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• C++ Numerical Recipes &ndash; A New Adventure!

  - by JoshReuben

  I am about to embark on a great journey – over the next 6 weeks I plan to read through C++ Numerical Recipes 3rd edition http://amzn.to/YtdpkS I'll be reading this with an eye to C++ AMP, thinking about implementing the suitable subset (non-recursive, additive, commutative) to run on the GPU. APIs supporting HPC, GPGPU or MapReduce are all useful – providing you have the ability to choose the correct algorithm to leverage on them. I really think this is the most fascinating area of programming – a lot more exciting than LOB CRUD !!! When you think about it , everything is a function – we categorize & we extrapolate. As abstractions get higher & less leaky, sooner or later information systems programming will become a non-programmer task – you will be using WYSIWYG designers to build: GUIs MVVM service mapping & virtualization workflows ORM Entity relations In the data source SharePoint / LightSwitch are not there yet, but every iteration gets closer. For information workers, managed code is a race to the bottom. As MS futures are a bit shaky right now, the provider agnostic nature & higher barriers of entry of both C++ & Numerical Analysis seem like a rational choice to me. Its also fascinating – stepping outside the box. This is not the first time I've delved into numerical analysis. 6 months ago I read Numerical methods with Applications, which can be found for free online: http://nm.mathforcollege.com/ 2 years ago I learned the .NET Extreme Optimization library www.extremeoptimization.com – not bad 2.5 years ago I read Schaums Numerical Analysis book http://amzn.to/V5yuLI - not an easy read, as topics jump back & forth across chapters: 3 years ago I read Practical Numerical Methods with C# http://amzn.to/V5yCL9 (which is a toy learning language for this kind of stuff) I also read through AI a Modern Approach 3rd edition END to END http://amzn.to/V5yQSp - this took me a few years but was the most rewarding experience. I'll post progress updates – see you on the other side !

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• Is having functionality in DB a road block to scalability?

  - by Estefany Velez

  I may not be able to give the right title to the question. But here it is, We are developing financial portal for wealth management. We are expecting over 10000 clients to use the application. The portal calculates various performance analytics based on the the technical analysis of the stock market. We developed lot of the functionality through Stored procedures, user defined functions, triggers etc. through Database. We thought we can gain huge performance boost doing stuff directly in database than through C# code. And we actually did get a huge performance boost. When I tried to brag about the achievement to our CTO, he counter questioned my decision of having functionality implemented in database rather than code. According to him such applications suffer scalability problems. In his words "These days things are kept in memory/cache. Clustered data is hard to manage over time. Facebook, Google have nothing in database. It is the era of thin servers and thick clients. DB is used only to store plain data and functionality should be completely decoupled from the database." Can you guys please give me some suggestions as to whether what he says is right. How to go about architect such an application?

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• Need help eliminating dead code paths and variables from C source code

  - by Anjum Kaiser

  I have a legacy C code on my hands, and I am given the task to filter dead/unused symbols and paths from it. Over the time there were many insertions and deletions, causing lots of unused symbols. I have identified many dead variables which were only being written to once or twice, but were never being read from. Both blackbox/whitebox/regression testing proved that dead code removal did not affected any procedures. (We have a comprehensive test-suite). But this removal was done only on a small part of code. Now I am looking for some way to automate this work. We rely on GCC to do the work. P.S. I'm interested in removing stuff like: variables which are being read just for the sake of reading from them. variables which are spread across multiple source files and only being written to. For example: file1.c: int i; file2.c: extern int i; .... i=x;

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• Which software to keep track of my project?

  - by Exa

  I'm about to start the first real phase of my game development which will consist of the acquisition of information, resources and the definition of where I want to go and what I will need for that. I just want to make sure that I'm prepared as best as possible before I actually start development. I don't like the thought of using Microsoft Word or Excel for my project management... I already worked with MS Project but I don't think it fits my needs. I need a software where I can easily maintain project steps, milestones, important issues, information about technologies and engines I use, as well as simple notes and thoughts I just want to write down. I usually prefer a whiteboard for stuff like that but unfortunately it's not a persistent way of storing. ;) Also writing it down the old-school way is something I can think of, but only for quick notes... Which software do you use for that? Are there commonly used programs? Is there any free software at all?

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• Real life example of an agile game development process outputs

  - by Ken

  I'm trying to learn about applying agile methodologies to game development. But seems to be impossible to find real life examples. There seems to be plenty of material discussing how 'in principle' agile is applied to a game. But that is NOT what I am looking for. I have the Keith book. What I AMlooking for are real EXAMPLES of things like; Initial user stories Final user stories (complete, covering the entire game requirements) Acceptance criteria Task list Sprint backlogs (before and after each sprint) The agile books seem to have some limited examples, many of which seem contrived or limited. In this era of open source software, there must be a publicly available documented example of the process applied to a real game. I am asking specifically about games because they are so different from normal applications. Regular applications are built to all users to complete specific tasks in order to get stuff done(book a room, print a report etc). People play games for much less tangible reasons, so I think the process is significantly different. [it doesn't have to be scrum, it could be any process, just needs to be a real life example game and be reasonably complete]

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• LibreOffice hangs everytime I click into it

  - by Freddy

  I've searched askubuntu for a solution but couldn't find anything helpful for me. I installed the latest version of ubuntu (13.10; 64-bit) yesterday (so I'm relatively new and unexperienced about it) and some programs as well. Today I wanted to try the LibreOffice package which comes with ubuntu by default. So I first started LO Impress, it showed me the default slide where it says something like "Add your title/text here" (I don't know exactly, I'm using my system in German). As soon as i clicked on this text, my entire system didn't react, I couldn't even click the stuff in the upper right corner (where the date, shutdown functions etc. are), nor the items on the launcher bar on the left. After 10 seconds or so, everything seemed to work properly again. But when I clicked into the LO Impress again, the same procedure as described happened again (cmpletely stuck for about 10 sec). Anybody got a solution for this? If you need more information, just tell me. Thanks in advance!

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• Php profiling on production server or other options

  - by absentx

  Alright I need some help here. I am commonly asked to speed up certain sections of some websites that I program for. I have yet to be able to figure out how to use a good php diagnosis/profiling tool. Some things to consider: The sites I am working on are already built, getting a testing server set up locally is just a huge pain..I have to rewrite include paths and just so many things. This is a results oriented deal and spending days to get a site fully working on a testing platform so I can debug one page probably isn't an option. I can write tons of php, but I have no clue how to interact or mess with servers. So every tutorial I read about setting up xdebug or xhprof all seem to involve getting something installed on a production server that I don't have access to or have no clue how to work with. So are there any solutions out there that will show me where my php is slow without having to do all sorts of server stuff that I just don't know how to do? Xhprof seems to be the closest to useable for me but from what I can tell it still has to be installed on a server. If anyone can just point me in the right direction on this I would be very grateful. Maybe getting these things put on the server isn't a big deal...but I have never interacted with server command lines or anything like that. I suppose I should start sometime but I really have no idea where to start. Plus I realize that profiling on a live platform is not the greatest idea either but I feel I am in a tough spot. I have speed issues to solve and setting up a local environment while a great idea, just doesn't seem real practical at the moment.

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• Missing Package: header, Problem with MergeList, The package lists or status file could not be parsed or opened

  - by Inbar Rose

  THIS IS NOT A DUPLICATE OF SIMILAR QUESTIONS (like this) I just had to write that first, there are tons of questions similar to this, all of them have the same redirect to an answer that does not solve my problem, because I don't have the same problem, just the same symptom. I write tests for my companies application. One of these tests tries to upgrade the application from a previous version to a new version to make sure nothing breaks. When I am installing an old version of the application, some weird stuff starts to happen. Sometimes everything goes Okay, and nothing is wrong, other times when trying to install I get this message (company app name censored): E: Encountered a section with no Package: header E: Problem with MergeList /var/lib/apt/lists/XXX-amd64_Packages E: The package lists or status file could not be parsed or opened. Using the solutions provided in the questions similar to this one (like this). Do not help, and the problem keeps repeating itself once it happens the first time. This has led me to believe something is wrong on the apt server where the package is being created, but searching these errors yields no information on anything beyond the "fix" suggested in the question I linked, the only other source of information I could find also did not help (here): So I am asking for information; What is the actual problem? What causes the problem? What can fix the problem? I hope this question is in good format, if there is a problem, or missing information I can move to chat.

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• Looking for a small, light scene graph style abstraction lib for shader based OpenGL

  - by Pris

  I'm looking for a 'lean and mean' c/c++ scene graph library for OpenGL that doesn't use any deprecated functionality. It should be cross platform (strictly speaking I just dev on Linux so no love lost if it doesn't work on Windows), and it should be possible to deploy to mobile targets (ie OpenGLES2, and no crazy mandatory dependencies that wouldn't port well to modern mobile frameworks like iOS, Android, etc), with a license that's compatible with closed source software (LGPL or more liberal). Specific nice-to-haves would be: Cameras and Viewers (trackball, fly-by, etc) Object transform hierarchies (if B is a child of A, and you move A, B has the same transform applied to it) Simple animation Scene optimization (frustum culling, use VBOs, minimize state changes, etc) Text I've played around with OpenSceneGraph a lot and it's pretty amazing for fixed function pipeline stuff, but I've had a few of problems using it with the programmable pipeline and after going through their mailing list, it seems several people have had similar issues (going back years). Kitware's VES looks neat (http://www.vtk.org/Wiki/VES), but VES + VTK is pretty heavy. VTK is also typically for analyzing scientific data and I've read that it's not that appropriate for a general use case (not that great at rendering a lot of objects on scene,etc) I'm currently looking at VisualizationLibrary (http://www.visualizationlibrary.org/documentation/pag_gallery.html) which looks like it offers some of the functionality I'd like, but it doesn't explicitly support mobile targets. Other solutions like Ogre, Horde3D, Irrlicht, etc tend to be full on game engines and that's not really what I'm looking for. I'd like some suggestions for other libraries that I may have missed... please note I'm not willing to roll my own solution from scratch.

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• Compressing 2D level data

  - by Lucius

  So, I'm developing a 2D, tile based game and a map maker thingy - all in Java. The problem is that recently I've been having some memory issues when about 4 maps are loaded. Each one of these maps are composed of 128x128 tiles and have 4 layers (for details and stuff). I already spent a good amount of time searching for solutions and the best thing I found was run-length enconding (RLE). It seems easy enough to use with static data, but is there a way to use it with data that is constantly changing, without a big drop in performance? In my maps, supposing I'm compressing the columns, I would have 128 rows, each with some amount of data (hopefully less than it would be without RLE). Whenever I change a tile, that whole row would have to be checked and I'm affraid that would slow down too much the production (and I'm in a somewhat tight schedule). Well, worst case scenario I work on each map individually, and save them using RLE, but it would be really nice if I could avoind that. EDIT: What I'm currently using to store the data for the tiles is a 2D array of HashMaps that use the layer as key and store the id of the tile in that position - like this: private HashMap< Integer, Integer [][]

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• How do I get Graphics drivers / bluetooth / card reader working on an Acer Aspire V3-571G?

  - by Adam

  A couple of days ago I bought an Acer Aspire V3-571G laptop without a system installed on it. The only thing that was there was Linux Linpus. I created a bootable CD with Ubuntu 12.04 64-bit - I read that my processor was 64 bit and that it might be a good configuration for my gear (I'm not especially fluent with all the computer stuff, still trying to learn) and replaced Linpus with Ubuntu. Everything seemed to work fine, but there're few exceptions to that which came pass my way. My bluetooth doesn't work. It seems to be switched on, but when I check my system settings the button is actually off, and I can't drag it 'perminently' to the 'on' position. Tried a couple of commands I found on the net, none of them helped and there was no word whatsoever in my BIOS settings about enabling bluetooth. My card reader has some serious problems with copying more than one file at a time. I tried to put some music on my phone through a MicroSD card adapter (because my bluetooth doesn't work) and it got stuck every single time I copied an album on it. I'm not sure if all my drivers were properly installed, so I checked in the terminal if it could tell me sth about my graphics. typed: sudo lshw -c display and what i got was: *-display UNCLAIMED description: VGA compatible controller product: NVIDIA Corporation vendor: NVIDIA Corporation physical id: 0 bus info: pci@0000:01:00.0 version: a1 width: 64 bits clock: 33MHz capabilities: pm msi pciexpress vga_controller cap_list configuration: latency=0 resources: memory:b2000000-b2ffffff memory:a0000000-afffffff memory:b0000000-b1ffffff ioport:2000(size=128) *-display description: VGA compatible controller product: Ivy Bridge Graphics Controller vendor: Intel Corporation physical id: 2 bus info: pci@0000:00:02.0 version: 09 width: 64 bits clock: 33MHz capabilities: msi pm vga_controller bus_master cap_list rom configuration: driver=i915 latency=0 resources: irq:44 memory:b3000000-b33fffff memory:c0000000-cfffffff ioport:3000(size=64) As I said I'm no expert and not english-speaking generally, but it doesn't seem to be right. I've got a NVIDIA GeForce GT 640M.

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• Basics of Website development [closed]

  - by user975234

  I have read this post: What should every programmer know about web development? but I have some more questions... I will be developing a content related website very soon and I am confused about some technology stuff. I am thinking about developing the site using ruby on rails. So when I'll be buying hosting, do I need to ask for something special? Like for example, we need to specify what kind of hosting we need, windows or linux. So for ruby on rails do I need some extra facilities from the hosting provider? Is ruby on rails a good choice for a large content related website? This may be a bit stupid but how do I choose my backend, scripting languages etc? Thing is I am really new to website development. And the flow of making websites is not clear. Any links will be helpful. EDIT: I know this question has been voted as non constructive. But if any one still has some precise knowledge about how the flow of website development goes, please comment your views.. That will be helpful!

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• Most effective work habit for coding? [on hold]

  - by Cris

  Working on a big solo project (~15,000 LOC), I am encountering the following phenomenon: I seem to work best when I program in short bursts of 10-15 minutes. Right now I am working on a section which is a complete first time for me architecturally and if I have any architectural issues that emerge when doing the implementation, I seem to be able to best serve these by taking a total break. Then, later, sketching out the ideas on some paper. And when I feel I have sufficient clarity, then going back to code. This iterates until that architectural issue for that section is resolved. This seems quite counter intuitive: that I can progress more quickly by coding less, and taking more breaks. I am nearing the end of the sections which are "first times" for me, and about to dive into stuff which I am much more familiar and am wondering if this counter intuitive efficiency will continue. So my question is: even for regular coding of sections one is familiar with, which don't require constant re-clarification of the best architecture, is more progress to be attained by taking more breaks and coding in bursts?

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• How to break the "php is a bad language" paradigm? [closed]

  - by dukeofgaming

  PHP is not a bad language (or at least not as bad as some may suggest). I had teachers that didn't even know PHP was object oriented until I told them. I've had clients that immediately distrust us when we say we are PHP developers and question us for not using chic languages and frameworks such as Django or RoR, or "enterprise and solid" languages such as Java and ASP.NET. Facebook is built on PHP. There are plenty of solid projects that power the web like Joomla and Drupal that are used in the enterprise and governments. There are frameworks and libraries that have some of the best architectures I've seen across all languages (Symfony 2, Doctrine). PHP has the best documentation I've seen and a big community of professionals. PHP has advanced OO features such as reflection, interfaces, let alone that PHP now supports horizontal reuse natively and cleanly through traits. There are bad programmers and script kiddies that give PHP a bad reputation, but power the PHP community at the same time, and because it is so easy to get stuff done PHP you can often do things the wrong way, granted, but why blame the language?. Now, to boil this down to an actual answerable question: what would be a good and solid and short and sweet argument to avoid being frowned upon and stop prejudice in one fell swoop and defend your honor when you say you are a PHP developer?. (free cookie with teh whipped cream to those with empirical evidence of convincing someone —client or other— on the spot) P.S.: We use Symfony, and the code ends being beautiful and maintainable

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• How to get httpd to forward to multiple tomcats for different urls, including / ?

  - by Nick Foote

  Ok So I've got multiple tomcat instances setup on several AJP ports, I also have Apache httpd listening on port 8090 (cos I've got another app already using 8080 at the moment). I've successfully mapped urls such as mydomain.com:8090/demo and mydomain.com:8090/preprod to their respective tomcat instances using Jk Mount and the following vhosts config; <VirtualHost *:8090> JkMount /preprod* preprod JkMount /demo* demo </VirtualHost> But I also want the "root" address to map to another tomcat instance, what will become live/production, ie I want mydomain.com:8090/ to map a 3rd tomcat instance. At the moment nothing happens or changes if I just add to the above config a line; JkMount /* rootwar if I browse to mydomain.com:8090 I just get the same boring apache httpd landing page letting me know its running (ie index.html in httpd/htdocs) Is it possible to use JkMount to redirect the "root" address stuff to a tomcat instance? I can see that a rule like /* will also match URLs like mydomain.com/preprod but I was hoping the rules are applied in order so if /* appears at the end it effectively would be a "if its not one of the other environments, then direct to root/production" Just to be clear I'm trying to setup the following; mydomain.com:8090/preprod --> myApp running in tomcat1 mydomain.com:8090/demo --> myApp running in tomcat2 mydomain.com:8090 --> myApp running in tomcat3

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• looking for a short explanation of fuzzy logic

  - by user613326

  Well i got the idea that basics of fuzzy logic are not that hard to grasp. And i got the feeling that someone might explain it to me in like 30 minutes. Just like i understand neural networks and am able to re-create the famous Xor problem. And go just beyond it and create 3 layer networks of x nodes. I'd like to understand fuzzy till a similar usefully level, in c# language. However the problem is face, I'd like to get concept right however i see many websites who include lots of errors in their basic explaining. Like for example showing pictures and use different numbers as shown in pictures to calculate, as if lots of people just copied stuff without noticing what they write down. While others for me go to deep in their math notation) To me that's very annoying to learn from. For me there is no need to re-invent wheel; Aforge already got a fuzzy logic framework. So what i am looking for are some good examples, good examples like how the neural XOR problem is solved. Is there anyone such a instructional resource out there; do you know a web page, or YouTube where it is shortly explained, what would you recommend me ? Note this article comes close; but it just doesnt nail it for me. After that i downloaded a bunch of free PDF's but most are academic and hard to read for me (i'm not English and dont have a special math degree). (i've been looking around a lot for this, good starter material about it is hard to find).

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• Install GRUB to Ubuntu Partition

  - by Noel

  So my computer has the following partitions: /dev/sda -- (I know this isn't a real partition, but more so the boot loader) /dev/sda1 -- (Windows 7 Boot Loader) /dev/sda3 -- (Windows 7) /dev/sda4 -- (Data partition, NTFS) that means i have /dev/sda2 as free space. I do not want to change the MBR of the computer. I would like /dev/sda2 to contain GRUB AND Ubuntu. So ideally when I turn my computer on, BIOS would ask if I'd like to boot Windows 7 or Ubuntu(or Grub or partition 2), and I could choose either one. But I would like Grub and Ubuntu to be on the same partition, so they will not interfere in any way with windows or window's boot loader/partition (sda3) How can I do this? Catch: when formatting partitions, Ubuntu does not give me the option to make them virtual partitions, so that makes things harder. I tried: installing Ubuntu to /dev/sda2 (which I formatted as ext4) and then told the Ubuntu installer to install the bootloader to /dev/sda2. But when I select "Ubuntu" from BIOS's boot selection, it loads a black screen and says "invalid arch independent ELF magic grub rescue _" and allows me to input stuff. How can I fix this, or tell my computer where Grub is?

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• HTG Explains: What Are Computer Algorithms and How Do They Work?

  - by YatriTrivedi

    Unless you’re into math or programming, the word “algorithm” might be Greek to you, but it’s one of the building blocks of everything you’re using to read this article. Here’s a quick explanation of what they are, and how they work. Disclaimer: I’m not a math or computer science teacher, so not all of the terms I use are technical. That’s because I’m trying to explain everything in plain English for people aren’t quite comfortable with math. That being said, there is some math involved, and that’s unavoidable. Math geeks, feel free to correct or better explain in the comments, but please, keep it simple for the mathematically disinclined among us. Image by Ian Ruotsala Latest Features How-To Geek ETC How To Make Hundreds of Complex Photo Edits in Seconds With Photoshop Actions How to Enable User-Specific Wireless Networks in Windows 7 How to Use Google Chrome as Your Default PDF Reader (the Easy Way) How To Remove People and Objects From Photographs In Photoshop Ask How-To Geek: How Can I Monitor My Bandwidth Usage? Internet Explorer 9 RC Now Available: Here’s the Most Interesting New Stuff Lucky Kid Gets Playable Angry Birds Cake [Video] See the Lord of the Rings Epic from the Perspective of Mordor [eBook] Smart Taskbar Is a Thumb Friendly Android Task Launcher Comix is an Awesome Comics Archive Viewer for Linux Get the MakeUseOf eBook Guide to Speeding Up Windows for Free Need Tech Support? Call the Star Wars Help Desk! [Video Classic]

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• ImageResizer - AzureReader2 with Azure SDK 2.2

  - by Chris Skardon

  Originally posted on: http://geekswithblogs.net/cskardon/archive/2013/10/29/imageresizer---azurereader2-with-azure-sdk-2.2.aspxSo Azure SDK 2.2 came out recently, which means I can open my azure projects in VS 2013 (yay), so I decided to do an upgrade of my MVC4 project to MVC5, I followed this link on how to do the upgrade, and generally things went ok. I fire up my app, and run into a ‘binding’ issue, that AzureReader2 was trying to use Microsoft.WindowsAzure.Storage, Version=2.1.0.0 but alas, it couldn’t find it. I am not the only one (see stackoverflow), and one solution is to run ‘Add-BindingRedirect’ from the Package Manager Console, but that didn’t solve the problem for me, as it didn’t pick up on the Azure stuff, so I resorted to adding the redirect manually. So, in short, to get AzureReader2 to work with Azure SDK 2.2, you need to add the following to your web.config: <runtime> <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1"> <!-- Other bindings here! --> <dependentAssembly> <assemblyIdentity name="Microsoft.WindowsAzure.Storage" publicKeyToken="31bf3856ad364e35" culture="neutral"/> <bindingRedirect oldVersion="0.0.0.0-2.1.0.3" newVersion="2.1.0.3"/> </dependentAssembly> </assemblyBinding>

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• Where to go after having a good grasp of a language?

  - by Alex M.

  I have been programming as a hobby for the past few years now (most of high school and 1 year in cs in college) and although I've came to the conclusion that a career in CS isn't for me I switched over to math (which pairs what I love about programming with my interest in physical sciences) but I miss writing code. Recently I've had an interest in low-level programming. Understanding how compilers work, learning some basics of assembly language and trying to get out of my comfort zone. The problem is that since I've been out of the CS programs, I'm not faced with much opportunities to write code. I do intend to take a few CS classes in college (a lot of CS stuff is opened to math majors) but that won't come for until next year. So I ask: What are the steps to take in order to keep improving as a programmer once you're passed the basic steps? How do you find projects to keep you going? Beside my newly discovered interest in assembly language, I've been writing code in C and have been interested in FOSS. Thanks!

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• Rope Colliding with a Rectangle

  - by Colton

  I have my rope, and I have my rectangles. The rope is similar to the implementation found here: http://nehe.gamedev.net/tutorial/rope_physics/17006/ Now, I want to make the rope properly collide with the rectangle such that the rope will not pass through a rectangle, and wrap around the rectangle and all that good stuff. Currently, I have it set so no rope node can pass through a rect (successfully), however, this means a rope segment can still pass through a block. Ex: So the question is, what can I do to fix this? What I have tried: I create a rectangle between two nodes of a rope, calculate rotation between the nodes, and get myself a transformed rectangle. I can successfully detect a collision between rope segments and a (non-transformed) rectangle. Create a new node or pivot point around the corner of the block, and rearrange nodes to point to the corner node. Trouble is determining what corner the rope segment is passing through. And then the current rope setup goes wonky (based on verlet integration, so a sudden change in position causes the rope to wiggle like a seismograph during a magnitude 8 earth quake.) Among other issues that might be solvable, but its turning into a case by case thing, which doesn't seem right. I think the best answer here would just be a link to a tutorial (I simply can't find any, most lead to box2D or farseer, but I want to at least learn how it works before I hide behind an engine).

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• RPi and Java Embedded GPIO: Hooking Up Your Wires for Java

  - by hinkmond

  So, you bought your blue jumper wires, your LEDs, your resistors, your breadboard, and your fill of Fry's for the day. How do you hook this cool stuff up to write Java code to blink them LEDs? I'll step you through it. First look at that pinout diagram of the GPIO header that's on your RPi. Find the pins in the corner of your RPi board and make sure to orient it the right way. The upper left corner pin should have the characters "P1" next to it on the board. That pin next to "P1" is your Pin #1 (in the diagram). Then, you can start counting left, right, next row, left, right, next row, left, right, and so on: Pins # 1, 2, next row, 3, 4, next row, 5, 6, and so on. Take one blue jumper wire and connect to Pin # 3 (GPIO0). Connect the other end to a resistor and then the other end of the resistor into the breadboard. Each row of grouped-together holes on a breadboard are connected, so plug in the short-end of a common cathode LED (long-end of a common anode LED) into a hole that is in the same grouping as where the resistor is plugged in. Then, connect the other end of the LED back to Pin # 6 (GND) on the RPi GPIO header. Now you have your first LED connected ready for you to write some Java code to turn it on and off. (As, extra credit you can connect 7 other LEDs the same way to with one lead to Pins # 5, 7, 11, 13, 15, 19 & 21). Whew! That wasn't so bad, was it? Next blog post on this thread will have some Java source code for you to try... Hinkmond

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• How do I choose which way to enable/disable, start/stop, or check the status of a service?

  - by Glyph

  If I want to start a system installed service, I can do: # /etc/init.d/some-svc start # initctl start some-svc # service some-svc start # start some-svc If I want to disable a service from running at boot, I can do: # rm /etc/rc2.d/S99some-svc # update-rc.d some-svc disable # mv /etc/init/some-svc.conf /etc/init/some-svc.conf.disabled Then there are similarly various things I can do to enable services for starting at boot, and so on. I'm aware of the fact that upstart is a (relatively) new thing, and I know about how SysV init used to work, and I'm vaguely aware of a bunch of D-Bus nonsense, but what I don't know is how one is actually intended to interface with this stuff. For example, I don't know how to easily determine whether a service is an Upstart job or a legacy SysV thing, without actually reading through the source of its shell scripts extensively. So: if I want to start or stop a service, either at the moment or persistently, which of these tools should I use, and why? If the answer depends on some attribute (like "this service supports upstart") then how do I quickly and easily learn about that attribute of an installed package? Relatedly, are there any user interface tools which can safely and correctly interact with the modern service infrastructure (upstart, and/or whatever its sysv compatibility is)? For example, could I reliably use sysv-rc-conf to determine which services should start?

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• Operating System not Found after installing Ubuntu in a Sony Vaio

  - by diego8arock

  I just bought a Sony Vaio SVS15115FLB that came with Windows 7, after enjoying the PC graphic power for a little, I decided it was time to install Ubuntu 12.04. First, I inserted a USB stick, reboot, press F11 but a message saying that no OS was found on the USB, so then I used a live CD. It booted fine and I installed Ubuntu, then when it was time to restart the PC, it didn't boot to GRUB but it went straight to Windows and it began an startup error and was looking for a solution, after it was done, it restarted and then it booted again to Windows and to the same start up error solution thing. I freaked out, so I booted again the Ubuntu live CD, and installed Ubuntu over everything, after it installed I rebooted and then a message appeared saying Operating system Not Found, and I have no idea why. So I Googled again and found this post on Boot Partition, I did everything exactly on that post, but it didn't work (by the way, this was the message): The boot files of [Ubuntu 12.04 LTS] are far from the start of the disk. Your BIOS may not detect them. You may want to retry after creating a /boot partition (EXT4, >200MB, start of the disk). This can be performed via tools such as gParted. Then select this partition via the [Separate /boot partition:] option of [Boot Repair]. It appeared the first time, then I did it all again and then it was gone. I rebooted and nothing, the same Operating System not found message appeared. So I decided to create a partition for Windows, hoping for something, but the message still appears. I really have no idea what to do, but there is something odd, if I insert the USB stick containing Ubuntu 11.10, the message that says that there is no OS in the PendDrive flashes for a fraction of a second and the boot straight to Ubuntu 12.04 without problems (and booted to Windows when I installed it, ignoring Ubuntu), right now I'm using it like that, but its pretty annoying. Can anyone advise me how to fix this? I'm no expert on this kind of things (boot, GRUB, recovery and stuff like that).

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• What did you learn today?

  - by Rajesh Pillai

  What did you learn today? Everyday teaches you something, some lesson or the other. Some day you learn a new language, a new skill or a new hobby or visit some new place, learn music, have a different dining experience, learn swimming, make some good friends, get in touch with some old friend etc. etc…. Each of these things teaches you something… So, what did you learn today? Some of the learnings from my past weeks are outlined below… Respect others. Don’t underestimate them. (Though I never consciously do so) Be careful with your words because words have different meanings if the context is not clear. Spend some time for your personal stuff and allow others do so. Every individual is different, their skills different, their thoughts are different, their perceptions are different. So, be polite. Time management. (This is a tough skill to master). At the end of the day I keep looking for more time so may be you. So, again What did you learn today? This reflection is important because if you don’t know what you are learning at every stage in your life, then your are not learning and not growing. In short you are not living. Learning is not memorization but it is self realization….. Happy learning!!!

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