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  • Seek Steering Behavior with Target Direction for Group of Fighters

    - by SebastianStehle
    I am implementing steering algorithms with group management for spaceships (fighters). I select a leader and assign the target positions for the other spaceships based on the target position of the leader and an offset. This works well. But when my spaceships arrive they all have a different direction. I want them to keep to look in the same direction (target - start). I also want to combine this behavior with a minimum turning radius that is based on the speed. The only idea I have is to calculate a path for each spaceship with an point before the target position, so the ships have some time left to turn into the right position. But I dont know if this is a good idea. I guess there will be a lot of rare cases where this can cause a problem. So the question is, if anybody knows how to solve this problem and has some (simple code) or pseudocode for me or at least some good explanation.

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  • Can only run firefox 8.0 in safe mode [closed]

    - by Max Popp
    This is a recent problem but I have no idea what caused it: I can only run firefox in safe mode. Any other mode, I get a completely khaki, unresponsive screen, that I have to forcibly terminate. I have uninstalled firefox, and then re-installed it via synaptic. That didn't seem to work. The problem occurs in all the four user accounts I have defined in the ubuntu. I am running an ubuntu 11.10, amd64. My firefox is version 8.0.

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  • How can I simulate objects floating on water without a physics engine?

    - by user1075940
    In my game the water movement is done in a shader using Gerstner equations. The water movement looks realistic enough for a school project but I encounter serious problem when I wanted to do sailing on waves (similar to this). I managed to do collision with land by calculating quad's vertices and normals beneath ship, however same method can not be applied to water because XZ are displaced and Y is calculated in a shader :( How to approach this problem ? Is it possible to retrieve transformed grid from shader? Unfortunately no external physics libraries can be used.

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  • Is there a better approach in migrating SIT SVN to UAT SVN?

    - by huahsin68
    In web development, given a same piece of source code, and being deploy to SIT (system integration testing) SVN/WAS and UAT (user acceptance testing) SVN/WAS. Please take note that I am using Jenkins to build everything. I have already ensured the transition from SIT SVN to UAT SVN are sync by doing manual diff on the 2 directory. Usually I will ensure the SIT WAS is working fine then only deploy to UAT WAS. But now there is a problem show up in UAT WAS and it is working fine in SIT WAS. I am suspecting there is a migration fault happened between SIT SVN to UAT SVN. In such a given scenario, is there a better approach to handle this problem?

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  • Installing windows after ubuntu is installed (need to create ntfs partition too)

    - by Brent Roose
    I prefer Ubuntu to work on, but for some applications for school, I need windows. I've done some research and have a few problems: I only have one hard drive which is formatted as ext4, not ntfs. Many people say I have to use Gparted to create an ntfs partition to install windows on, the only problem is that I need to unmount my drive to do this, which isn't possible I think because I only have one. I thought about mounting my HDD as a slave on a windows laptop but I don't manage to partition it with windows partition manager, so I think I need some kind of tool. which one? next problem I'll probably have is that I won't be able to boot ubuntu after installing windows because grub will be removed from my MBR. are there any good guides around here? I've used some kind of tool before, but it crashed my whole HDD so I had to fully format it.

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  • Creating practically solvable 15 puzzle inputs

    - by Ashwin
    I am now developing a 15 puzzle game. I know the method to detect unsolvable puzzles. But unlike 8-puzzle, solution for 15-puzzle takes quite long time for some input states and can be solved within 5 seconds some other set of input states. Now the problem is that I cannot give the user(the player), a problem for which the solution takes more than 10 seconds(if he/she chooses to see the solution). So what I want is that when I initially shuffle the puzzle, I want to only present those puzzles which can be solved within 10 seconds. There must be some way to determine the hardness of the puzzle. I tried searching the net but could not find it. Does anyone know a way of determining the hardness of a puzzle? NOTE : I am using A* algorithm to find out the solution on a computer with 3GB RAM and 2.27GHZ processor.

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  • Apple Developer Enterprise Program?

    - by Gnial0id
    I'm building an iOS application for a client (not an enterprise but non-profit association with under than 500 employess), distributed in a free version and a "paid" one. The free version will be available with iTunes/AppStore, no problem with that. But about the paid one... the distribution my client wants is different. They want to distribute it to their clients as a bonus in their subscription, and so, to control this distribution. The first answer would be "iOS Developer Enterprise Program", but it's not an enterprise and have less than 500 employees. Will the fact that my client will distribute the app' with a subscription be a problem ? I spend a lot of time to read documentation, but it is not very clear. I'm a bit lost, I admit it. Any help would grateful.

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  • Fails to boot after upgrade, stuck on winbind package

    - by Praetorian
    I started the upgrade from 11.04 to 11.10 last night. Once it got the installing packages part I left the computer unattended the rest of the night. When I checked it this morning the screen was blank and I couldn't get it to turn on. So I cycled power, and now I get the "Ubuntu 11.10" screen with the dots underneath, but then it gets to a blank screen and nothing more. I can get to the command line in recovery mode; here's a list of the things I've tried so far sudo apt-get update - the very first repository it checked sat at 0% for a long time (network cable is plugged in), so I cancelled with Ctrl+C Thought it might be a problem with display drivers, so I tried sudo apt-get install nvidia-glx - this gave me an error saying dpkg has been interrupted, manually run sudo dpkg --configure -a sudo dpkg --configure -a this installed / updated a bunch of stuff but got stuck at Starting Winbind daemon winbind Restarted and tried sudo dpkg --configure -a again but it gets stuck at same Windbind step What else can I do to fix this problem?

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  • KDE Sometimes Glitches On Wakeup

    - by Mew
    Well, a picture is work 1k words: Looks bad, huh? I am using the 331-updates latest 331.67 drivers from NVidia's website on a Dell Latitude e6400. Everything else is up-to-date. This only happens when I resume from sleep, or I switch to a VT and back. It also doesn't ALWAYS happen, which I find odd. Graphics Card: Nvidia Quadro NVS160M UPDATE AFTER TESTING: This problem only exists with KDE (specifically QT). I can go into Unity or Mint or any non QT-based GUI and it works perfectly with no resume errors. UPDATE: This only happens when I use KWin (and KDE). I have upgraded to 14.04 and the problem is not occurring as frequently. Also, sometimes this effect doesn't happen, but instead the top menu bar simply goes out of focus with the rest of the screen goes blank.

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  • Monitor blinking

    - by Shark
    Hi I have Ubuntu 10.04, my laptop is ASUS k50ij, intel duo t3000, 2gb ram, 320 HDD, intel gma 4500M video card. My problem is that a couple days ago my monitor had start blinking for a few seconds. Then it stops and begins the same behaviour let's say in next 2 hours. What am i missing here? Another funny problem is that when i give more or less brightness to monitor the pop up window shows and giving "Power information: Laptop battery is charged". When my brightness is lower the blinking increases and vice versa. thx for help

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  • Secret of SQL Trace Duration Column

    - by Dan Guzman
    Why would a trace of long-running queries not show all queries that exceeded the specified duration filter?  We have a server-side SQL Trace that includes RPC:Completed and SQL:BatchCompleted events with a filter on Duration >= 100000.  Nearly all of the queries on this busy OLTP server run in under this 100 millisecond threshold so any that appear in the trace are candidates for root cause analysis and/or performance tuning opportunities. After an application experienced query timeouts, the DBA looked at the trace data to corroborate the problem.  Surprisingly, he found no long-running queries in the trace from the application that experienced the timeouts even though the application’s error log clearly showed detail of the problem (query text, duration, start time, etc.).  The trace did show, however, that there were hundreds of other long-running queries from different applications during the problem timeframe.  We later determined those queries were blocked by a large UPDATE query against a critical table that was inadvertently run during this busy period. So why didn’t the trace include all of the long-running queries?  The reason is because the SQL Trace event duration doesn’t include the time a request was queued while awaiting a worker thread.  Remember that the server was under considerable stress at the time due to the severe blocking episode.  Most of the worker threads were in use by blocked queries and new requests were queued awaiting a worker to free up (a DMV query on the DAC connection will show this queuing: “SELECT scheduler_id, work_queue_count FROM sys.dm_os_schedulers;”).  Technically, those queued requests had not started.  As worker threads became available, queries were dequeued and completed quickly.  These weren’t included in the trace because the duration was under the 100ms duration filter.  The duration reflected the time it took to actually run the query but didn’t include the time queued waiting for a worker thread. The important point here is that duration is not end-to-end response time.  Duration of RPC:Completed and SQL:BatchCompleted events doesn’t include time before a worker thread is assigned nor does it include the time required to return the last result buffer to the client.  In other words, duration only includes time after the worker thread is assigned until the last buffer is filled.  But be aware that duration does include the time need to return intermediate result set buffers back to the client, which is a factor when large query results are returned.  Clients that are slow in consuming results sets can increase the duration value reported by the trace “completed” events.

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  • PostgreSQL data diff

    - by skanatek
    Note: this question is not about syncing database schema/structure Problem In my web application I have a PostgreSQL database server (PGS) and a (separate machine) business logic server (BLS) which regularly (every minute or two) queries 'SELECT ALL' against PGS. The problem is that the 'SELECT ALL' query can easily return 50-200 MB each time. It is obvious that it would be not so good architecture-wise to transfer so much data so frequently over the web. Possible solution What I would like to do is to run some diff tool on PGS and compare the new query with the previous query (all this should be done on PGS). Once the comparison is done I would like to get a dump from PGS and transfer it to BLS. I expect that a diff-based dump would be much, much smaller than the whole 'SELECT ALL' query. Question Is there any data diff tool for PostgreSQL that can do diffs that compare PostgreSQL data between 2 tables or 2 dumps? Note: I would prefer some open-source software tool.

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  • OpenOffice Calc doesn't show up in the alt-tab window switcher

    - by Abe
    I just upgraded to ubuntu 12.04, and it's mostly working. My biggest problem so far: OpenOffice/LibreOffice Calc doesn't show up under the task switcher. When I pres alt-tab to change windows, I can see all my windows except for any OpenOffice documents I have open. If I minimize other windows, then I can get to my Calc documents, but Alt-Tab just doesn't work. It only seems to be a problem with Calc. Writer and Impress both work fine. I do a lot of work in spreadsheets, so this is really messing up my flow. Any thoughts on how to fix it?

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  • Ubuntu took away permissions from my Data partition

    - by RobinJ
    The pangolin has struck again. The bug of the day for today is Ubuntu taking away my permissions on my Data partition (NTFS). One moment everything worked fine, the next moment I couldn't chmod anything anymore. chown throws no errors or warnings at all, but nothing has changed either. chmod keeps saying Operation not permitted. I've been messing around with /etc/fstab as suggested by other answers on AskUbuntu, but none of them seem to have the desired effect. This is my current line: UUID=25D7D681409A96B7 /media/Data ntfs defaults,umask=000,gid=46,permissions,users,auto,exec 0 0 For reference, this is the original one: UUID=25D7D681409A96B7 /media/Data ntfs defaults,umask=007,gid=46 0 0 (right after the problem started occuring) What do I need to do so I am the owner of my own hard drive again? I want to be able to just use chmod and chown (without sudo) without being told that some mysterious alien has taken over control of my Data partition. I can still read and write, but execution permissions seem to be the problem.

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  • How do I make the launcher progress bar work with my application?

    - by Kevin Gurney
    Background Research I am attempting to update the progress bar within the Unity launcher for a simple python/Gtk application created using Quickly called test; however, following the instructions in this video, I have not been able to successfully update the progress bar in the Unity launcher. In the Unity Integration video, Quickly was not used, so the way that the application was structured was slightly different, and the code used in the video does not seem to function properly without modification in a default Quickly ubuntu-application template application. Screenshots Here is a screenshot of the application icon as it is currently displayed in the Unity Launcher. Here is a screenshot of the kind of Unity launcher progress bar functionality that I would like (overlayed on mail icon: wiki.ubuntu.com). Code class TestWindow(Window): __gtype_name__ = "TestWindow" def finish_initializing(self, builder): # pylint: disable=E1002 """Set up the main window""" super(TestWindow, self).finish_initializing(builder) self.AboutDialog = AboutTestDialog self.PreferencesDialog = PreferencesTestDialog # Code for other initialization actions should be added here. self.add_launcher_integration() def add_launcher_integration(self): self.launcher = Unity.LauncherEntry.get_for_desktop_id("test.destkop") self.launcher.set_property("progress", 0.75) self.launcher.set_property("progress_visible", True) Expected Behavior I would expect the above code to show a progress bar that is 75% full overlayed on the icon for the test application in the Unity Launcher, but the application only runs and displays no progress bar when the command quickly run is executed. Problem Investigation I believe that the problem is that I am not properly getting a reference to the application's main window, however, I am not sure how to properly fix this problem. I also believe that the line: self.launcher = Unity.LauncherEntry.get_for_desktop_id("test.destkop") may be another source of complication because Quickly creates .desktop.in files rather than ordinary .desktop files, so I am not sure if that might be causing issues as well. Perhaps, another source of the issue is that I do not entirely understand the difference between .desktop and .desktop.in files. Does it possibly make sense to make a copy of the test.desktop.in file and rename it test.desktop, and place it in /usr/share/applications in order for get_for_desktop_id("test,desktop") to reference the correct .desktop file? Related Research Links Although, I am still not clear on the difference between .desktop and .desktop.in files, I have done some research on .desktop files and I have come across a couple of links: Desktop Entry Files (library.gnome.org) Desktop File Installation Directory (askubuntu.com) Unity Launcher API (wiki.ubuntu.com) Desktop Files: putting your application in the desktop menus (developer.gnome.org) Desktop Menu Specification (standards.freedesktop.org)

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  • How to set up a one-man research in the difference between BDD and Waterfall?

    - by Martijn van der Maas
    Earlier, I asked a question about how to measure the quality of a project. The outcome of that question was that the quality of the project can be divided into two parts: Internal quality (code quality, measurable by code quality metrics) External quality (Acceptance test, how well the software meets the requirements) So based on that, I want to set up some research and validate the outcome of the project. The problem is, I will conduct this research on my own, so it's not possible to run the project once in BDD style and the other one in waterfall by myself. It's also not possible to compare BDD and waterfall projects on a larger scale, due to the fact that there are not enough BDD projects that can be measured because of the age of BDD. So, my question is: did anybody face this problem? How could I execute my experiment in such a way that it is of scientific value?

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  • acer 1551 suspend/hibernate bug?

    - by user11050
    I put 64-bit Ubuntu 10.10 on my Acer 1551. It does not want to wake from suspend or hibernate. I have tried several different solutions to the apparent problem, but none have worked for me. Similar problem: Acer Aspire 1551 Will Not Wake After Suspend I tried what it suggested, no go. Also, I think it is taking my acer a while to boot-up what can I look into that may be causing it? I am new to ubuntu, and would like some help! thanks

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  • Pixel alignment algorithm

    - by user42325
    I have a set of square blocks, I want to draw them in a window. I am sure the coordinates calculation is correct. But on the screen, some squares' edge overlap with other, some are not. I remember the problem is caused by accuracy of pixels. I remember there's a specific topic related to this kind of problem in 2D image rendering. But I don't remember what exactly it is, and how to solve it. Look at this screenshot. Each block should have a fixed width margin. But in the image, the vertical white line have different width.Though, the horizontal lines looks fine.

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  • Where can I get feedback and support from other programmers in real time?

    - by cypherblue
    I used to work in an office surrounded by a large team of programmers where we all used the same languages and had different expertises. Now that I am on my own forming a startup at home, my productivity is suffering because I miss having people I can talk to for specific help, inspiration and reality checks when working on a coding problem. I don't have access to business incubators or shared (co-working) office spaces for startups so I need to chat with people virtually. Where can I go for real-time chat with other programmers and developers (currently I'm looking for people developing for the web, javascript and python) for live debugging and problem-solving of the tasks I am working on? And what other resources can I use to get fellow programmer support?

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  • Oracle's Integrated Systems Management and Support Experience

    - by Scott McNeil
    With its recent launch, Oracle Enterprise Manager 11g introduced a new approach to integrated systems management and support. What this means is taking both areas of IT management and vendor support and combining them into one integrated comprehensive and centralized platform. Traditional Ways Under the traditional method, IT operational teams would often focus on running their systems using management tools that weren’t connected to their vendor’s support systems. If you needed support with a product, administrators would often contact the vendor by phone or visit the vendor website for support and then log a service request in order to fix the issues. This method was also very time consuming, as administrators would have to collect their software configurations, operating systems and hardware settings, then manually enter them into an online form or recite them to a support analyst on the phone. For the vendor, they had to analyze all the configuration data to recreate the problem in order to solve it. This approach was very manual, uncoordinated and error-prone where duplication between the customer and vendor frequently occurred. A Better Support Experience By removing the boundaries between support, IT management tools and the customer’s IT infrastructure, Oracle paved the way for a better support experience. This was achieved through integration between Oracle Enterprise Manager 11g and My Oracle Support. Administrators can not only manage their IT infrastructure and applications through Oracle Enterprise Manager’s centralized console but can also receive proactive alerts and patch recommendations right within the console they use day-in-day-out. Having one single source of information saves time and potentially prevents unforeseen problems down the road. All for One, and One for All The first step for you is to allow Oracle Enterprise Manager to upload configuration data into Oracle’s secure configuration repository, where it can be analyzed for potential issues or conflicts for all customers. A fix to a problem encountered by one customer may actually be relevant to many more. The integration between My Oracle Support and Oracle Enterprise Manager allows all customers who may be impacted by the problem to receive a notification about the fix. Once the alert appears in Oracle Enterprise Manager’s console, the administrator can take his/her time to do further investigations using automated workflows provided in Oracle Enterprise Manager to analyze potential conflicts. Finally, administrators can schedule a time to test and automatically apply the fix to all the systems that need it. In the end, this helps customers maintain their service levels without compromise and avoid experiencing unplanned downtime that may result from potential issues or conflicts. This new paradigm of integrated systems management and support helps customers keep their systems secure, compliant, and up-to-date, while eliminating the traditional silos between IT management and vendor support. Oracle’s next generation platform also works hand-in-hand to provide higher quality of service to business users while at the same time making life for administrators less complicated. For more information on Oracle’s integrated systems management and support experience, be sure to visit our Oracle Enterprise Manager 11g Resource Center for the latest customer videos, webcast, and white papers.

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  • How to generate xorg.conf? (X -configure segfaults)

    - by Nicolas Raoul
    My video card is working fine, I have no screen problem. I am trying to generate an xorg.conf so I did: [ Logout ] sudo service gdm stop [ Move away xorg.conf.back and xorg.conf.fglrx-0 that were in /etc/X11 ] sudo dpkg-reconfigure xserver-xorg sudo X -configure But this last command segfaults: X.Org X Server 1.7.6 Release Date: 2010-03-17 X Protocol Version 11, Revision 0 Build Operating System: Linux 2.6.24-27-server i686 Ubuntu Current Operating System: Linux nico 2.6.32-25-generic #44-Ubuntu SMP Fri Sep 17 20:26:08 UTC 2010 i686 Kernel command line: BOOT_IMAGE=/boot/vmlinuz-2.6.32-25-generic root=UUID=7447ab16-3406-442d-81e5-bb6a2d795205 ro quiet splash Build Date: 21 July 2010 12:47:34PM xorg-server 2:1.7.6-2ubuntu7.3 (For technical support please see http://www.ubuntu.com/support) Current version of pixman: 0.16.4 Before reporting problems, check http://wiki.x.org to make sure that you have the latest version. Markers: (--) probed, (**) from config file, (==) default setting, (++) from command line, (!!) notice, (II) informational, (WW) warning, (EE) error, (NI) not implemented, (??) unknown. (==) Log file: "/var/log/Xorg.0.log", Time: Fri Oct 15 16:06:11 2010 List of video drivers: i740 ark geode siliconmotion mach64 s3 r128 apm intel neomagic vesa trident chips s3virge fglrx sis savage rendition i128 tseng ztv mga openchrome radeon ati nv v4l vmware cirrus tdfx nouveau sisusb voodoo fbdev (EE) Can't load FireGL DRM library (libfglrxdrm.so). Backtrace: 0: X (xorg_backtrace+0x3b) [0x80e938b] 1: X (0x8048000+0x61c8d) [0x80a9c8d] 2: (vdso) (__kernel_rt_sigreturn+0x0) [0x34d410] 3: X (xf86CallDriverProbe+0x182) [0x80b82d2] 4: X (DoConfigure+0x1c8) [0x816b898] 5: X (InitOutput+0x1da) [0x80b98aa] 6: X (0x8048000+0x1ebbb) [0x8066bbb] 7: /lib/tls/i686/cmov/libc.so.6 (__libc_start_main+0xe6) [0x467bd6] 8: X (0x8048000+0x1e961) [0x8066961] Segmentation fault at address (nil) Caught signal 11 (Segmentation fault). Server aborting Please consult the The X.Org Foundation support at http://wiki.x.org for help. Please also check the log file at "/var/log/Xorg.0.log" for additional information. ddxSigGiveUp: Closing log Note the line Can't load FireGL DRM library (libfglrxdrm.so) Note: I do have file /usr/lib/fglrx/xorg/modules/linux/libfglrxdrm.so It is strange that it segfaults whereas I can use Gnome with no problem but well... Might be related: I tried to install the driver from ATI's website recently, and from then glxgears crashes at start. How can I generate xorg.conf in those conditions? It might or might not involve solving the segfault problem.

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  • Ubuntu hangs on booting up after a update

    - by alFReD NSH
    I've made a clean install yesterday, for the first time restarted, everything went good and then after I updated packages and copied my old home directory to replace the new one, when I restarted it hung when it was booting. I tried reinstalling again and doing the same thing, but again same thing happened. Here's what I see, before when the Ubuntu logo with the five dots is shown: Then after that, 3 or 4 of the dots will load and hangs there. If I press arrow up before that, this will be shown I started my laptop again today(the pictures are for the day before) and after that, boot up with live CD and got the logs. dmesg: http://pastebin.com/aVxV7BQF syslog: http://pastebin.com/4E2BrRUK And some info: alfred@alFitop:~$ uname -a Linux alFitop 3.2.0-24-generic #39-Ubuntu SMP Mon May 21 16:52:17 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux lshw: http://pastebin.com/AZbKJmsT sources.list : http://pastebin.com/2HazmuyV My problem is a bit similar to here: http://ubuntuforums.org/showthread.php?t=1918271 Though I didn't change my x.org config. Only changed home directory and updated packages. I've tried memtest and fschk, both passed. In the recovery mode boot option, I've also realized that same things happen in failsafe graphical mode. But when I go into the network mode, I can boot up my system, but of course same the graphics are just basic. Adding blacklist intel_ips to /etc/modprobe.d/blacklist.conf solves the first message, but still I get the broken pipe and CPU stack traces. The current kernel version is 3.2.0-25, I've tried booting up in the 3.2.0-23(the one the installer came with, but same results.) Also uninstalled apparmor, didn't help. I've installed Ubuntu again, this time without copying the home directory, also same result. --- UPDATE --- This problem was solved before with removing backports, but its back again! I've updated my laptop last night and the problem came back. It's definitely one of these packages. My /var/log/apt/term.log and /var/log/apt/history.log. I'm almost having the same situation. --- UPDATE --- I realized this also have happened on times that I have updated(haven't restarted after it) and my computer power has been cut off and its shutdown due to lack of power. And I realized if I just do as I answered but not in somewhere without GUI(networking mode has the GUI) it wouldn't work.

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  • Cannot assign keys to Wacom scroll wheel anymore

    - by UncleZeiv
    Hi all, my Wacom Graphire 4 used to work perfectly well until, I think, Ubuntu 10.4. At that point something changed in the configuration and I couldn't assign a key to the scroll wheel anymore (note: the pad's scroll wheel, not the mouse's), i.e this command: xsetwacom set "Wacom Graphire4 6x8 pad" AbsWDn "key +" returns silently without error but nothing happens. Same goes for AbsWUp, RelWDn, RelWUp. Apparently though the problem is even deeper as pressing the wheel in a xev window doesn't seem to have any effect. Moreover I am thoroughly confused on how the various pieces (kernel driver, xorg driver, evdev, HAL, xinput?) are supposed to work together and if the wacom module that ships with Ubuntu is the one from linuxwacom or not. Any ideas? I don't want to become an X.org hacker just to understand what's going on... it used to work! NOTE: I have already read question 3940, but that's not the same problem.

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  • Calling functions from different classes

    - by A Ron Hubbard Clevenger
    I'm writing a program and I'm supposed to check and see if a certain object is in the list before I call it. I set up the contains() method which is supposed to use the equals() method of the Comparable interface I implemented on my Golfer class but it doesn't seem to call it (I put print statements in to check). I can't seem to figure out whats wrong with the code, the ArrayUnsortedList class I'm using to go through the list even uses the correct toString() method I defined in my Golfer class but for some reason it won't use the equals() method I implemented. //From "GolfApp.java" public class GolfApp{ ListInterface <Golfer>golfers = new ArraySortedList<Golfer> (20); Golfer golfer; //..*snip*.. if(this.golfers.contains(new Golfer(name,score))) System.out.println("The list already contains this golfer"); else{ this.golfers.add(this.golfer = new Golfer(name,score)); System.out.println("This golfer is already on the list"); } //From "ArrayUnsortedList.java" protected void find(T target){ location = 0; found = false; while (location < numElements){ if (list[location].equals(target)) //Where I think the problem is { found = true; return; } else location++; } } public boolean contains(T element){ find(element); return found; } //From "Golfer.java" public class Golfer implements Comparable<Golfer>{ //..irrelavant code sniped..// public boolean equals(Golfer golfer) { String thisString = score + ":" + name; String otherString = golfer.getScore() + ":" + golfer.getName() ; System.out.println("Golfer.equals() has bee called"); return thisString.equalsIgnoreCase(otherString); } public String toString() { return (score + ":" + name); } My main problem seems to be getting the find function of the ArrayUnsortedList to call my equals function in the find() part of the List but I'm not exactly sure why, like I said when I have it printed out it works with the toString() method I implemented perfectly. I'm almost positive the problem has to do with the find() function in the ArraySortedList not calling my equals() method. I tried using some other functions that relied on the find() method and got the same results.

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  • How do we keep dependent data structures up to date?

    - by Geo
    Suppose you have a parse tree, an abstract syntax tree, and a control flow graph, each one logically derived from the one before. In principle it is easy to construct each graph given the parse tree, but how can we manage the complexity of updating the graphs when the parse tree is modified? We know exactly how the tree has been modified, but how can the change be propagated to the other trees in a way that doesn't become difficult to manage? Naturally the dependent graph can be updated by simply reconstructing it from scratch every time the first graph changes, but then there would be no way of knowing the details of the changes in the dependent graph. I currently have four ways to attempt to solve this problem, but each one has difficulties. Nodes of the dependent tree each observe the relevant nodes of the original tree, updating themselves and the observer lists of original tree nodes as necessary. The conceptual complexity of this can become daunting. Each node of the original tree has a list of the dependent tree nodes that specifically depend upon it, and when the node changes it sets a flag on the dependent nodes to mark them as dirty, including the parents of the dependent nodes all the way down to the root. After each change we run an algorithm that is much like the algorithm for constructing the dependent graph from scratch, but it skips over any clean node and reconstructs each dirty node, keeping track of whether the reconstructed node is actually different from the dirty node. This can also get tricky. We can represent the logical connection between the original graph and the dependent graph as a data structure, like a list of constraints, perhaps designed using a declarative language. When the original graph changes we need only scan the list to discover which constraints are violated and how the dependent tree needs to change to correct the violation, all encoded as data. We can reconstruct the dependent graph from scratch as though there were no existing dependent graph, and then compare the existing graph and the new graph to discover how it has changed. I'm sure this is the easiest way because I know there are algorithms available for detecting differences, but they are all quite computationally expensive and in principle it seems unnecessary so I'm deliberately avoiding this option. What is the right way to deal with these sorts of problems? Surely there must be a design pattern that makes this whole thing almost easy. It would be nice to have a good solution for every problem of this general description. Does this class of problem have a name?

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