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• Fresh install of Ubuntu 12.10 won't boot on Asus X101CH Eee PC

  - by Najdmie

  I did a fresh install of Ubuntu 12.10 in my Asus X101CH Eee PC, using a live usb which I made using startup disk creator, replacing Ubuntu 12.04. The installation ran smoothly, but when I boot, it goes to a purple screen for a second, then a lot of text like the following shows up in sequence: Starting crash report submission daemon [OK] Starting CPU interrupts balancing daemon [OK] Stopping save kernel messages [OK] _ And the cursor just keeps blinking for hours. I can't log in. Pressing Alt + F2 did not bring me to console mode. I thought it might be a partition problem so I formatted the whole disk, by creating a new partition table using gparted in Ubuntu 12.04 live USB. I noticed that I can't try Ubuntu using 12.10 live USB either; it just went to a blank screen when I hit the 'try ubuntu' button. But the same problem arose. I even changed the pen drive for the live USB a couple of times. I happened to know that the Intel Atom N2600 Cedar Trail CPU in my computer is not well supported in Linux, I managed to install its drivers in Ubuntu 12.04, although the computer went blank during the installation.

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• How to visually "connect" skybox edges with terrain model

  - by David

  I'm working on a simple airplane game where I use skybox cube rendered using disabled depth test. Very close to the bottom side of the skybox is my terrain model. What bothers me is that the terrain is not connected to the skybox bottom. This is not visible while the plane flies low, but as it gets some altitude, the terrain looks smaller because of the perspective. Since the skybox center is always same as the camera position, the skybox moves with the plane, but the terrain goes into the distance. Ok, I think you understand the problem. My question is how to fix it. It's an airplane game so limiting max altitude is not possible. I thought about some way to stretch terrain to always cover whole bottom side of the skybox cube, but that doesn't feel right and I don't even know how would I calculate new terrain dimensions every frame. Here are some screenshot of games where you can clearly see the problem: (oops, I cannot post images yet) darker brown is the skybox bottom here: http://i.stack.imgur.com/iMsAf.png untextured brown is the skybox bottom here: http://i.stack.imgur.com/9oZr7.png

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• Where can I find design exercises to work on?

  - by Oak

  I feel it's important to continue practicing my problem-solving skills. Writing my own mini-projects is one way, but another is to try and solve problems posted online. It's easy to find interesting programming quizzes online that require applying clever algorithms to solve - Project Euler is one well-known example. However, in a lot of real-life projects the design of the software - especially in the initial phases - has a large impact and at later stages it cannot be tweaked as easily as plain algorithms. In order to improve these skills, I'm looking for any collection of design problems. When I say "design", I mean the abstract design of a software solution - for example what modules will there be and what are the dependencies between them, how data will flow in the program, what sort of data needs to be saved in the database, etc. Design problems are those problems that are critical to solve in the early stages of any project, but their solution is a whiteboard diagram without a single line of code. Of course these sort of problems do not have a single correct solution, but I'll be especially happy with any place that also displays pros and cons of the typical solutions that might be used to approach the problem.

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• ORA-600 Troubleshooting

  - by [email protected]

  Have you observed an ORA-0600 or ORA-07445 reported in your alert log? The ORA-600 error is the generic internal error number for Oracle program exceptions. It indicates that a process has encountered a low-level, unexpected condition. The ORA-600 error statement includes a list of arguments in square brackets: ORA 600 "internal error code, arguments: [%s], [%s],[%s], [%s], [%s]" The first argument is the internal message number or character string. This argument and the database version number are critical in identifying the root cause and the potential impact to your system.  The remaining arguments in the ORA-600 error text are used to supply further information (e.g. values of internal variables etc).   Looking for the best way to diagnose? There is an ORA-600 Troubleshooter Tool available in My Oracle Support.  This tool will lead you to applicable content in My Oracle Support on the problem and can be used to investigate the problem with argument data from the error message or you can pull out the first 10 or 15 stack pointers from the associated trace file to match up against known bugs. Note 153788.1 ORA-600/ORA-7445 TroubleshooterNote 1082674.1 A Video To Demonstrate The Usage Of The ORA-600/ORA-7445 Lookup Tool [Video] Also, take a quick look at the Master Note for Diagnosing ORA-600 ( MasterNoteORA600.docx) for some tips on diagnosing.

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• What methods should save/load a game state

  - by vedi

  There are a lot of articles about how to save a state of a game and they are pretty good. But I have one conceptual misunderstanding where should I save the state? My game has number of screens and pair of them are MainMenuScreen and MainSceneScreen these are inherited from Screen class. MainMenuScreen is shown at start of the game the MainSceneScreen little later. What is the problem? I navigated to MainSceneScreen, forced Android to stop the application (I change a language settings on the device to achieve it, please let me know if I'm wrong). After that I select the application again and I can see MainMenuScreen is shown. But I want MainSceneScreen to be shown. I suppose I should override resume method. But what class I should override? I have class PsGame that extends Game class of libgdx. I put breakpoints to its resume method and it turned out that method was not called. I investigated the problem and I've found little strange code in onResume method of AndroidApplication class of libgdx: if (!firstResume) graphics.resume(); else firstResume = false; My debugger said firstResume was true and didn't go to *graphics.resume()*line. Sorry for a lot of words but could you answer following question: What did I do wrong? What methods should I override? Thank you in advance.

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• Seeking solution for printing-reporting .NET

  - by Parhs

  I am developing an application that prints in separate threads in extreme cases about 20-25 pages per minute to various thermal printers. Currently templates for these are XAML xps documents. All printers have graphics drivers that support EMF/GDI printing. So GDI-EMF is done by operating system resulting in slower performance. Sending raw text for printing is another good solution but doesnt work always , because some clients have old chinese thermal printer that nobody support thus impossible to change codepage / emulation. So it doesnt work always. Also most computers running my software are low end ATOM CPU. So I am thinking to return to GDI, EMF printing and have both Text-Only reports and EMF reports. Another reason i want EMF is because here receipts are signed by Electronic Fiscal Memory device.Most of these dont do good job extracting text from XPS as they dont follow the standard but how windows convert GDI to XPS.Even with text-only mode some of them dont support all character encodings and are impossible to send paper cut command after the sign. I know that using a reporting engine would solve rendering problem but I dont want to buy one. All I want is to be able to show tabular data and insert an image and replaced text.I know there is StringTemplate that could do the generation of template but the problem is i should parse somehow the template and render it using GDI commands. Is there any other solution/approach for this ? Or is there anything ready ?

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• How to mange big amount users at server side?

  - by Rami

  I built a social android application in which users can see other users around them by gps location. at the beginning thing went well as i had low number of users, But now that I have increasing number of users (about 1500 +100 every day) I revealed a major problem in my design. In my Google App Engine servlet I have static HashMap that holding all the users profiles objects, currenty 1500 and this number will increase as more users register. Why I'm doing it Every user that requesting for the users around him compares his gps with other users and check if they are in his 10km radius, this happens every 5 min on average. That is why I can't get the users from db every time because GAE read/write operation quota will tare me apart. The problem with this desgin is As the number of users increased the Hashmap turns to null every 4-6 hours, I thing that this time is getting shorten but I'm not sure. I'm fixing this by reloading the users from the db every time I detect that it became null, But this causes DOS to my users for 30 sec, So I'm looking for better solution. I'm guessing that it happens because the size of the hashmap, Am I right? I have been advised to use spatial database, but that mean that I can't work with GAE any more and that mean that I need to build my big server all over again and lose my existing DB. Is there something I can do with the existing tools? Thanks.

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• Development teams do not scale

  - by Matt Watson

  Recently I have been thinking about how development teams don't scale very well. The bigger a team and the product get, the more time the team spends fixing software bugs. This means they spend more time doing troubleshooting and debugging as the grow. The problem is that since developers don't typically have access to production servers, there is a bottleneck in the process when doing production troubleshooting.For a team that has 10 developers, I would guess than 0-2 of them have access to production servers. If that team grows to 20 people, it is probably the same 0-2 people that have production access still. This means that those 2 key people are a bottleneck and the team does not scale correctly as you add more resources. All those new developers want is to help track down and fix software bugs, but they don't have the visibility to do it. So they end up being less productive and frustrated because they really want to fix the problems. The people who do have production access end up spending too much of their time doing troubleshooting instead of working on new projects.The solution is to remove the bottlenecks and get those people working on more important tasks. Stackify can solve this problem by giving all the developers read only access to production servers. This allows them to access the information they need to do troubleshooting on their own.

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• Ubuntu 11.10 and Mobility radeon HD 4570, 512MB can't find working drivers

  - by Slavak

  i'm pretty new to Linux and my new problem is ATI drivers. When i installed Ubuntu then i had black screen issue with the blinking in left upper corner, fixed it with F6 and set the "nolapic" mode, can boot only with "nolapic". Now the problem is the drivers. The suggested drivers, from the "Additional drivers" are not working. Always freeze at the login screen, the divers are: ATI/AMD proprietary FGLRX graphics driver Tried this method: http://drivers.downloadatoz.com/tutorial/28786,how-to-fix-amd-catalyst-11-10-not-working-on-ubuntu-11-10-issues.html? but this method break it down really hard, not ever that helped anymore: sudo /usr/share/ati/fglrx-uninstall.sh # (if it exists); sudo apt-get remove --purge fglrx*; sudo apt-get remove --purge xserver-xorg-video-ati xserver-xorg-video-radeon ; sudo apt-get install xserver-xorg-video-ati; sudo apt-get install --reinstall libgl1-mesa-glx libgl1-mesa-dri xserver-xorg-core; sudo dpkg-reconfigure xserver-xorg Now i'm here with a fresh install and i cant find anything that works, can someone help me please! I like Ubuntu, but i need to get rid of the lagg, or its Windows 7 only for me then :( Thanks for reading!

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• How to run an Application as another user?

  - by takpar

  I use krusader for file management stuff. the problem is that apache's DocumentRoot should be under chown www-data:www-data /path/to/www. so using krusader (which is run under my account) I've not write access to /path/to/www while I really need. I don't know how other developers can continue doing things with such a restriction! I wondered if I could run krusader as www-data then I will be able to easily play with files. but using su - www-data asked me for www-data's password!! So, how can I run an application (like krusader) as another user (like www-data) in Gnome? or is there any other solution for my case? (tough I'm really curious to know the answer!) keep in mind that I know I can run it as root! but this will cause some permission problems when using cp and mkdir, you know. PS: sudo and gksudo did not help: $ gksudo -u -www-data krusader No protocol specified krusader: cannot connect to X server :0.0 Final Note: according the best answer, i did chmod u+w /path/to/www and my problem solved. but i still has not been succeeded in opening krusader as another user!

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• How do I adjust the origin of rotation for a group of sprites?

  - by Jon

  I am currently grouping sprites together, then applying a rotation transformation on draw: private void UpdateMatrix(ref Vector2 origin, float radians) { Vector3 matrixorigin = new Vector3(origin, 0); _rotationMatrix = Matrix.CreateTranslation(-matrixorigin) * Matrix.CreateRotationZ(radians) * Matrix.CreateTranslation(matrixorigin); } Where the origin is the Centermost point of my group of sprites. I apply this transformation to each sprite in the group. My problem is that when I adjust the point of origin, my entire sprite group will re-position itself on screen. How could I differentiate the point of rotation used in the transformation, from the position of the sprite group? Is there a better way of creating this transformation matrix? EDIT Here is the relevant part of the Draw() function: Matrix allTransforms = _rotationMatrix * camera.GetTransformation(); spriteBatch.Begin(SpriteSortMode.BackToFront, null, null, null, null, null, allTransforms); for (int i = 0; i < _map.AllParts.Count; i++) { for (int j = 0; j < _map.AllParts[0].Count; j++) { spriteBatch.Draw(_map.AllParts[i][j].Texture, _map.AllParts[i][j].Position, null, Color.White, 0, _map.AllParts[i][j].Origin, 1.0f, SpriteEffects.None, 0f); } } This all works fine, again, the problem is that when a rotation is set and the point of origin is changed, the sprite group's position is offset on screen. I am trying to figure out a way to adjust the point of origin without causing a shift in position. EDIT 2 At this point, I'm looking for workarounds as this is not working. Does anyone know of a better way to rotate a group of sprites in XNA? I need a method that will allow me to modify the point of rotation (origin) without affecting the position of the sprite group on screen.

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• Disabling shutdown command for all users, even root - consequences?

  - by Rich

  I would like to disable the shutdown command for all users, even root, on an Ubuntu Server installation. The reason I want to do this is to ensure that I don't get into the habit of shutting down the machine in this way, as I SSH into a lot of production machines at the same time as this one, and I don't want to accidentally shutdown one of the other machines by typing the command into the wrong window. The server I want do disable shutdown on only runs inside VirtualBox on my Windows desktop, and I only use it for local testing so it is not a problem if I can't shut it down from the command line. I have already mitigated the problem a bit by ensuring I have a different password on the VirtualBox image, but obviously if I am within the sudo 'window' on one of the production machines, I could still accidentally shut it down. My questions are: How do I disable the shutdown command? If I do disable the shutdown command, are there any consequences that I should be made aware of? Most specifically, will it disable support for ACPI shutdown that is the equivalent of pressing the power button on a physical machine? Could it affect other generic applications? For information, I just use this VirtualBox image for trying out shell scripts, running Tomcat and Java, and that kind of thing.

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• Huawei e303c data-card not working for Ubuntu 11.04?

  - by Umashankar

  Cheers to you. I got a problem in making a Mobile-BroadBand connection in Ubuntu 11.04, using 'Huawei e303c' usb data-card. I'm using Tata Docomo 3G sim-card (India, circle: Maharastra). My observations: 1.) I installed the device's driver 'Mobile-Partner For Linux'(which came up with the device). But it is not detecting my device. 2.) In Network Manager, Adding a Mobile-BroadBand connection is not able to detect the device (with or without the device's driver installed). 3.)I tried softwares like usb_modeswitch, gnomeppp, wvdial, sakis3G and followed their guidelines. These too didn't work. 4.) Without the driver, the system is able to identify the device (Mobile-Partner icon comes-up, that leads to driver setup files). But after installing the driver, nothing comes-up there. 5.) In all the above cases, when 'lsusb' cmd is fired, the prompt shows the connected data card (as 'DEVICE_ID:VENDOR_ID Huawei Technologies Ltd.,'). This is my problem. Give a solution to get my device connected. -Umash

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• JUnit Testing in Multithread Application

  - by e2bady

  This is a problem me and my team faces in almost all of the projects. Testing certain parts of the application with JUnit is not easy and you need to start early and to stick to it, but that's not the question I'm asking. The actual problem is that with n-Threads, locking, possible exceptions within the threads and shared objects the task of testing is not as simple as testing the class, but testing them under endless possible situations within threading. To be more precise, let me tell you about the design of one of our applications: When a user makes a request several threads are started that each analyse a part of the data to complete the analysis, these threads run a certain time depending on the size of the chunk of data (which are endless and of uncertain quality) to analyse, or they may fail if the data was insufficient/lacking quality. After each completed its analysis they call upon a handler which decides after each thread terminates if the collected analysis-data is sufficient to deliver an answer to the request. All of these analysers share certain parts of the applications (some parts because the instances are very big and only a certain number can be loaded into memory and those instances are reusable, some parts because they have a standing connection, where connecting takes time, ex.gr. sql connections) so locking is very common (done with reentrant-locks). While the applications runs very efficient and fast, it's not very easy to test it under real-world conditions. What we do right now is test each class and it's predefined conditions, but there are no automated tests for interlocking and synchronization, which in my opionion is not very good for quality insurances. Given this example how would you handle testing the threading, interlocking and synchronization?

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• NVIDIA Graphics - resolution problems with new 12.04 LTS installation

  - by Daveisuser56810

  I've been trying to install Ubuntu 12.04 LTS on my desktop most of the day. The desktop uses a NVIDIA GEFORCE 9800 (GT I think) graphics card. I am unable to set the correct resolution (1680 x 1050) for the display. The first problem I had was that of the "Black Screen" during install. I overcame this by utilising the "nomodeset" switch on the install options (once I'd found how to do that). The second problem of course was the "Black screen" following the first reboot. Once again this was overcome by using "nomodeset", this time by "editing" the GRUB. This gave me a resolution of 1280x768 which, the Displays GUI allowed me to change to 1280x720 (appears to fit on screen). I then tried to install the NVIDIA drivers. 1) using additional drivers 2) manually by downloading driver and installing in root As soon as NVIDIA drivers are installed - resolution become restricted to 640x480 (max). At this resolution Ubuntu GUI is not usable as most screens are larger than the display. Removing the NVIDIA driver and removing the XORG.CONF file does not lift this restriction. I have tried most things that I have found and that were vaguely intelligible, but nothing appears to get me closer to a resolution of 1680x1050. UPDATE: reinstalled Ubuntu 12-04 and used the "NoModeSet" in the Grub to restore the resolution to 1280x720, which is at least usable. Will live with this for now.

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• Cannot mount USB drive -- FSTAB error

  - by user107646

  Recently, one of my desktops seems to have developed a problem with the fstab and mounting USB drives. The specific error I receive is... Unable to mount TRAVELDRIVE Error mounting: mount exited with exit code 1: helper failed with: Unprivileged user can not mount NTFS block devices using the external FUSE library. Either mount the volume as root, or rebuild NTFS-3G with integrated FUSE support and make it setuid root. Please see more information at http://tuxera.com/community/ntfs-3g-faq/#unprivileged The contents of my fstab are... /etc/fstab: static file system information. # # <file system> <mount point> <type> <options> <dump> <pass> proc /proc proc nodev,noexec,nosuid 0 0 #Entry for /dev/sdc1 : UUID=7e3431cd-522f-4e35-b286-4300fa702d4a / ext4 errors=remount-ro 0 1 #Entry for /dev/sda1 : UUID=60684D08684CDE82 /media/Archive ntfs-3g defaults,locale=en_US.UTF-8 0 0 #Entry for /dev/sdc5 : UUID=cd166221-4b1d-40f7-b9de-785208990587 none swap sw 0 0 /dev/sdd1 /media/sdd1 ntfs nls=iso8859-1,ro,users,umask=000,user 0 0 /dev/sdd5 /media/PS3 (fat32) vfat users,user 0 0 /dev/sdd5 /media/sdd5 vfat uid=m3talhead,users,user 0 0 I'm guessing its a problem with the duplicate /dev/sdd5 entries (?), but being the *nix noob I am, I'm not certain. What am I missing? Any assist is greatly appreciated!

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• Host grub error after installing Virtualbox - Non Recoverable

  - by BiggJJ

  I have been unable to fine a resolution to my problem and I have been suffering from it for a while. I can install Virtualbox and can reboot the machine successfully straight after. Once the system is back up I can run Virtualbox ans start working towards creating a new machine. So, say I am installing an XP machine. 1 time out of 10 it will work successfully first time. If it doesn't work (i.e BSOD), I delete the machine and start again. But when the time comes to finish up and switch off my computer, but it doesn't happen gracefully. As soon as I click shutdown, The machine dies. When the machine is switched back on I get: Error: no such device grub resuce I boot up my Grub Fix Live CD, but the grub reinstaller get stuck on searching for partitions, gparted just get stuck looking for devices and even fdisk -l drops a line and displays nothing and is the same. Stuck. The only way I know how to sort it is by re-installing Ubuntu. Has anyone had this problem, or know how to fix it?

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• Documenting mathematical logic in code

  - by Kiril Raychev

  Sometimes, although not often, I have to include math logic in my code. The concepts used are mostly very simple, but the resulting code is not - a lot of variables with unclear purpose, and some operations with not so obvious intent. I don't mean that the code is unreadable or unmaintainable, just that it's waaaay harder to understand than the actual math problem. I try to comment the parts which are hardest to understand, but there is the same problem as in just coding them - text does not have the expressive power of math. I am looking for a more efficient and easy to understand way of explaining the logic behind some of the complex code, preferably in the code itself. I have considered TeX - writing the documentation and generating it separately from the code. But then I'd have to learn TeX, and the documentation will not be in the code itself. Another thing I thought of is taking a picture of the mathematical notations, equations and diagrams written on paper/whiteboard, and including it in javadoc. Is there a simpler and clearer way? P.S. Giving descriptive names(timeOfFirstEvent instead of t1) to the variables actually makes the code more verbose and even harder too read.

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• MAAS/JuJu Clarifications

  - by ectoskeleton

  I really love the concept of MAAS underlying an OpenStack implementation, but there are a few questions about MAAS that I am not entirely clear on. Should all hosts be set to network boot at all times or after they have been registered and allocated as a service, should they boot to disk? After juju bootstrap is executed, I turn on the machine that has been allocated (note WoL isn't working, I suspect it's being blocked on the network), the machine boot's up and then juju status executes correct, agent running and all that good stuff. If I 'reboot' the machine (testing power failure/problem whatever), juju status comes back but the agent-state is no longer in running state, and so far I have to destroy the environment and restart. In all cases I have never been able to deploy any services to any of the other nodes. I deploy the service with juju, note which node it was assigned, and then start the system. The system just boots up into a basic node. If I SSH to it I have to enter password, so it's not setting up the ssh key or anything. This is on Ubuntu 12.04.1 LTS systems and HP GL360G7 hosts. The MAAS management server is running as a VM but all on the same network. At this point I am not sure if I am doing something wrong or if there is a problem somewhere else. Is the idea that anytime a host is rebooted it should be rebuilt from the ground up, or is something else going on behind the scene to tell it to boot the local image. If the latter, why doesn't the agent start on a system that has been successfully setup before (juju bootstrapped system)?

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• Microsoft IntelliMouse episodic pauses

  - by Rob Hills

  I have a Microsoft IntelliMouse connected via USB to a computer (directly, NOT via hub) currently running Ubuntu 11.10, but this problem also existed before we upgraded from 10.10. Every now and then (apparently randomly) the computer "pauses" for anything up to a few seconds. This usually occurs after a mouse movement and during the pause, the computer is completely unresponsive to mouse or keyboard. lsusb shows: Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 005 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 001 Device 002: ID 0409:0058 NEC Corp. HighSpeed Hub Bus 001 Device 004: ID 05e3:0605 Genesys Logic, Inc. USB 2.0 Hub [ednet] Bus 003 Device 013: ID 045e:001e Microsoft Corp. IntelliMouse Explorer Bus 001 Device 005: ID 04a9:1097 Canon, Inc. PIXMA iP5000 Bus 001 Device 006: ID 0a5c:200a Broadcom Corp. Bluetooth dongle Bus 001 Device 007: ID 0911:1c57 Philips Speech Processing Bus 001 Device 008: ID 04a9:2219 Canon, Inc. CanoScan 9950F so the mouse appears to be correctly identified. Syslog episodically shows the following sequence: Jan 15 11:48:32 kayes-computer kernel: [10588.512036] usb 3-1: USB disconnect, device number 10 Jan 15 11:48:33 kayes-computer kernel: [10589.248026] usb 3-1: new low speed USB device number 11 using uhci_hcd Jan 15 11:48:33 kayes-computer mtp-probe: checking bus 3, device 11: "/sys/devices/pci0000:00/0000:00:1d.1/usb3/3-1" Jan 15 11:48:33 kayes-computer kernel: [10589.448596] input: Microsoft Microsoft IntelliMouse® Explorer as /devices/pci0000:00/0000:00:1d.1/usb3/3-1/3-1:1.0/input/input11 Jan 15 11:48:33 kayes-computer kernel: [10589.448706] generic-usb 0003:045E:001E.000B: input,hidraw0: USB HID v1.00 Mouse [Microsoft Microsoft IntelliMouse® Explorer] on usb-0000:00:1d.1-1/input0 Jan 15 11:48:33 kayes-computer mtp-probe: bus: 3, device: 11 was not an MTP device though I can't confirm if these are directly associated with the "pauses". Any thoughts on what might be causing this or what else I can do to diagnose the problem?

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• Perfomance of 8 bit operations on 64 bit architechture

  - by wobbily_col

  I am usually a Python / Database programmer, and I am considering using C for a problem. I have a set of sequences, 8 characters long with 4 possible characters. My problem involves combining sets of these sequences and filtering which sets match a criteria. The combinations of 5 run into billions of rows and takes around an hour to run. So I can represent each sequence as 2 bytes. If I am working on a 64 bit architechture will I gain any advantage by keeping these data structures as 2 bytes when I generate the combinations, or will I be as well storing them as 8 bytes / double ? (64 bit = 8 x 8) If I am on a 64 bit architecture, all registers will be 64 bit, so in terms of operations that shouldn´t be any faster (please correct me if I am wrong). Will I gain anything from the smaller storage requirements - can I fit more combinations in memory, or will they all take up 64 bits anyway? And finally, am I likley to gain anything coding in C. I have a first version, which stores the sequence as a small int in a MySQL database. It then self joins the tabe to itself a number of times in order to generate all the possible combinations. The performance is acceptable, depending on how many combinations are generated. I assume the database must involve some overhead.

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• http to https upgrade -- SEO troubles

  - by SLIM

  I upgraded my site so that all pages have gone from using http to https. I didn't consider that Google treats https pages differently than http. I re-created my sitemap to so that all links now reflect the new https and let it be for a few days. (Whoops!) Google is now re-indexing all https pages. I have about 19k pages on the site, and Google has already indexed about 8k of the new https. The problem is that Google sees all of these as brand new pages when many of them have a long http history. Of course most of you will recognize the problem, I didn't set up a 301 from the old http to the new https. Is it too late to do this? Should I switch my sitemap back to http and then 301 to the new https? Or should I leave the sitemap as is, and setup 301 redirects anyway.. I'm not even sure if Google is trying to reach the http site anymore. Currently the site is doing 303 redirects (from http to https), although I haven't figured out why yet. Thanks for any suggestions you can offer.

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• Making LISPs manageable

  - by Andrea

  I am trying to learn Clojure, which seems a good candidate for a successful LISP. I have no problem with the concepts, but now I would like to start actually doing something. Here it comes my problem. As I mainly do web stuff, I have been looking into existing frameworks, database libraries, templating libraries and so on. Often these libraries are heavily based on macros. Now, I like very much the possibility of writing macros to get a simpler syntax than it would be possible otherwise. But it definitely adds another layer of complexity. Let me take an example of a migration in Lobos from a blog post: (defmigration add-posts-table (up [] (create clogdb (table :posts (integer :id :primary-key ) (varchar :title 250) (text :content ) (boolean :status (default false)) (timestamp :created (default (now))) (timestamp :published ) (integer :author [:refer :authors :id] :not-null)))) (down [] (drop (table :posts )))) It is very readable indeed. But it is hard to recognize what the structure is. What does the function timestamp return? Or is it a macro? Having all this freedom of writing my own syntax means that I have to learn other people's syntax for every library I want to use. How can I learn to use these components effectively? Am I supposed to learn each small DSL as a black box?

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• Progress bar in Super Hexagon using OpenGL ES 2 (Android)

  - by user16547

  I'm wondering how the progress bar in Super Hexagon was made. (see image, top left) Actually I am not very sure how to implement a progress bar at all using OpenGL ES 2 on Android, but I am asking specifically about the one used in Super Hexagon because it seems to me less straightforward / obvious than others: the bar changes its colour during game play. I think one possibility is to use the built-in Android progress bar. I can see from some Stackoverflow questions that you can change the default blue colour to whatever you want, but I'm not sure whether you can update it during the game play. The other possibility I can think of for implementing a progress bar is to have a small texture that starts with a scale of 0 and that you keep scaling until it reaches the maximum size, representing 100%. But this suffers from the same problem as before: you'll not be able to update the colour of the texture during run-time. It's fixed. So what's the best way to approach this problem? *I'm assuming he didn't use a particular library, although if he did, it would be interesting to know. I'm interested in a pure OpenGL ES 2 + Android solution.

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• OpenGL sprites and point size limitation

  - by Srdan

  I'm developing a simple particle system that should be able to perform on mobile devices (iOS, Andorid). My plan was to use GL_POINT_SPRITE/GL_PROGRAM_POINT_SIZE method because of it's efficiency (GL_POINTS are enough), but after some experimenting, I found myself in a trouble. Sprite size is limited (to usually 64 pixels). I'm calculating size using this formula gl_PointSize = in_point_size * some_factor / distance_to_camera to make particle sizes proportional to distance to camera. But at some point, when camera is close enough, problem with size limitation emerges and whole system starts looking unrealistic. Is there a way to avoid this problem? If no, what's alternative? I was thinking of manually generating billboard quad for each particle. Now, I have some questions about that approach. I guess minimum geometry data would be four vertices per particle and index array to make quads from these vertices (with GL_TRIANGLE_STRIP). Additionally, for each vertex I need a color and texture coordinate. I would put all that in an interleaved vertex array. But as you can see, there is much redundancy. All vertices of same particle share same color value, and four texture coordinates are same for all particles. Because of how glDrawArrays/Elements works, I see no way to optimise this. Do you know of a better approach on how to organise per-particle data? Should I use buffers or vertex arrays, or there is no difference because each time I have to update all particles' data. About particles simulation... Where to do it? On CPU or on a vertex processors? Something tells me that mobile's CPU would do it faster than it's vertex unit (at least today in 2012 :). So, any advice on how to make a simple and efficient particle system without particle size limitation, for mobile device, would be appreciated. (animation of camera passing through particles should be realistic)

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