 components in the world's axis, a Gxz that is measurable only in the X-Z axis, a Gyz for Y-Z, and a Gxy for X-Y axis. Gxz^2+Gyz^2+Gxy^2=2*G^2 the 2G is because gravity is effectively included twice in this definition. Oh and the X-Y axis produce something more exotic... I'll explain if required later. From these equations I obtained a formula for Az, and removed the tan operations because I don't know how to handle tan90 calculations (it's infinity?). So my question is, anyone know whether I did this right/wrong or able to point me to the right direction? Thanks! Dvd

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• Memory Profiling with DotTrace Questions

  - by cam

  I ran dotTrace on my application (which is having some issues). IntPtr System.Windows.Forms.UnsafeNativeMethods.CallWindowProc(IntPtr, IntPtr, Int32, IntPtr, IntPtr) Void System.Windows.Forms.UnsafeNativeMethods.WaitMessage() Are the two main functions that came up, taking about 94% of the application time. Since I didn't know what these two functions were, I ran through my code line by line. It runs smooth and efficiently until a point where it just hangs. "newFrm.Show()". The newFrm only contains a textbox. The larger the file I load into the text box (it's a notepad program), the longer it takes. Now normally this makes sense, but it takes about 30 seconds for a 167 kB file. Now I'm not sure what to do. It runs incredibly slow/stops functioning when you load a textfile and try to resize the window containing the text file too. Then I realized that it is only struggling to open text files with a long string of hex inside (ie) "XX-XX-XX-" etc. With other similarly sized files it struggles with resizing somewhat, but opens within a couple seconds. Does this have something to do with the textbox properties? I've set it to multiline and set maximum characters to 0 (so unlimited). How do I solve this issue? Is there some way I can see what is being called in those functions?

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• F# Inline Function Specialization

  - by Ben

  Hi, My current project involves lexing and parsing script code, and as such I'm using fslex and fsyacc. Fslex LexBuffers can come in either LexBuffer<char> and LexBuffer<byte> varieties, and I'd like to have the option to use both. In order to user both, I need a lexeme function of type ^buf - string. Thus far, my attempts at specialization have looked like: let inline lexeme (lexbuf: ^buf) : ^buf -> string where ^buf : (member Lexeme: char array) = new System.String(lexbuf.Lexeme) let inline lexeme (lexbuf: ^buf) : ^buf -> string where ^buf : (member Lexeme: byte array) = System.Text.Encoding.UTF8.GetString(lexbuf.Lexeme) I'm getting a type error stating that the function body should be of type ^buf -> string, but the inferred type is just string. Clearly, I'm doing something (majorly?) wrong. Is what I'm attempting even possible in F#? If so, can someone point me to the proper path? Thanks!

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• jQuery .each() function. Resetting the index?

  - by Michael

  Hi there, I have multiple lists with the same class. I'd like to loop each list and its LI's and prepend the current number before each. The current code I have is: $jQuery(".numberList li").each(function(i) { var index = i + 1; $jQuery(this).prepend("<span>" + index + "</span>"); }); The problem is, is that the index doesn't restart back at 0 for each list it goes through, it just keeps going up. For example, the output I get now is: First list 1. item 2. item 3. item Second list 4. item 5. item 6. item Second list should start at 1 again by having the index back at 0. Could someone point out where I'm going wrong? I'm not a jQuery expert or anything...clearly :) Many thanks, Michael.

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• Why are virtual methods considered early bound?

  - by AspOnMyNet

  One definition of binding is that it is the act of replacing function names with memory addresses. a) Thus I assume early binding means function calls are replaced with memory addresses during compilation process, while with late binding this replacement happens during runtime? b) Why are virtual methods also considered early bound (thus the target method is found at compile time, and code is created that will call this method)? As far as I know, with virtual methods the call to actual method is resolved only during runtime and not compile time?! thanx EDIT: 1) A a=new A(); a.M(); As far as I know, it is not known at compile time where on the heap (thus at which memory address ) will instance a be created during runtime. Now, with early binding the function calls are replaced with memory addresses during compilation process. But how can compiler replace function call with memory address, if it doesn’t know where on the heap will object a be created during runtime ( here I’m assuming the address of method a.M will also be at same memory location as a )? 2) v-table calls are neither early nor late bound. Instead there's an offset into a table of function pointers. The offset is fixed at compile time, but which table the function pointer is chosen from depends on the runtime type of the object (the object contains a hidden pointer to its v-table), so the final function address is found at runtime. But assuming the object of type T is created via reflection ( thus app doesn’t even know of existence of type T ), then how can at compile time exist an entry point for that type of object?

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• Background problem on UITableView

  - by f0rz

  Hi ! I have come to a problem, wich I have no idea how to solve. Can anyone think outside the box and point me to right directions? I would be very thankfull ! The problem. I have a UITableView containing a first row wich is always the same (a empty row with repeating background) Next rows are bounch of dynamic data rows. I have set the yellow background on my UITableView in IBuilder, My cells (except first row) have white background with code: UIView* backgroundView = [ [ [ UIView alloc ] initWithFrame:CGRectZero ] autorelease ]; backgroundView.backgroundColor = [UIColor colorWithRed: 0.96078431372549 green: 0.96078431372549 blue: 0.96078431372549 alpha: 1.0]; cell.backgroundView = backgroundView; for ( UIView* view in cell.contentView.subviews ) { view.backgroundColor = [ UIColor clearColor ]; } The example yellow background, I only want to be showed at the top. As u see img example below. The thing is I dont want to have yellow background under the last datarow, I want to contain same white color I have on the cells. This should be white as the cells. Not yellow. Thank u for your time. Regards

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• How to set up django-admin.py on windows vista?

  - by shin

  I manage to install Django after some struggles by using setup.py install on Windows Vista Now I tried to use django-admin.py but it is not working. According to this document, http://docs.djangoproject.com/en/dev/ref/django-admin/ The django-admin.py script should be on your system path if you installed Django via its setup.py utility. If it’s not on your path, ... For Windows users, who do not have symlinking functionality available, you can copy django-admin.py to a location on your existing path or edit the PATH settings (under Settings - Control Panel - System - Advanced - Environment...) to point to its installed location. I checked ComputerpropertiesEnvironment Variables, but path to django-admin.py is not in anywhere. So I added C:\Python25\Lib\site-packages\django\bin which is the folder of django-admin.py in User variables for shin Variable PATH, Value C:\Program Files\Google\google_appengine\;C:\Python25\Lib\site-packages\django\bin\ Am I supposed to add to System variables?? But it still does not work. Could anyone tell me how to add the Path in Environment Variables please? Thanks in advance.

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• I am confused -- Will this code always work?

  - by Shekhar

  Hello, I have written this piece of code public class Test{ public static void main(String[] args) { List<Integer> list = new ArrayList<Integer>(); for(int i = 1;i<= 4;i++){ new Thread(new TestTask(i, list)).start(); } while(list.size() != 4){ // this while loop required so that all threads complete their work } System.out.println("List "+list); } } class TestTask implements Runnable{ private int sequence; private List<Integer> list; public TestTask(int sequence, List<Integer> list) { this.sequence = sequence; this.list = list; } @Override public void run() { list.add(sequence); } } This code works and prints all the four elements of list on my machine. My question is that will this code always work. I think there might be a issue in this code when two/or more threads add element to this list at the same point. In that case it while loop will never end and code will fail. Can anybody suggest a better way to do this? I am not very good at multithreading and don't know which concurrent collection i can use? Thanks Shekhar

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• Nhibernate - stuck with detached criteria (asp.net mvc 1 with nhibernate 2) c#

  - by Jen

  OK so I can't find a good example of this so I can better understand how to use detached criteria (assuming that's what I want to use in the first place). I have 2 tables. Placement and PlacementSupervisor My PlacementSupervisor table has a FK of PlacementID which relates to Placement.PlacementID - though my nhibernate model class has PlacementSupervisor . Placement (rather than specifically specifying a property of placement ID - not sure if this is important). What I am trying to do is - if values are passed through for the supervisor ID I want to restrict placements with that supervisor id. Have tried: ICriteria query = m_PlacementRepository.QueryAlias("p") .... if (criteria.SupervisorId > 0 && !string.IsNullOrEmpty(criteria.SupervisorTypeId)) { DetachedCriteria entityQuery = DetachedCriteria.For<PlacementSupervisor>("sup") .Add(Restrictions.And( Restrictions.Eq("sup.supervisorId", criteria.SupervisorId), Restrictions.Eq("sup.supervisorTypeId", criteria.SupervisorTypeId) )) .SetProjection(Projections.ProjectionList() .AddPropertyAlias("Placement.PlacementId", "PlacementId") ); query.Add(Subqueries.PropertyIn("p.PlacementId", entityQuery)); } Which just gives me the error: Could not find a matching criteria info provider to: (sup.supervisorId = 5 and sup.supervisorTypeId = U) Firstly supervisorTypeId is a string. Secondly I don't understand how to achieve what I'm trying to do so have just been trying various combinations of projections, and property aliases and subquery options..as I don't get how I'm supposed to join to another table/entity when the FK key sits in the second table. Can someone point me in the right direction. It seems like such an easy thing to do from a data perspective that hopefully I'm just missing something obvious!!

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• NSURLConnection receives data even if no data was thrown back

  - by Anna Fortuna

  Let me explain my situation. Currently, I am experimenting long-polling using NSURLConnection. I found this and I decided to try it. What I do is send a request to the server with a timeout interval of 300 secs. (or 5 mins.) Here is a code snippet: NSURL *url = [NSURL URLWithString:urlString]; NSURLRequest *request = [NSURLRequest requestWithURL:url cachePolicy:NSURLCacheStorageAllowedInMemoryOnly timeoutInterval:300]; NSData *data = [NSURLConnection sendSynchronousRequest:request returningResponse:&resp error:&err]; Now I want to test if the connection will "hold" the request if no data was thrown back from the server, so what I did was this: if (data != nil) [self performSelectorOnMainThread:@selector(dataReceived:) withObject:data waitUntilDone:YES]; And the function dataReceived: looks like this: - (void)dataReceived:(NSData *)data { NSLog(@"DATA RECEIVED!"); NSString *string = [NSString stringWithUTF8String:[data bytes]]; NSLog(@"THE DATA: %@", string); } Server-side, I created a function that will return a data once it fits the arguments and returns none if nothing fits. Here is a snippet of the PHP function: function retrieveMessages($vardata) { if (!empty($vardata)) { $result = check_data($vardata) //check_data is the function which returns 1 if $vardata //fits the arguments, and 0 if it fails to fit if ($result == 1) { $jsonArray = array('Data' => $vardata); echo json_encode($jsonArray); } } } As you can see, the function will only return data if the $result is equal to 1. However, even if the function returns nothing, NSURLConnection will still perform the function dataReceived: meaning the NSURLConnection still receives data, albeit an empty one. So can anyone help me here? How will I perform long-polling using NSURLConnection? Basically, I want to maintain the connection as long as no data is returned. So how will I do it? NOTE: I am new to PHP, so if my code is wrong, please point it out so I can correct it.

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• Spring aop multiple pointcuts & advice but only the last one is working

  - by Jarle Hansen

  I have created two Spring AOP pointcuts that are completely separate and will be woven in for different parts of the system. The pointcuts are used in two different around advices, these around-advices will point to the same Java method. How the xml-file looks: <aop:config> <aop:pointcut expression="execution(......)" id="pointcutOne" /> <aop:pointcut expression="execution(.....)" id="pointcurTwo" /> <aop:aspect id="..." ref="springBean"> <aop:around pointcut-ref="pointcutOne" method="commonMethod" /> <aop:aroung pointcut-ref="pointcutTwo" method="commonMethod" /> </aop:aspect> </aop:config> The problem is that only the last pointcut works (if I change the order "pointcutOne" works because it is last). I have gotten it to work by creating one big pointcut, but I would like to have them separate. Any suggestions to why only one of the pointcuts works at a time?

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• Trouble with custom WPF Panel-derived class

  - by chaiguy

  I'm trying to write a custom Panel class for WPF, by overriding MeasureOverride and ArrangeOverride but, while it's mostly working I'm experiencing one strange problem I can't explain. In particular, after I call Arrange on my child items in ArrangeOverride after figuring out what their sizes should be, they aren't sizing to the size I give to them, and appear to be sizing to the size passed to their Measure method inside MeasureOverride. Am I missing something in how this system is supposed to work? My understanding is that calling Measure simply causes the child to evaluate its DesiredSize based on the supplied availableSize, and shouldn't affect its actual final size. Here is my full code (the Panel, btw, is intended to arrange children in the most space-efficient manner, giving less space to rows that don't need it and splitting remaining space up evenly among the rest--it currently only supports vertical orientation but I plan on adding horizontal once I get it working properly): protected override Size MeasureOverride( Size availableSize ) { foreach ( UIElement child in Children ) child.Measure( availableSize ); return availableSize; } protected override System.Windows.Size ArrangeOverride( System.Windows.Size finalSize ) { double extraSpace = 0.0; var sortedChildren = Children.Cast<UIElement>().OrderBy<UIElement, double>( new Func<UIElement, double>( delegate( UIElement child ) { return child.DesiredSize.Height; } ) ); double remainingSpace = finalSize.Height; double normalSpace = 0.0; int remainingChildren = Children.Count; foreach ( UIElement child in sortedChildren ) { normalSpace = remainingSpace / remainingChildren; if ( child.DesiredSize.Height < normalSpace ) // if == there would be no point continuing as there would be no remaining space remainingSpace -= child.DesiredSize.Height; else { remainingSpace = 0; break; } remainingChildren--; } extraSpace = remainingSpace / Children.Count; double offset = 0.0; foreach ( UIElement child in Children ) { //child.Measure( new Size( finalSize.Width, normalSpace ) ); double value = Math.Min( child.DesiredSize.Height, normalSpace ) + extraSpace; child.Arrange( new Rect( 0, offset, finalSize.Width, value ) ); offset += value; } return finalSize; }

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• Why doesn't IB see my IBAction?

  - by Dan Ray

  I've been staring at this for way too long. There's nothing fancy happening here, and I've done this dozens of times, yet Interface Builder steadfastly refuses to provide me an action target for -(IBAction)slideDirections. I'm at the point where I'm willing to post publicly and feel stupid. So let 'er rip. Here's my .h: #import <UIKit/UIKit.h> #import <MapKit/MapKit.h> @interface PulseDetailController : UIViewController { NSDictionary *pulse; IBOutlet MKMapView *map; IBOutlet UIWebView *directions; IBOutlet UIView *directionsSlider; BOOL directionsExtended; IBOutlet UILabel *vendor; IBOutlet UILabel *offer; IBOutlet UILabel *offerText; IBOutlet UILabel *hours; IBOutlet UILabel *minutes; IBOutlet UILabel *seconds; IBOutlet UILabel *distance } @property (nonatomic, retain) NSDictionary *pulse; @property (nonatomic, retain) MKMapView *map; @property (nonatomic, retain) UIWebView *directions; @property (nonatomic, retain) UIView *directionsSlider; @property (nonatomic) BOOL directionsExtended; @property (nonatomic, retain) UILabel *vendor; @property (nonatomic, retain) UILabel *offer; @property (nonatomic, retain) UILabel *offerText; @property (nonatomic, retain) UILabel *hours; @property (nonatomic, retain) UILabel *minutes; @property (nonatomic, retain) UILabel *seconds; @property (nonatomic, retain) UILabel *distance; -(IBAction)slideDirections; @end

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• Should we deploy a Webkit browser for our intranet applications?

  - by Jeff Meatball Yang

  At my place of employment, we are increasingly finding it difficult to develop for IE, which was historically the easiest browser to target, from an intranet-app point of view. It was already deployed. It already understood NTLM authentication, thus well integrated with our domain-level security. It had neat, albeit non-standard features such as XMLDOM and XmlHTTP. Now, we are increasingly irritated by issues presented by IE: There are several versions: IE 7, 8, and soon 9 beta, which all have slightly different issues related to performance, functionality (especially re:security and zones), and aesthetics. IE 7 and 8 are slower than Webkit-based browsers. Period. There are technology limitations such as missing canvas element, CSS bugs, etc. that make it hard to use 3rd party packages or even consistently write code across IE versions. Users are increasingly using Firefox or Chrome, even for intranet use. Does anyone have experience with making a transition? Any advice would be welcome.

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• Natural problems to solve using closures

  - by m.u.sheikh

  I have read quite a few articles on closures, and, embarassingly enough, I still don't understand this concept! Articles explain how to create a closure with a few examples, but I don't see any point in paying much attention to them, as they largely look contrived examples. I am not saying all of them are contrived, just that the ones I found looked contrived, and I dint see how even after understanding them, I will be able to use them. So in order to understand closures, I am looking at a few real problems, that can be solved very naturally using closures. For instance, a natural way to explain recursion to a person could be to explain the computation of n!. It is very natural to understand a problem like computing the factorial of a number using recursion. Similarly, it is almost a no-brainer to find an element in an unsorted array by reading each element, and comparing with the number in question. Also, at a different level, doing Object-oriented programming also makes sense. So I am trying to find a number of problems that could be solved with or without closures, but using closures makes thinking about them and solving them easier. Also, there are two types to closures, where each call to a closure can create a copy of the environment variables, or reference the same variables. So what sort of problems can be solved more naturally in which of the closure implementations?

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• Prevent TEXTAREAs scroll by themselves on IE8

  - by Justin Grant

  IE8 has a known bug (per connect.microsoft.com) where typing or pasting text into a TEXTAREA element will cause the textarea to scroll by itself. This is hugely annoying and shows up in many community sites, including Wikipedia. The repro is this: open the HTML below with IE8 (or use any long page on wikipedia which will exhibit the same problem until they fix it) size the browser full-screen paste a few pages of text into the TEXTAREA move the scrollbar to the middle position now type one character into the textarea Expected: nothing happens Actual: scrossing happens on its own, and the insertion point ends up near the bottom of the textarea! Below is repro HTML (can also see this live on the web here: http://en.wikipedia.org/w/index.php?title=Text_box&action=edit) <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" > <body> <div style="width: 80%"> <textarea rows="20" cols="80" style="width:100%;" ></textarea> </div> </body> </html>

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• Java CountDownLatch used to wait for JFrame to dispose

  - by Brian

  I have referenced this previous question as well as other sources, but cannot get CountDownLatch to work correctly. Background: mainFrame creates new Frame called dataEntryFrame. When dataEntryFrame "Submit" button is clicked, record added to database and dataEntryFrame disposed. At this point, mainFrame should clear and reload a jList that shows all records. Issue: When dataEntryFrame loads, java freezes, dataEntryFrame components never load. I cannot get past this part... then, in the DataEntryFrame, CountDownLatch should only decrements after the submit button is clicked, successfully adds a record to a database table, and disposes itself. Or when the user clicks cancel... Code: From MainFrame CountDownLatch dataEntryDone = new CountDownLatch(1); DataEntryFrame f = new DataEntryFrame(dataEntryDone); Thread newThread = new Thread(f); newThread.start(); dataEntryDone.await(); Code: From DataEntryFrame public void run(){ initComponents(); loadOtherData(); this.setVisible(true); } void submit(){ addRecord(); this.dispose() dataEntryDone.countDown(); }

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• Application.ProcessMessages hangs???

  - by X-Ray

  my single threaded delphi 2009 app (not quite yet complete) has started to have a problem with Application.ProcessMessages hanging. my app has a TTimer object that fires every 100 ms to poll an external device. i use Application.ProcessMessages to update the screen when something changes so the app is still responsive. one of these was in a grid OnMouseDown event. in there, it had an Application.ProcessMessages that essentially hung. removing that was no problem except that i soon discovered another Application.ProcessMessages that was also blocking. i think what may be happening to me is that the TTimer is--in the app mode i'm currently debugging--probably taking too long to complete. i have prevented the TTimer.OnTimer event hander from re-entering the same code (see below): procedure TfrmMeas.tmrCheckTimer(Sender: TObject); begin if m_CheckTimerBusy then exit; m_CheckTimerBusy:=true; try PollForAndShowMeasurements; finally m_CheckTimerBusy:=false; end; end; what places would it be a bad practice to call Application.ProcessMessages? OnPaint routines springs to mind as something that wouldn't make sense. any general recommendations? i am surprised to see this kind of problem arise at this point in the development!

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• DataSets to POCOs - an inquiry regarding DAL architecture

  - by alexsome

  Hello all, I have to develop a fairly large ASP.NET MVC project very quickly and I would like to get some opinions on my DAL design to make sure nothing will come back to bite me since the BL is likely to get pretty complex. A bit of background: I am working with an Oracle backend so the built-in LINQ to SQL is out; I also need to use production-level libraries so the Oracle EF provider project is out; finally, I am unable to use any GPL or LGPL code (Apache, MS-PL, BSD are okay) so NHibernate/Castle Project are out. I would prefer - if at all possible - to avoid dishing out money but I am more concerned about implementing the right solution. To summarize, there are my requirements: Oracle backend Rapid development (L)GPL-free Free I'm reasonably happy with DataSets but I would benefit from using POCOs as an intermediary between DataSets and views. Who knows, maybe at some point another DAL solution will show up and I will get the time to switch it out (yeah, right). So, while I could use LINQ to convert my DataSets to IQueryable, I would like to have a generic solution so I don't have to write a custom query for each class. I'm tinkering with reflection right now, but in the meantime I have two questions: Are there any problems I overlooked with this solution? Are there any other approaches you would recommend to convert DataSets to POCOs? Thanks in advance.

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• How to find Tomcat's PID and kill it in python?

  - by 4herpsand7derpsago

  Normally, one shuts down Apache Tomcat by running its shutdown.sh script (or batch file). In some cases, such as when Tomcat's web container is hosting a web app that does some crazy things with multi-threading, running shutdown.sh gracefully shuts down some parts of Tomcat (as I can see more available memory returning to the system), but the Tomcat process keeps running. I'm trying to write a simple Python script that: Calls shutdown.sh Runs ps -aef | grep tomcat to find any process with Tomcat referenced If applicable, kills the process with kill -9 <PID> Here's what I've got so far (as a prototype - I'm brand new to Python BTW): #!/usr/bin/python # Imports import sys import subprocess # Load from imported module. if __init__ == "__main__": main() # Main entry point. def main(): # Shutdown Tomcat shutdownCmd = "sh ${TOMCAT_HOME}/bin/shutdown.sh" subprocess.call([shutdownCmd], shell=true) # Check for PID grepCmd = "ps -aef | grep tomcat" grepResults = subprocess.call([grepCmd], shell=true) if(grepResult.length > 1): # Get PID and kill it. pid = ??? killPidCmd = "kill -9 $pid" subprocess.call([killPidCmd], shell=true) # Exit. sys.exit() I'm struggling with the middle part - with obtaining the grep results, checking to see if their size is greater than 1 (since grep always returns a reference to itself, at least 1 result will always be returned, methinks), and then parsing that returned PID and passing it into the killPidCmd. Thanks in advance!

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• SQL - Updating records based on most recent date

  - by Remnant

  I am having difficulty updating records within a database based on the most recent date and am looking for some guidance. By the way, I am new to SQL. As background, I have a windows forms application with SQL Express and am using ADO.NET to interact with the database. The application is designed to enable the user to track employee attendance on various courses that must be attended on a periodic basis (e.g. every 6 months, every year etc.). For example, they can pull back data to see the last time employees attended a given course and also update attendance dates if an employee has recently completed a course. I have three data tables: EmployeeDetailsTable - simple list of employees names, email address etc., each with unique ID CourseDetailsTable - simple list of courses, each with unique ID (e.g. 1, 2, 3 etc.) AttendanceRecordsTable - has 3 columns { EmployeeID, CourseID, AttendanceDate, Comments } For any given course, an employee will have an attendance history i.e. if the course needs to be attended each year then they will have one record for as many years as they have been at the company. What I want to be able to do is to update the 'Comments' field for a given employee and given course based on the most recent attendance date. What is the 'correct' SQL syntax for this? I have tried many things (like below) but cannot get it to work: UPDATE AttendanceRecordsTable SET Comments = @Comments WHERE AttendanceRecordsTable.EmployeeID = (SELECT EmployeeDetailsTable.EmployeeID FROM EmployeeDetailsTable WHERE (EmployeeDetailsTable.LastName =@ParameterLastName AND EmployeeDetailsTable.FirstName =@ParameterFirstName) AND AttendanceRecordsTable.CourseID = (SELECT CourseDetailsTable.CourseID FROM CourseDetailsTable WHERE CourseDetailsTable.CourseName =@CourseName)) GROUP BY MAX(AttendanceRecordsTable.LastDate) After much googling, I discovered that MAX is an aggregate function and so I need to use GROUP BY. I have also tried using the HAVING keyword but without success. Can anybody point me in the right direction? What is the 'conventional' syntax to update a database record based on the most recent date?

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• Project euler problem 45

  - by Peter

  Hi, I'm not yet a skilled programmer but I thought this was an interesting problem and I thought I'd give it a go. Triangle, pentagonal, and hexagonal numbers are generated by the following formulae: Triangle T_(n)=n(n+1)/2 1, 3, 6, 10, 15, ... Pentagonal P_(n)=n(3n-1)/2 1, 5, 12, 22, 35, ... Hexagonal H_(n)=n(2n-1) 1, 6, 15, 28, 45, ... It can be verified that T_(285) = P_(165) = H_(143) = 40755. Find the next triangle number that is also pentagonal and hexagonal. Is the task description. I know that Hexagonal numbers are a subset of triangle numbers which means that you only have to find a number where Hn=Pn. But I can't seem to get my code to work. I only know java language which is why I'm having trouble finding a solution on the net womewhere. Anyway hope someone can help. Here's my code public class NextNumber { public NextNumber() { next(); } public void next() { int n = 144; int i = 165; int p = i * (3 * i - 1) / 2; int h = n * (2 * n - 1); while(p!=h) { n++; h = n * (2 * n - 1); if (h == p) { System.out.println("the next triangular number is" + h); } else { while (h > p) { i++; p = i * (3 * i - 1) / 2; } if (h == p) { System.out.println("the next triangular number is" + h); break; } else if (p > h) { System.out.println("bummer"); } } } } } I realize it's probably a very slow and ineffecient code but that doesn't concern me much at this point I only care about finding the next number even if it would take my computer years :) . Peter

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• How to use google maps API with multiple markers on the same map

  - by Maen

  So, i have the following script to use the google maps API, its all fine, but i need to create a map that has more than one Marker (the balloon shaped icon pointing to something) and i need each of those markers to point on a different area of the map (i.e. different coordinates), how can i do it? <script type="text/javascript"> function load() { var map = new GMap2(document.getElementById("map")); var marker = new GMarker(new GLatLng(<%=coordinates%>)); var html="<img src='simplemap_logo.jpg' width='20' height='20'/> " + "<%=maptitle%><br/>" + "<%=text%>"; map.setCenter(new GLatLng(<%=coordinates%>), <%=zoom%>) map.setMapType(G_HYBRID_MAP); map.addOverlay(marker); map.addControl(new GLargeMapControl()); map.addControl(new GScaleControl()); map.addControl(new GMapTypeControl()); marker.openInfoWindowHtml(html); } //]]> </script> One more question, if i pass the Script text as a variable, lets say something like: <script type="text/javascript"> <%=ScriptText%> </script> and my <%=ScriptText% will be a string which i will build and assign its value to a Friend or Public variable called ScriptText, will it still run and work properly? (i am doing this to make my script dynamic and different based on how i build it as a STRING, due to my illiteracy in javascripting ;P)

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• correct format for function prototype

  - by yCalleecharan

  Hi, I'm writing to a text file using the following declaration: void create_out_file(char file_name[],long double *z1){ FILE *out; int i; if((out = fopen(file_name, "w+")) == NULL){ fprintf(stderr, "***> Open error on output file %s", file_name); exit(-1); } for(i = 0; i < ARRAY_SIZE; i++) fprintf(out, "%.16Le\n", z1[i]); fclose(out); } Where z1 is an long double array of length ARRAY_SIZE. The calling function is: create_out_file("E:/first67/jz1.txt", z1); I defined the prototype as: void create_out_file(char file_name[], long double z1[]); which I'm putting before "int main" but after the preprocessor directives. My code works fine. I was thinking of putting the prototype as void create_out_file(char file_name[],long double *z1). Is this correct? *z1 will point to the first array element of z1. Is my declaration and prototype good programming practice? Thanks a lot...

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• Problem with futures in c++0x .

  - by Eternal Learner

  Hi, I have written a small program , to understand how futures work in c++0x. while running the code I get an error like " error: 'printEn' was not declared in this scope". I am unable to understand what the problem is..Kindly point out what I am doing wrong here and if possible write the correct code for the same.. #include <future> #include <iostream> using namespace std; int printFn() { for(int i = 0; i < 100; i++) { cout << "thread " << i << endl; } return 1; } int main() { future<int> the_answer2=async(printEn); future<int> the_answer1=async(printEn); return 0; }

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