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  • Linux - serial port read returning EAGAIN...

    - by Andre
    Hello all! I am having some trouble reading some data from a serial port I opened the following way. I've used this instance of code plenty of times and all worked fine, but now, for some reason that I cant figure out, I am completely unable to read anything from the serial port. I am able to write and all is correctly received on the other end, but the replies (which are correctly sent) are never received (No, the cables are all ok ;) ) The code I used to open the serial port is the following: fd = open("/dev/ttyUSB0", O_RDWR | O_NONBLOCK | O_NOCTTY); if (fd == -1) { Aviso("Unable to open port"); return (fd); } else { //Get the current options for the port... bzero(&options, sizeof(options)); /* clear struct for new port settings */ tcgetattr(fd, &options); /*-- Set baud rate -------------------------------------------------------*/ if (cfsetispeed(&options, SerialBaudInterp(BaudRate))==-1) perror("On cfsetispeed:"); if (cfsetospeed(&options, SerialBaudInterp(BaudRate))==-1) perror("On cfsetospeed:"); //Enable the receiver and set local mode... options.c_cflag |= (CLOCAL | CREAD); options.c_cflag &= ~PARENB; /* Parity disabled */ options.c_cflag &= ~CSTOPB; options.c_cflag &= ~CSIZE; /* Mask the character size bits */ options.c_cflag |= SerialDataBitsInterp(8); /* CS8 - Selects 8 data bits */ options.c_cflag &= ~CRTSCTS; // disable hardware flow control options.c_iflag &= ~(IXON | IXOFF | IXANY); // disable XON XOFF (for transmit and receive) options.c_cflag |= CRTSCTS; /* enable hardware flow control */ options.c_cc[VMIN] = 0; //min carachters to be read options.c_cc[VTIME] = 0; //Time to wait for data (tenths of seconds) //Set the new options for the port... tcflush(fd, TCIFLUSH); if (tcsetattr(fd, TCSANOW, &options)==-1) { perror("On tcsetattr:"); } PortOpen[ComPort] = fd; } return PortOpen[ComPort]; After the port is initializeed I write some stuff to it through simple write command... int nc = write(hCom, txchar, n); where hCom is the file descriptor (and it's ok), and (as I said) this works. But... when I do a read afterwards, I get a "Resource Temporarily Unavailable" error from errno. I tested select to see when the file descriptor had something t read... but it always times out! I read data like this: ret = read(hCom, rxchar, n); and I always get an EAGAIN and I have no idea why. All help would be appreciated. Cheers

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  • Getting problem while capturing image through web cam in Java -OpenCV code.

    - by Chetan
    Hi.. I am developing Face detector using OpenCV library in java... I have written sample code for this,but it is giving Error while capturing image. can any one help please. Here is the code import java.awt.; import java.awt.event.; import java.awt.image.MemoryImageSource; import hypermedia.video.OpenCV; @SuppressWarnings("serial") public class FaceDetection extends Frame implements Runnable { ///Main method. public static void main(String[] args) { //System.out.println( "\nOpenCV face detection sample\n" ); new FaceDetection(); } // program execution frame rate (millisecond) final int FRAME_RATE = 1000/30; OpenCV cv = null; // OpenCV Object Thread t = null; // the sample thread // the input video stream image Image frame = null; // list of all face detected area Rectangle[] squares = new Rectangle[0]; //** Setup Frame and Object(s). FaceDetection() { super( "Face Detection" ); // OpenCV setup cv = new OpenCV(); //cv.capture(1, 1, 100); cv.capture( 320, 240 ); cv.cascade( OpenCV.CASCADE_FRONTALFACE_ALT ); // frame setup this.setBounds( 100, 100, cv.width, cv.height ); this.setBackground( Color.BLACK ); this.setVisible( true ); this.addKeyListener( new KeyAdapter() { public void keyReleased( KeyEvent e ) { if ( e.getKeyCode()==KeyEvent.VK_ESCAPE ) { // ESC : release OpenCV resources cv.dispose(); System.exit(0); } } } ); // start running program t = new Thread( this ); t.start(); } // Draw video frame and each detected faces area. public void paint( Graphics g ) { // draw image g.drawImage( frame, 0, 0, null ); // draw squares g.setColor( Color.RED ); for( Rectangle rect : squares ) g.drawRect( rect.x, rect.y, rect.width, rect.height ); } @SuppressWarnings("static-access") public void run() { while( t!=null && cv!=null ) { try { t.sleep( FRAME_RATE ); // grab image from video stream cv.read(); // create a new image from cv pixels data MemoryImageSource mis = new MemoryImageSource( cv.width, cv.height, cv.pixels(), 0, cv.width ); frame = createImage( mis ); // detect faces squares = cv.detect( 1.2f, 2, OpenCV.HAAR_DO_CANNY_PRUNING, 20, 20 ); // of course, repaint repaint(); } catch( InterruptedException e ) {;} } } } Error while starting capture : device 0

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  • WPF Animation FPS vs. CPU usage - Am I expecting too much?

    - by Cory Charlton
    Working on a screen saver for my wife, http://cchearts.codeplex.com/, and while I've been able to improve FPS on lower end machines (switch from Path to StreamGeometry, use DrawingVisual instead of UserControl, etc) the CPU usage still seems very high. Here's some numbers I ran from a few 5 minute sampling periods: ~60FPS 35% average CPU on Core 2 Duo T7500 @ 2.2GHz, 3GB ram, NVIDIA Quadro NVS 140M (128MB), Vista [My dev laptop] ~40FPS 50% average CPU on Pentium D @ 3.4GHz, 1.5GB ram, Standard VGA Graphics Adapter (unknown), 2003 Server [A crappy desktop] I can understand the lower frame rate and higher CPU usage on the crappy desktop but it still seems pretty high and 35% on my dev laptop seems high as well. I'd really like to analyze the application to get more details but I'm having issues there as well so I'm wondering if I'm doing something wrong (never profiled WPF before). WPF Performance Suite: Process Launch Error Unable to attach to process: CCHearts.exe Do you want to kill it? This error message occurs when I click cancel after attempting launch. If I don't click cancel it sits there idle, I guess waiting to attach. Performance Explorer: Could not launch C:\Projects2\CC.Hearts\CC.Hearts\bin\Debug (USEVISUAL)\CCHearts.exe. Previous attempt to profile the application finished unsuccessfully. Please restart the application. Output Window from Performance: Profiling started. Profiling process ID 5360 (CCHearts). Process ID 5360 has exited. Data written to C:\Projects2\CC.Hearts\CCHearts100608.vsp. Profiling finished. PRF0025: No data was collected. Profiling complete. So I'm stuck wanting to improve performance but have no concrete way to determine where the bottleneck is. Have been relatively successful throwing darts at this point but I'm beyond that now :) PS: Screensaver is hosted at CodePlex if you want to look at the source and missed the link above. Edit: My RenderOptions darts... // NOTE: Grasping at straws here ;-) RenderOptions.SetBitmapScalingMode(newHeart, BitmapScalingMode.LowQuality); RenderOptions.SetCachingHint(newHeart, CachingHint.Cache); RenderOptions.SetEdgeMode(newHeart, EdgeMode.Aliased); I threw those a little while back and didn't see much difference (not sure if the bitmap scaling even comes into play). Really wish I could get profiling working to know where I should try to optimize. For now I assume there is some overhead in creating a new HeartVisual and the DrawingVisual contained inside. Maybe if I reset and reused the hearts (tossed them in a queue once they completed or something) I'd see an improvement. Shrug Throwing darts while blindfolder is always fun.

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  • Rx Reactive extensions: Unit testing with FromAsyncPattern

    - by Andrew Anderson
    The Reactive Extensions have a sexy little hook to simplify calling async methods: var func = Observable.FromAsyncPattern<InType, OutType>( myWcfService.BeginDoStuff, myWcfService.EndDoStuff); func(inData).ObserveOnDispatcher().Subscribe(x => Foo(x)); I am using this in an WPF project, and it works great at runtime. Unfortunately, when trying to unit test methods that use this technique I am experiencing random failures. ~3 out of every five executions of a test that contain this code fails. Here is a sample test (implemented using a Rhino/unity auto-mocking container): [TestMethod()] public void SomeTest() { // arrange var container = GetAutoMockingContainer(); container.Resolve<IMyWcfServiceClient>() .Expect(x => x.BeginDoStuff(null, null, null)) .IgnoreArguments() .Do( new Func<Specification, AsyncCallback, object, IAsyncResult>((inData, asyncCallback, state) => { return new CompletedAsyncResult(asyncCallback, state); })); container.Resolve<IRepositoryServiceClient>() .Expect(x => x.EndRetrieveAttributeDefinitionsForSorting(null)) .IgnoreArguments() .Do( new Func<IAsyncResult, OutData>((ar) => { return someMockData; })); // act var target = CreateTestSubject(container); target.DoMethodThatInvokesService(); // Run the dispatcher for everything over background priority Dispatcher.CurrentDispatcher.Invoke(DispatcherPriority.Background, new Action(() => { })); // assert Assert.IsTrue(my operation ran as expected); } The problem that I see is that the code that I specified to run when the async action completed (in this case, Foo(x)), is never called. I can verify this by setting breakpoints in Foo and observing that they are never reached. Further, I can force a long delay after calling DoMethodThatInvokesService (which kicks off the async call), and the code is still never run. I do know that the lines of code invoking the Rx framework were called. Other things I've tried: I have attempted to modify the second last line according to the suggestions here: Reactive Extensions Rx - unit testing something with ObserveOnDispatcher No love. I have added .Take(1) to the Rx code as follows: func(inData).ObserveOnDispatcher().Take(1).Subscribe(x = Foo(x)); This improved my failure rate to something like 1 in 5, but they still occurred. I have rewritten the Rx code to use the plain jane Async pattern. This works, however my developer ego really would love to use Rx instead of boring old begin/end. In the end I do have a work around in hand (i.e. don't use Rx), however I feel that it is not ideal. If anyone has ran into this problem in the past and found a solution, I'd dearly love to hear it.

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  • Interfacing Android Nexus One with Arduino + BlueSmirf

    - by efgomez
    I'm a bit new to all of this, so bear with me - I'd really appreciate your help. I am trying to link the Android Nexus One with an arduino (Duemilanove) that is connected to a BlueSmirf. I have a program that is simply outputting the string "Hello Bluetooth" to whatever device the BlueSmirf is connected to. Here is the Arduino program: void setup(){ Serial.begin(115200); int i; } void loop(){Serial.print("Hello Bluetooth!"); delay(1000); } One my computer BT terminal I can see the message and connect no problem. The trouble is with my android code. I can connect to the device with android, but when I look at the log it is not displaying "Hello Bluetooth". Here is the debug log: 04-09 16:27:49.022: ERROR/BTArduino(17288): FireFly-2583 connected 04-09 16:27:49.022: ERROR/BTArduino(17288): STARTING TO CONNECT THE SOCKET 04-09 16:27:55.705: ERROR/BTArduino(17288): Received: 16 04-09 16:27:56.702: ERROR/BTArduino(17288): Received: 1 04-09 16:27:56.712: ERROR/BTArduino(17288): Received: 15 04-09 16:27:57.702: ERROR/BTArduino(17288): Received: 1 04-09 16:27:57.702: ERROR/BTArduino(17288): Received: 15 04-09 16:27:58.704: ERROR/BTArduino(17288): Received: 1 04-09 16:27:58.704: ERROR/BTArduino(17288): Received: 15 ect... Here is the code, I'm trying to put only the relative code but if you need more please let me know: private class ConnectThread extends Thread { private final BluetoothSocket mySocket; private final BluetoothDevice myDevice; public ConnectThread(BluetoothDevice device) { myDevice = device; BluetoothSocket tmp = null; try { tmp = device.createRfcommSocketToServiceRecord(MY_UUID); } catch (IOException e) { Log.e(TAG, "CONNECTION IN THREAD DIDNT WORK"); } mySocket = tmp; } public void run() { Log.e(TAG, "STARTING TO CONNECT THE SOCKET"); InputStream inStream = null; boolean run = false; //...More Connection code here... The more relative code is here: byte[] buffer = new byte[1024]; int bytes; // handle Connection try { inStream = mySocket.getInputStream(); while (run) { try { bytes = inStream.read(buffer); Log.e(TAG, "Received: " + bytes); } catch (IOException e3) { Log.e(TAG, "disconnected"); } } I am reading bytes = inStream.read(buffer). I know bytes is an integer, so I tried sending integers over bluetooth because "bytes" was an integer but it still didn't make sense. It almost appears that is sending incorrect baud rate. Could this be true? Any help would be appreciated. Thank you very much.

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  • Voice Recognition Connection problem

    - by user244190
    I,m trying to work through and test a Voice Recognition example based on the VoiceRecognition.java example at http://developer.android.com/resources/samples/ApiDemos/src/com/example/android/apis/app/VoiceRecognition.html but when click on the button to create the activity, I get a dialog that says Connection problem. My Manifest file is using the Internet Permission, and I understand it passes the to the Google Servers. Do I need to do anything else to use this. Code below UPDATE: Ok, I was able to replace my emulator image with one from HTC that appears to come with Google Voice Search, however now when I run from the emulator, i'm getting an Audio Problem message with Speak Again or Cancel buttons. It appears to make it back to the onActivityResult(), but the resultCode is 0. Here is the LogCat output: 03-07 20:21:25.396: INFO/ActivityManager(578): Starting activity: Intent { action=android.speech.action.RECOGNIZE_SPEECH comp={com.google.android.voicesearch/com.google.android.voicesearch.RecognitionActivity} (has extras) } 03-07 20:21:25.406: WARN/ActivityManager(578): Activity is launching as a new task, so cancelling activity result. 03-07 20:21:25.968: WARN/ActivityManager(578): Activity pause timeout for HistoryRecord{434f7850 {com.ikonicsoft.mileagegenie/com.ikonicsoft.mileagegenie.MileageGenie}} 03-07 20:21:26.206: WARN/AudioHardwareInterface(554): getInputBufferSize bad sampling rate: 16000 03-07 20:21:26.256: ERROR/AudioRecord(819): Recording parameters are not supported: sampleRate 16000, channelCount 1, format 1 03-07 20:21:26.696: INFO/ActivityManager(578): Displayed activity com.google.android.voicesearch/.RecognitionActivity: 1295 ms 03-07 20:21:29.890: DEBUG/dalvikvm(806): threadid=3: still suspended after undo (s=1 d=1) 03-07 20:21:29.896: INFO/dalvikvm(806): Uncaught exception thrown by finalizer (will be discarded): 03-07 20:21:29.896: INFO/dalvikvm(806): Ljava/lang/IllegalStateException;: Finalizing cursor android.database.sqlite.SQLiteCursor@435d3c50 on ml_trackdata that has not been deactivated or closed 03-07 20:21:29.896: INFO/dalvikvm(806): at android.database.sqlite.SQLiteCursor.finalize(SQLiteCursor.java:596) 03-07 20:21:29.896: INFO/dalvikvm(806): at dalvik.system.NativeStart.run(Native Method) 03-07 20:21:31.468: DEBUG/dalvikvm(806): threadid=5: still suspended after undo (s=1 d=1) 03-07 20:21:32.436: WARN/IInputConnectionWrapper(806): showStatusIcon on inactive InputConnection I,m still not sure why I,m getting the Connect problem on the Droid. I can use Voice Search ok. I also tried clearing the cache, and data as described in some posts, butstill not working?? /** * Fire an intent to start the speech recognition activity. */ private void startVoiceRecognitionActivity() { Intent intent = new Intent(RecognizerIntent.ACTION_RECOGNIZE_SPEECH); intent.putExtra(RecognizerIntent.EXTRA_LANGUAGE_MODEL, RecognizerIntent.LANGUAGE_MODEL_FREE_FORM); intent.putExtra(RecognizerIntent.EXTRA_PROMPT, "Speech recognition demo"); startActivityForResult(intent, VOICE_RECOGNITION_REQUEST_CODE); } /** * Handle the results from the recognition activity. */ @Override protected void onActivityResult(int requestCode, int resultCode, Intent data) { if (requestCode == VOICE_RECOGNITION_REQUEST_CODE && resultCode == RESULT_OK) { // Fill the list view with the strings the recognizer thought it could have heard ArrayList<String> matches = data.getStringArrayListExtra( RecognizerIntent.EXTRA_RESULTS); mList.setAdapter(new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, matches)); } super.onActivityResult(requestCode, resultCode, data); }

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  • OCR an RSA key fob (security token)

    - by user130582
    I put together a quick WinForm/embedded IE browser control which logs into our company's bank website each morning and scrapes/exports the desired deposit information (the bank is a smallish regional bank). Since we have a few dozen "pseudoaccounts" that draw from the same master account, this actually takes 10-15 minutes to retrieve. Anyway, the only problem is that our business bank account reuires an RSA security token (http://www.rsa.com/node.aspx?id=1156)--if you are not familiar, it is a small device which shows a random 6 digit number every 15(?) seconds, so I have to prompt for this value before starting. This is on top of the website's login based security model, so even if you create a read-only account that can't do anything, you still have to put the RSA number in. We have 5 of these tokens for different people in the company. From our perspective this is nusiance security. I was joking about using a web camera to OCR the digits from the key fob so they didn't have to type it in -- mainly so that the scraping/export would be done before anyone arrives in the morning. Well, they asked if I could really do it. So now I ask you, how hard (how many hours) do you think it would take to OCR these digits reliably from a JPEG image produced by the camera? I already know I can get the JPEG easily. I think you get 3 tries to log in, so it really needs to hit a 99% accuracy rate. I could work on this on my off time, but they don't want me to put more than a few hours into it, so I want to leverage as much existing code as possible. This is a 7-segment display (like an alarm clock) so it's not exactly text that an OCR package would be used to seeing. Also--there is a countdown timer on the side of the display; typically when it is down to 1 bar, you wait until the next number appears and it starts over at 5 bars (like signal strength on your cell phone). So this would need to be OCRd as well but it is not text. Anyway the more I think about it as I type this, the less convinced I am that I can truly get this right, so maybe I should just work on it in my spare time?

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  • Using Artificial Intelligence (AI) to predict Stock Prices

    - by akaphenom
    Given a set of datavery similar to the Motley Fool CAPS system, where individual users enter BUY and SELL recommendations on various equities. What I would like to do is show each recommendation and I guess some how rate (1-5) as to whether it was good predictor<5 (ie corellation coeffient = 1) of the future stock price (or eps or whatever) or a horrible predictor (ie corellation coeffient = -1) or somewhere inbetween. Each recommendation is tagged to a particular user, so that can be tracked over time. I can also track market direction (bullish / bearish) based off of something like sp500 price. The components I think that would make sense in the model would be: user direction (long/short) market direction sector of stock The thought is that some users are better in bull markets than bear (and vice versa), and some are better at shorts than longs- and then a cobination the above. I can automatically tag the market direction and sector (based off the market at the time and the equity being recommended). The thought is that I could present a series of screens and allow me to rank each individual recommendation by displaying available data absolute, market and sector out performance for a specfic time period out. I would follow a detailed list for ranking the stocks so that the ranking is as objective as possible. My assumtion is that a single user is right no more than 57% of the time - but who knows. I could load the system and say "Lets rank the recommendation as a predictor of stock value 90 days forward"; and that would represent a very explicit set of rankings. NOW here is the crux - I want to create some sort of machine learning algorithm that can identify patterns over a series of time so that as recommendations stream into the application we maintain a ranking of that stock (ie. similar to correlation coeeficient) as to the likelihood of that recommendation (in addition to the past series of recommendations ) will affect the price. Now here is the super crux. I have never taken an AI class / read an AI book / never mind specific to machine learning. So I cam looking for guidance - sample or description of a similar system I could adapt. Place to look for info or any general help. Or even push me in the right direction to get started... My hope is to implment this with F# and be able to impress my friends with a new skillset in F# with an implementation of machine learnign and potentially something (application / source) I can include in a tech portfolio or blog space; Thank you for any advice in advance.

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  • Is this a good way to do a game loop for an iPhone game?

    - by Danny Tuppeny
    Hi all, I'm new to iPhone dev, but trying to build a 2D game. I was following a book, but the game loop it created basically said: function gameLoop update() render() sleep(1/30th second) gameLoop The reasoning was that this would run at 30fps. However, this seemed a little mental, because if my frame took 1/30th second, then it would run at 15fps (since it'll spend as much time sleeping as updating). So, I did some digging and found the CADisplayLink class which would sync calls to my gameLoop function to the refresh rate (or a fraction of it). I can't find many samples of it, so I'm posting here for a code review :-) It seems to work as expected, and it includes passing the elapsed (frame) time into the Update method so my logic can be framerate-independant (however I can't actually find in the docs what CADisplayLink would do if my frame took more than its allowed time to run - I'm hoping it just does its best to catch up, and doesn't crash!). // // GameAppDelegate.m // // Created by Danny Tuppeny on 10/03/2010. // Copyright Danny Tuppeny 2010. All rights reserved. // #import "GameAppDelegate.h" #import "GameViewController.h" #import "GameStates/gsSplash.h" @implementation GameAppDelegate @synthesize window; @synthesize viewController; - (void) applicationDidFinishLaunching:(UIApplication *)application { // Create an instance of the first GameState (Splash Screen) [self doStateChange:[gsSplash class]]; // Set up the game loop displayLink = [CADisplayLink displayLinkWithTarget:self selector:@selector(gameLoop)]; [displayLink setFrameInterval:2]; [displayLink addToRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode]; } - (void) gameLoop { // Calculate how long has passed since the previous frame CFTimeInterval currentFrameTime = [displayLink timestamp]; CFTimeInterval elapsed = 0; // For the first frame, we want to pass 0 (since we haven't elapsed any time), so only // calculate this in the case where we're not the first frame if (lastFrameTime != 0) { elapsed = currentFrameTime - lastFrameTime; } // Keep track of this frames time (so we can calculate this next time) lastFrameTime = currentFrameTime; NSLog([NSString stringWithFormat:@"%f", elapsed]); // Call update, passing the elapsed time in [((GameState*)viewController.view) Update:elapsed]; } - (void) doStateChange:(Class)state { // Remove the previous GameState if (viewController.view != nil) { [viewController.view removeFromSuperview]; [viewController.view release]; } // Create the new GameState viewController.view = [[state alloc] initWithFrame:CGRectMake(0, 0, IPHONE_WIDTH, IPHONE_HEIGHT) andManager:self]; // Now set as visible [window addSubview:viewController.view]; [window makeKeyAndVisible]; } - (void) dealloc { [viewController release]; [window release]; [super dealloc]; } @end Any feedback would be appreciated :-) PS. Bonus points if you can tell me why all the books use "viewController.view" but for everything else seem to use "[object name]" format. Why not [viewController view]?

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  • How to quickly acquire and process real time screen output

    - by Akusete
    I am trying to write a program to play a full screen PC game for fun (as an experiment in Computer Vision and Artificial Intelligence). For this experiment I am assuming the game has no underlying API for AI players (nor is the source available) so I intend to process the visual information rendered by the game on the screen. The game runs in full screen mode on a win32 system (direct-X I assume). Currently I am using the win32 functions #include <windows.h> #include <cvaux.h> class Screen { public: HWND windowHandle; HDC windowContext; HBITMAP buffer; HDC bufferContext; CvSize size; uchar* bytes; int channels; Screen () { windowHandle = GetDesktopWindow(); windowContext = GetWindowDC (windowHandle); size = cvSize (GetDeviceCaps (windowContext, HORZRES), GetDeviceCaps (windowContext, VERTRES)); buffer = CreateCompatibleBitmap (windowContext, size.width, size.height); bufferContext = CreateCompatibleDC (windowContext); SelectObject (bufferContext, buffer); channels = 4; bytes = new uchar[size.width * size.height * channels]; } ~Screen () { ReleaseDC(windowHandle, windowContext); DeleteDC(bufferContext); DeleteObject(buffer); delete[] bytes; } void CaptureScreen (IplImage* img) { BitBlt(bufferContext, 0, 0, size.width, size.height, windowContext, 0, 0, SRCCOPY); int n = size.width * size.height; int imgChannels = img->nChannels; GetBitmapBits (buffer, n * channels, bytes); uchar* src = bytes; uchar* dest = (uchar*) img->imageData; uchar* end = dest + n * imgChannels; while (dest < end) { dest[0] = src[0]; dest[1] = src[1]; dest[2] = src[2]; dest += imgChannels; src += channels; } } The rate at which I can process frames using this approach is much to slow. Is there a better way to acquire screen frames?

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  • Drawing performance with CGImageCreateWithJPEGDataProvider?

    - by Rnegi
    I've actually curious about this for the iPhone. I am getting an MJPEG stream from a server and trying to render it natively on the iphone (without the use of safari class). Reasons for this is because the safari class while CAN render MJPEG natively, does not do so at the framerate I would like. So I tried drawing it natively, but I've come up with performance issues, namely a syncing issue between what I'm getting from the server and what I am able to draw onto the screen of the phone. (There should be a little lag, but the drift gets really bad, which is what I want to avoid). So I have a connection set up to my server and I do get the JPEGS. It's just data I insert into a NSMutableArray buffer CFMutableDataRef _t_data_ref = (CFMutableDataRef)[_buffer_array objectAtIndex:0]; //CGDataProviderRef imgDataProvider = CGDataProviderCreateWithCFData (_cf_buffer_data); CGDataProviderRef imgDataProvider = CGDataProviderCreateWithCFData(_t_data_ref); CGImageRef image = CGImageCreateWithJPEGDataProvider(imgDataProvider, NULL, true, kCGRenderingIntentDefault); CGImageRef imgRef = image; CGContextDrawImage(context, CGRectMake(0, 17, 380, 285), imgRef); CGImageRelease(image); CGDataProviderRelease(imgDataProvider); please note this is the gist of my code, but it should summarize what I am trying to accomplish with regards to drawing. Also in order to get the framerate in sync, I had to detach a separate thread that sleeps X seconds and calls [self setNeedsDisplay]. NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; // Top-level pool while(1) { //[NSThread sleepForTimeInterval:TIMER_REFRESH_VALUE]; //sleep(unsigned int ); usleep(MICRO_REFRESH_VALUE); if ([_buffer_array count] > 10) { //NSLog(@"stuff %d", [_buffer_array count]); //[self setNeedsDisplay]; [self performSelectorOnMainThread:@selector(setNeedsDisplay) withObject:nil waitUntilDone:NO]; } } [pool release]; // Release the objects in the pool. My buffer of jpeg data actually fills up quite quick, but I can't seem to actually consume what i'm getting at the same rate, actually much slower. Are there any documents that can describe what kind of performance tuning I can do to make it go faster when rendering the JPEG to the screen? Or am I kind of stuck here? Thanks!

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  • How do I prevent the concurrent execution of a javascript function?

    - by RyanV
    I am making a ticker similar to the "From the AP" one at The Huffington Post, using jQuery. The ticker rotates through a ul, either by user command (clicking an arrow) or by an auto-scroll. Each list-item is display:none by default. It is revealed by the addition of a "showHeadline" class which is display:list-item. HTML for the UL Looks like this: <ul class="news" id="news"> <li class="tickerTitle showHeadline">Test Entry</li> <li class="tickerTitle">Test Entry2</li> <li class="tickerTitle">Test Entry3</li> </ul> When the user clicks the right arrow, or the auto-scroll setTimeout goes off, it runs a tickForward() function: function tickForward(){ var $active = $('#news li.showHeadline'); var $next = $active.next(); if($next.length==0) $next = $('#news li:first'); $active.stop(true, true); $active.fadeOut('slow', function() {$active.removeClass('showHeadline');}); setTimeout(function(){$next.fadeIn('slow', function(){$next.addClass('showHeadline');})}, 1000); if(isPaused == true){ } else{ startScroll() } }; This is heavily inspired by Jon Raasch's A Simple jQuery Slideshow. Basically, find what's visible, what should be visible next, make the visible thing fade and remove the class that marks it as visible, then fade in the next thing and add the class that makes it visible. Now, everything is hunky-dory if the auto-scroll is running, kicking off tickForward() once every three seconds. But if the user clicks the arrow button repeatedly, it creates two negative conditions: Rather than advance quickly through the list for just the number of clicks made, it continues scrolling at a faster-than-normal rate indefinitely. It can produce a situation where two (or more) list items are given the .showHeadline class, so there's overlap on the list. I can see these happening (especially #2) because the tickForward() function can run concurrently with itself, producing different sets of $active and $next. So I think my question is: What would be the best way to prevent concurrent execution of the tickForward() method? Some things I have tried or considered: Setting a Flag: When tickForward() runs, it sets an isRunning flag to true, and sets it back to false right before it ends. The logic for the event handler is set to only call tickForward() if isRunning is false. I tried a simple implementation of this, and isRunning never appeared to be changed. The jQuery queue(): I think it would be useful to queue up the tickForward() commands, so if you clicked it five times quickly, it would still run as commanded but wouldn't run concurrently. However, in my cursory reading on the subject, it appears that a queue has to be attached to the object its queue applies to, and since my tickForward() method affects multiple lis, I don't know where I'd attach it.

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  • Why does PostgresQL query performance drop over time, but restored when rebuilding index

    - by Jim Rush
    According to this page in the manual, indexes don't need to be maintained. However, we are running with a PostgresQL table that has a continuous rate of updates, deletes and inserts that over time (a few days) sees a significant query degradation. If we delete and recreate the index, query performance is restored. We are using out of the box settings. The table in our test is currently starting out empty and grows to half a million rows. It has a fairly large row (lots of text fields). We are search is based of an index, not the primary key (I've confirmed the index is being used, at least under normal conditions) The table is being used as a persistent store for a single process. Using PostgresQL on Windows with a Java client I'm willing to give up insert and update performance to keep up the query performance. We are considering rearchitecting the application so that data is spread across various dynamic tables in a manner that allows us to drop and rebuild indexes periodically without impacting the application. However, as always, there is a time crunch to get this to work and I suspect we are missing something basic in our configuration or usage. We have considered forcing vacuuming and rebuild to run at certain times, but I suspect the locking period for such an action would cause our query to block. This may be an option, but there are some real-time (windows of 3-5 seconds) implications that require other changes in our code. Additional information: Table and index CREATE TABLE icl_contacts ( id bigint NOT NULL, campaignfqname character varying(255) NOT NULL, currentstate character(16) NOT NULL, xmlscheduledtime character(23) NOT NULL, ... 25 or so other fields. Most of them fixed or varying character fiel ... CONSTRAINT icl_contacts_pkey PRIMARY KEY (id) ) WITH (OIDS=FALSE); ALTER TABLE icl_contacts OWNER TO postgres; CREATE INDEX icl_contacts_idx ON icl_contacts USING btree (xmlscheduledtime, currentstate, campaignfqname); Analyze: Limit (cost=0.00..3792.10 rows=750 width=32) (actual time=48.922..59.601 rows=750 loops=1) - Index Scan using icl_contacts_idx on icl_contacts (cost=0.00..934580.47 rows=184841 width=32) (actual time=48.909..55.961 rows=750 loops=1) Index Cond: ((xmlscheduledtime < '2010-05-20T13:00:00.000'::bpchar) AND (currentstate = 'SCHEDULED'::bpchar) AND ((campaignfqname)::text = '.main.ee45692a-6113-43cb-9257-7b6bf65f0c3e'::text)) And, yes, I am aware there there are a variety of things we could do to normalize and improve the design of this table. Some of these options may be available to us. My focus in this question is about understanding how PostgresQL is managing the index and query over time (understand why, not just fix). If it were to be done over or significantly refactored, there would be a lot of changes.

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  • Non-linear regression models in PostgreSQL using R

    - by Dave Jarvis
    Background I have climate data (temperature, precipitation, snow depth) for all of Canada between 1900 and 2009. I have written a basic website and the simplest page allows users to choose category and city. They then get back a very simple report (without the parameters and calculations section): The primary purpose of the web application is to provide a simple user interface so that the general public can explore the data in meaningful ways. (A list of numbers is not meaningful to the general public, nor is a website that provides too many inputs.) The secondary purpose of the application is to provide climatologists and other scientists with deeper ways to view the data. (Using too many inputs, of course.) Tool Set The database is PostgreSQL with R (mostly) installed. The reports are written using iReport and generated using JasperReports. Poor Model Choice Currently, a linear regression model is applied against annual averages of daily data. The linear regression model is calculated within a PostgreSQL function as follows: SELECT regr_slope( amount, year_taken ), regr_intercept( amount, year_taken ), corr( amount, year_taken ) FROM temp_regression INTO STRICT slope, intercept, correlation; The results are returned to JasperReports using: SELECT year_taken, amount, year_taken * slope + intercept, slope, intercept, correlation, total_measurements INTO result; JasperReports calls into PostgreSQL using the following parameterized analysis function: SELECT year_taken, amount, measurements, regression_line, slope, intercept, correlation, total_measurements, execute_time FROM climate.analysis( $P{CityId}, $P{Elevation1}, $P{Elevation2}, $P{Radius}, $P{CategoryId}, $P{Year1}, $P{Year2} ) ORDER BY year_taken This is not an optimal solution because it gives the false impression that the climate is changing at a slow, but steady rate. Questions Using functions that take two parameters (e.g., year [X] and amount [Y]), such as PostgreSQL's regr_slope: What is a better regression model to apply? What CPAN-R packages provide such models? (Installable, ideally, using apt-get.) How can the R functions be called within a PostgreSQL function? If no such functions exist: What parameters should I try to obtain for functions that will produce the desired fit? How would you recommend showing the best fit curve? Keep in mind that this is a web app for use by the general public. If the only way to analyse the data is from an R shell, then the purpose has been defeated. (I know this is not the case for most R functions I have looked at so far.) Thank you!

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  • Correlated SQL Join Query from multiple tables

    - by SooDesuNe
    I have two tables like the ones below. I need to find what exchangeRate was in effect at the dateOfPurchase. I've tried some correlated sub queries, but I'm having difficulty getting the correlated record to be used in the sub queries. I expect a solution will need to follow this basic outline: SELECT only the exchangeRates for the applicable countryCode From 1. SELECT the newest exchangeRate less than the dateOfPurchase Fill in the query table with all the fields from 2. and the purchasesTable. My Tables: purchasesTable: > dateOfPurchase | costOfPurchase | countryOfPurchase > 29-March-2010 | 20.00 | EUR > 29-March-2010 | 3000 | JPN > 30-March-2010 | 50.00 | EUR > 30-March-2010 | 3000 | JPN > 30-March-2010 | 2000 | JPN > 31-March-2010 | 100.00 | EUR > 31-March-2010 | 125.00 | EUR > 31-March-2010 | 2000 | JPN > 31-March-2010 | 2400 | JPN costOfPurchase is in whatever the local currency is for a given countryCode exchangeRateTable > effectiveDate | countryCode | exchangeRate > 29-March-2010 | JPN | 90 > 29-March-2010 | EUR | 1.75 > 30-March-2010 | JPN | 92 > 31-March-2010 | JPN | 91 The results of the query that I'm looking for: > dateOfPurchase | costOfPurchase | countryOfPurchase | exchangeRate > 29-March-2010 | 20.00 | EUR | 1.75 > 29-March-2010 | 3000 | JPN | 90 > 30-March-2010 | 50.00 | EUR | 1.75 > 30-March-2010 | 3000 | JPN | 92 > 30-March-2010 | 2000 | JPN | 92 > 31-March-2010 | 100.00 | EUR | 1.75 > 31-March-2010 | 125.00 | EUR | 1.75 > 31-March-2010 | 2000 | JPN | 91 > 31-March-2010 | 2400 | JPN | 91 So for example in the results, the exchange rate, in effect for EUR on 31-March was 1.75. I'm using Access, but a MySQL answer would be fine too. UPDATE: Modification to Allan's answer: SELECT dateOfPurchase, costOfPurchase, countryOfPurchase, exchangeRate FROM purchasesTable p LEFT OUTER JOIN (SELECT e1.exchangeRate, e1.countryCode, e1.effectiveDate, min(e2.effectiveDate) AS enddate FROM exchangeRateTable e1 LEFT OUTER JOIN exchangeRateTable e2 ON e1.effectiveDate < e2.effectiveDate AND e1.countryCode = e2.countryCode GROUP BY e1.exchangeRate, e1.countryCode, e1.effectiveDate) e ON p.dateOfPurchase >= e.effectiveDate AND (p.dateOfPurchase < e.enddate OR e.enddate is null) AND p.countryOfPurchase = e.countryCode I had to make a couple small changes.

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  • Cant get flexigrid to work in Jquery Tools Tab

    - by John
    Im fairly new to jquery and Im using jquery tools for tabs. I am wanting in one of the tabs to show flexigrid, but when I try to do this flexigrid does not show up, its just blank. If I setup flexigrid in a stand alone page outside the tab it works just fine. Below is the code that isnt working. Again Im new so please go easy! <ul class="css-tabs"> <li><a href="#details">Account Details</a></li> <li><a href="#accounts">Sub Accounts</a></li> <li><a href="#groups">Groups</a></li> <li><a href="#support">Tickets</a></li> </ul> <div class="css-panes"> <div>Tab 1</div> <div><table id="flex1" style="display:none"></table></div> <div>Tab 3</div> <div>Tab 4</div> </div> <script> $(function() { $("ul.css-tabs").tabs("div.css-panes > div").history(); }); $('.flexme1').flexigrid(); $('.flexme2').flexigrid({height:'auto',striped:false}); $("#flex1").flexigrid ( { url: '/accounts_list.php', dataType: 'json', colModel : [ {display: 'ID', name : 'id', width : 45, sortable : true, align: 'center'}, {display: 'Username', name : 'username', width : 120, sortable : true, align: 'left'}, {display: 'Display Name', name : 'displayname', width : 150, sortable : true, align: 'left'}, {display: 'Limit', name : 'accounts', width : 50, sortable : true, align: 'center'}, {display: 'Rate', name : 'charge', width : 50, sortable : true, align: 'center'}, {display: 'Subs', name : 'subcount', width : 50, sortable : true, align: 'center'} ], searchitems : [ {display: 'ID', name : 'id'}, {display: 'Username', name : 'username', isdefault: true}, {display: 'Display Name', name : 'displayname'} ], sortname: "id", sortorder: "desc", usepager: true, singleSelect: true, title: 'Test', useRp: true, rp: 20, showTableToggleBtn: false, width: 500, height: 250 }); </script>

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  • Tunnel over HTTPS

    - by ephemient
    At my workplace, the traffic blocker/firewall has been getting progressively worse. I can't connect to my home machine on port 22, and lack of ssh access makes me sad. I was previously able to use SSH by moving it to port 5050, but I think some recent filters now treat this traffic as IM and redirect it through another proxy, maybe. That's my best guess; in any case, my ssh connections now terminate before I get to log in. These days I've been using Ajaxterm over HTTPS, as port 443 is still unmolested, but this is far from ideal. (Sucky terminal emulation, lack of port forwarding, my browser leaks memory at an amazing rate...) I tried setting up mod_proxy_connect on top of mod_ssl, with the idea that I could send a CONNECT localhost:22 HTTP/1.1 request through HTTPS, and then I'd be all set. Sadly, this seems to not work; the HTTPS connection works, up until I finish sending my request; then SSL craps out. It appears as though mod_proxy_connect takes over the whole connection instead of continuing to pipe through mod_ssl, confusing the heck out of the HTTPS client. Is there a way to get this to work? I don't want to do this over plain HTTP, for several reasons: Leaving a big fat open proxy like that just stinks A big fat open proxy is not good over HTTPS either, but with authentication required it feels fine to me HTTP goes through a proxy -- I'm not too concerned about my traffic being sniffed, as it's ssh that'll be going "plaintext" through the tunnel -- but it's a lot more likely to be mangled than HTTPS, which fundamentally cannot be proxied Requirements: Must work over port 443, without disturbing other HTTPS traffic (i.e. I can't just put the ssh server on port 443, because I would no longer be able to serve pages over HTTPS) I have or can write a simple port forwarder client that runs under Windows (or Cygwin) Edit DAG: Tunnelling SSH over HTTP(S) has been pointed out to me, but it doesn't help: at the end of the article, they mention Bug 29744 - CONNECT does not work over existing SSL connection preventing tunnelling over HTTPS, exactly the problem I was running into. At this point, I am probably looking at some CGI script, but I don't want to list that as a requirement if there's better solutions available.

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  • Alternatives to requiring users to register for an account?

    - by jamieb
    I'm working on a side project to build a new web app idea of mine. For the sake of discussion, let's say this app displays a random photograph of a famous work of art. On a scale of 1 to 5, users are asked to rate how well they like each piece of art, and then are shown the next photo. Eventually, the app is able to get an sense of the person's style and is able to recommend artwork that he/she may find pleasing. The whole concept is similar to Netflix. I understand how to do all the preference matching logic (although not as sophisticated as Netflix). But I'd like to find a way to do this without requiring that users create an account first. This is a novelty website that a typical user might use only a handful of times. Requiring registration is overkill and will likely drastically reduce it's utility. I'd like to allow people to begin rating artwork within five seconds of their initial pageview, yet maintain the integrity of the voting (since recommendations are predicated on how other people have rated the various pieces of artwork). Can it be done? Some ideas: OpenID. The perfect solution except for the fact that it's not wildly used and my target audience isn't the most technically adept demographic. Text message. User inputs phone number and is texted a four digit code to key into the web app. Quick, easy, and great way to limit abuse. However, privacy concerns abound... people are probably even less likely to give me their phone number than their email address. Facebook login. I personally don't have a Facebook account due to privacy concerns. And I'd really hate to support such a proprietary platform. Hash code/Bookmark. Vistor's initial pageview generates a 5 or 6 digit alphanumeric code that is embedded in each subsequent URL. They can bookmark any page to save their state. Good: Very simple system that doesn't require any user action. Bad: Very easy to stuff the ballot box, might be difficult to account for users sharing the link containing their ID code via email or social networking sites.

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  • How effective are technical test(s) and is it necessary?

    - by The Elite Gentleman
    Hi everyone, I recently took a Java technical test (for a company who wanted are looking for senior java developers) and, funny enough, I only realised the technical terms of what I've been doing all along after I've written the test. I'm not too IT jargon when it comes to development but I can pretty much code and create solutions unaware that I'm using design pattern (or the specifics of that design pattern) or technology. I learned things such as JMS, Frameworks, etc. while programming at home and having to google stuff online to problems I have. Others e.g. IoC, Surrogates in Databases, etc., I have used extensively without knowing that it had a name for it. Do you think that these technical test are effective and why? What interesting questions did you find that boggled your brains out while the clock kept ticking? Seeing that IT is vastly evolving at a rapid rate, do we have to constantly be updated with new terms that comes out? Some questions I was asked : What object oriented principle is violated by this architectural mechanism for dot notation? Is indexing tables effective for range query or point query search? What is ThreadLocal and what is it used for? Method overloading vs Method overriding. What is the difference between the 2? What is dynamic binding? Now, imagine my poor head trying to understand these jargons (considering I use it almost everyday) PS The question was not a programming question, where you have a problem and write code to solve it. Rather, a thinking type question and you write answers (against the clock). Update I clearly didn't come out clearly as I should have. There are those that are technically "book smart" but with very little hands-on experience and vice versa. So, the question (in connection to what I've asked) is that are these technical test seeking "book smart" people or people with lots of hands-on experience (some who are not that well clued up with too much book-smart jargons). How effective is it then, for companies to look for developers if most of the questions are too terminology-centric? (if that's the correct term, :))

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  • Core-Data + AFNetworking + UI Updating (Responsiveness)

    - by Mustafa
    Here's the scenario: I'm writing a DownloadManager, that allows the user to download, pause, cancel, download all, and pause all. The DownloadManager is a singleton, and uses AFNetworking to download files. It has it's own private managed object context, so that user can freely use other parts of the application (by adding, editing, deleting) core-data objects. I have a core-data entity DownloadInfo that stores the download information i.e. fileURL, fileSize, bytesRead, etc. The DownloadManager updates the download progress in DownloadInfo (one for each file). I have a DownloadManagerViewController which uses NSFetchedResultsController to show the download status to the user. This download view controller is using the main managed object context. Now let's say that I have 20 files in the download queue. And let's say that only 3 concurrent downloads are allowed. The download manager should download the file, and show the download progress. Problem: The DownloadInfo objects are being updated by the DownloadManager at a very high rate. The DownloadManagerViewController (responsible for showing the download progress) is updating the list using NSFetchedResultsControllerDelegate methods. The result is that a lot is happening in the main queue and application has very poor responsiveness. How can I fix this? How can I make the application responsive, while showing the download progress? I don't know how else to communicate that the download status between DownloadManager and DownloadManagerViewController. Is there another/ a better way to do this? I don't want to use main managed object context in my DownloadManager, for reasons mentioned above. Note, that the DownloadManager is using AFNetworking which is handling the requests asynchronously, but eventually the DownloadInfo objects are updated in the main thread (as a result of the callback methods). Maybe there's a way to handle the downloads and status update operations in a background thread? but how? How will I communicate between the main thread and the background thread i.e. how will I tell the background thread to queue another file for download? Thanks.

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  • Coldfusion Components:- The argument passed to the function is not of type numeric

    - by salim.vali
    Hi I have a simple form form.cfm:- <cfset Registr = createObject("component", "forms.Registr") /> <cfset setFoo = createObject('component','forms.Registr).putNUsr(username,password,rating) /> <form name="regFrm" action="#cgi.script_name#" method="post" onsubmit="submitform();" > <tr><td>Username:</td> <td><input type="text" name=" Username" value="#form. Username#" ></td></tr> <tr><td>Password:</td> <td><input class="" type="password" name="password" value="#form.password#" ></td></tr> <tr><td>Rate:</td> <select name="rating" > <option value="" ></option> <cfloop query="qGetReting"> <option value="#rating_id#" <cfif form. rating eq prof_id>selected</cfif> >#rating#</option> </cfloop> </select> </td> </tr> </form> Now there is this cfc called Registr.cfc in the "forms" folder which has an insert-function called 'putNUsr'the code for 'Registr.cfc' is as follows. <cfcomponent> <cffunction name="putNUsr" returntype="void" displayname="" output="no"> <cfargument name="password" type="string" required="true"> <cfargument name="rating" type="numeric" required="true"> <cfargument name="username" type="string" required="true"> <cfquery datasource="#application.xyz#" name="q_putNUsr"> insert into users (username , password , rating) values( <cfqueryparam value="#arguments. username#" cfsqltype="CF_SQL_VARCHAR" />, <cfqueryparam value="#arguments.password#" cfsqltype="CF_SQL_VARCHAR" />, <cfqueryparam value="#arguments.rating#" cfsqltype="CF_SQL_INTEGER" ) </cfquery> </cffunction> </cfcomponent> I am able to populate the DB with the data if I do not use the form field "rating" which is numeric. Else i am getting the error as follows:- The RATING argument passed to the putNUsr function is not of type numeric. If the component name is specified as a type of this argument, it is possible that either a definition file for the component cannot be found or is not accessible. KINDLY HELP -S Vali

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  • Optimizing mathematics on arrays of floats in Ada 95 with GNAT

    - by mat_geek
    Consider the bellow code. This code is supposed to be processing data at a fixed rate, in one second batches, It is part of an overal system and can't take up too much time. When running over 100 lots of 1 seconds worth of data the program takes 35 seconds (or 35%), executing this function in a loop. The test loop is timed specifically with Ada.RealTime. The data is pregenerated so the majority of the execution time is definatetly in this loop. How do I improce the code to get the processing time down to a minimum? The code will be running on an Intel Pentium-M which is a P3 with SSE2. package FF is new Ada.Numerics.Generic_Elementary_Functions(Float); N : constant Integer := 820; type A is array(1 .. N) of Float; type A3 is array(1 .. 3) of A; procedure F(state : in out A3; result : out A3; l : in A; r : in A) is s : Float; t : Float; begin for i in 1 .. N loop t := l(i) + r(i); t := t / 2.0; state(1)(i) := t; state(2)(i) := t * 0.25 + state(2)(i) * 0.75; state(3)(i) := t * 1.0 /64.0 + state(2)(i) * 63.0 /64.0; for r in 1 .. 3 loop s := state(r)(i); t := FF."**"(s, 6.0) + 14.0; if t > MAX then t := MAX; elsif t < MIN then t := MIN; end if; result(r)(i) := FF.Log(t, 2.0); end loop; end loop; end; psuedocode for testing create two arrays of 80 random A3 arrays, called ls and rs; init the state and result A3 array record the realtime time now, called last for i in 1 .. 100 loop for j in 1 .. 80 loop F(state, result, ls(j), rs(j)); end loop; end loop; record the realtime time now, called curr output the duration between curr and last

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  • Python/Biophysics- Trying to code a simple stochastic simulation!

    - by user359597
    Hey guys- I'm trying to figure out what to make of the following code- this is not the clear, intuitive python I've been learning. Was it written in C or something then wrapped in a python fxn? The code I wrote (not shown) is using the same math, but I couldn't figure out how to write a conditional loop. If anyone could explain/decipher/clean this up, I'd be really appreciative. I mean- is this 'good' python- or does it look funky? I'm brand new to this- but it's like the order of the fxns is messed up? I understand Gillespie's- I've successfully coded several simpler simulations. So in a nutshell- good code-(pythonic)? order? c? improvements? am i being an idiot? The code shown is the 'answer,' to the following question from a biophysics text (petri-net not shown and honestly not necessary to understand problem): "In a programming language of your choice, implement Gillespie’s First Reaction Algorithm to study the temporal behaviour of the reaction A---B in which the transition from A to B can only take place if another compound, C, is present, and where C dynamically interconverts with D, as modelled in the Petri-net below. Assume that there are 100 molecules of A, 1 of C, and no B or D present at the start of the reaction. Set kAB to 0.1 s-1 and both kCD and kDC to 1.0 s-1. Simulate the behaviour of the system over 100 s." def sim(): # Set the rate constants for all transitions kAB = 0.1 kCD = 1.0 kDC = 1.0 # Set up the initial state A = 100 B = 0 C = 1 D = 0 # Set the start and end times t = 0.0 tEnd = 100.0 print "Time\t", "Transition\t", "A\t", "B\t", "C\t", "D" # Compute the first interval transition, interval = transitionData(A, B, C, D, kAB, kCD, kDC) # Loop until the end time is exceded or no transition can fire any more while t <= tEnd and transition >= 0: print t, '\t', transition, '\t', A, '\t', B, '\t', C, '\t', D t += interval if transition == 0: A -= 1 B += 1 if transition == 1: C -= 1 D += 1 if transition == 2: C += 1 D -= 1 transition, interval = transitionData(A, B, C, D, kAB, kCD, kDC) def transitionData(A, B, C, D, kAB, kCD, kDC): """ Returns nTransition, the number of the firing transition (0: A->B, 1: C->D, 2: D->C), and interval, the interval between the time of the previous transition and that of the current one. """ RAB = kAB * A * C RCD = kCD * C RDC = kDC * D dt = [-1.0, -1.0, -1.0] if RAB > 0.0: dt[0] = -math.log(1.0 - random.random())/RAB if RCD > 0.0: dt[1] = -math.log(1.0 - random.random())/RCD if RDC > 0.0: dt[2] = -math.log(1.0 - random.random())/RDC interval = 1e36 transition = -1 for n in range(len(dt)): if dt[n] > 0.0 and dt[n] < interval: interval = dt[n] transition = n return transition, interval if __name__ == '__main__': sim()

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  • Getting problem in Java OpenCV code.

    - by Chetan
    I had successfully compile my java code in Eclipse with name FaceDetection.java... I am getting an Exception in thread "main" java.lang.NoSuchMethodError: main.... Please help me to remove this Exception.. Here is the code import java.awt.; import java.awt.event.; import java.awt.image.MemoryImageSource; import hypermedia.video.OpenCV; @SuppressWarnings("serial") public class FaceDetection extends Frame implements Runnable { /** * Main method. * @param String[] a list of user's arguments passed from the console to this program */ public static void main( String[] args ) { System.out.println( "\nOpenCV face detection sample\n" ); new FaceDetection(); } // program execution frame rate (millisecond) final int FRAME_RATE = 1000/30; OpenCV cv = null; // OpenCV Object Thread t = null; // the sample thread // the input video stream image Image frame = null; // list of all face detected area Rectangle[] squares = new Rectangle[0]; /** * Setup Frame and Object(s). */ FaceDetection() { super( "Face Detection Sample" ); // OpenCV setup cv = new OpenCV(); cv.capture( 320, 240 ); cv.cascade( OpenCV.CASCADE_FRONTALFACE_ALT ); // frame setup this.setBounds( 100, 100, cv.width, cv.height ); this.setBackground( Color.BLACK ); this.setVisible( true ); this.addKeyListener( new KeyAdapter() { public void keyReleased( KeyEvent e ) { if ( e.getKeyCode()==KeyEvent.VK_ESCAPE ) { // ESC : release OpenCV resources cv.dispose(); System.exit(0); } } } ); // start running program t = new Thread( this ); t.start(); } /** * Draw video frame and each detected faces area. */ public void paint( Graphics g ) { // draw image g.drawImage( frame, 0, 0, null ); // draw squares g.setColor( Color.RED ); for( Rectangle rect : squares ) g.drawRect( rect.x, rect.y, rect.width, rect.height ); } /** * Execute this sample. */ @SuppressWarnings("static-access") public void run() { while( t!=null && cv!=null ) { try { t.sleep( FRAME_RATE ); // grab image from video stream cv.read(); // create a new image from cv pixels data MemoryImageSource mis = new MemoryImageSource( cv.width, cv.height, cv.pixels(), 0, cv.width ); frame = createImage( mis ); // detect faces squares = cv.detect( 1.2f, 2, OpenCV.HAAR_DO_CANNY_PRUNING, 20, 20 ); // of course, repaint repaint(); } catch( InterruptedException e ) {;} } } }

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  • Web-Frameworks for Education Management Systems?

    - by Indebi
    So, I'm working on an idea and I'll go into a brief overview of that but my question is, What are some good web frameworks for this situation? I have some experience in the following languages: C# Python I have considerably more experience in C# than Python, however I am expecting to learn new things. My idea is this, a completely web-based community-oriented Education Management System that focuses on making students and teachers day-to-day lives easier. For students it will provide a centralized place for them to do homework, study for tests, and reinforce concepts learned previously in class. For teachers it will give them a centralized place to handle assignments, attendance, homework, tests, and all other major parts of classroom management. All of that, but in a community-oriented fashion. Everything a teacher does is shared and open to constructive criticism, allowing other teachers to use their assignments/tests and for students or other teachers to comment, rate and criticize their assignments. This encourages an environment of openness that will allow teacher's to focus on teaching and student's to focus on learning. And that community wouldn't be limited to one school or school-district, this system would be completely school-independent. Please note that I have no problem with hearing constructive criticism on this idea, however I would prefer if this post was more focused on my question. I have somewhat explored about the following options: Django ASP.NET Ruby on Rails Silverlight (1) I have Django installed and I played with it for a little bit, I really like how easy setting up databases are and how it handles the database completely for you. I don't really know how to use it very well and I don't quite understand the Model-View-Controller paradigm(?) for it yet but I haven't thought about it much. I also like the fact that it uses Python. (2) I don't really like Visual Studio for developing in ASP.NET, I hate the way the web-designer works and it just feels clunky and old. I like the server-side development part though. I don't like how expensive ASP.NET and overall Visual Studio is, even if I do get it for free for now using DreamSpark (3) I haven't been able to explore much with this, I could not get Rails (or maybe Ruby) properly installed. I first installed it within RadRails and that didn't work so I uninstalled RadRails and then installed the latest version of Ruby off the official Windows Installer and then installed Ruby on Rails through gem and even after all that it still didn't work, so I installed Netbeans and attempted to use it there but it still did not work (4) I like Silverlight in some extents, I've played with this one the most, it's very similar to WPF (which I've used the most) in a lot of ways but I don't like how database connectivity works, at least in comparison to Django. I also dislike how expensive everything with Microsoft is, even if I get it for free for now with DreamSpark. I would like to hear some suggestions from experienced web-developers as to what I should use and why, or at least what some good options are for my scenario Your help would be very appreciated

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