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  • How to suggest changes as a recently-hired employee ?

    - by ereOn
    Hi, I was recently hired in a big company (thousands of people, to give an idea of the size). They said they hired me because of my rigor and because I was, despite my youngness (i'm 25), experienced as a C/C++ programer. Now that I'm in, I can see that the whole system is old and often uses obsolete technologies. There is no naming convention (files, functions, variables, ...), they don't use Version Control, don't use exceptions or polymorphism and it seems like almost everybody lost his passion (some of them are only 30 years old). I'd like to suggest somes changes but i don't want to be "the new guy that wants to change everything just because he doesn't want to fit in". I tried to "fit in", but actually, It takes me one week to do what I would do in one afternoon, just because of the poor tools we're forced to use. A lot my collegues never look at the new "things" and techniques that people use nowadays. It's like they just given up. The situation is really frustrating. Have you ever been in a similar situation and, if so, what advices would you give me ? Is there a subtle way of changing things without becoming the black sheep here ? Or should I just give up my passion and energy as well ? Thank you. Updates Just in case (if anyone cares): following your precious advices I was able to suggest changes and am now in charge of the team that must create and deploy Subversion :D Thanks to all of you !

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  • Storing Tiled Level Data in J2ME game

    - by Alex
    I'm developing a J2ME game which uses tiled backgrounds for the levels. My question is how do I store this tile information in my game. At the moment it is stored as an array; with each number representing a different tile from the tile-sheet. This works well enough, however I don't like the fact that it is 'hard-coded' into the game because (at least in my opinion) it is harder to edit the levels, or design new ones. I was also thinking that it would be difficult if you wanted to add a 'level pack', I'm not sure on how this would be achieved though; it's not something I was planning on doing, I'm just curious. I was wondering if there was a way I could store level data in some external file and then load this in to the game. The problem is I don't know what the limitations are for J2ME regarding file I/O, can it read in any file like Java? I am aware of the RMS, but from my experience I don't think this would work (unless I am mistaken). Also, would loading the data in this way be too big a performance hit? Or is there another way I can achieve what I am trying to do. As I said, the way I have it at the moment works fine, and if this is the only viable option then it will suffice.

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  • Floating point undesirable in highly critical code?

    - by Kirt Undercoffer
    Question 11 in the Software Quality section of "IEEE Computer Society Real-World Software Engineering Problems", Naveda, Seidman, lists fp computation as undesirable because "the accuracy of the computations cannot be guaranteed". This is in the context of computing acceleration for an emergency braking system for a high speed train. This thinking seems to be invoking possible errors in small differences between measurements of a moving object but small differences at slow speeds aren't a problem (or shouldn't be), small differences between two measurements at high speed are irrelevant - can there be a problem with small roundoff errors during deceleration for an emergency braking system? This problem has been observed with airplane braking systems resulting in hydroplaning but could this actually happen in the context of a high speed train? The concern about fp errors seems to not be well-founded in this context. Any insight? The fp is used for acceleration so perhaps the concern is inching over a speed limit? But fp should be just fine if they use a double in whatever implementation language. The actual problem in the text states: During the inspection of the code for the emergency braking system of a new high speed train (a highly critical, real-time application), the review team identifies several characteristics of the code. Which of these characteristics are generally viewed as undesirable? The code contains three recursive functions (well that one is obvious). The computation of acceleration uses floating point arithmetic. All other computations use integer arithmetic. The code contains one linked list that uses dynamic memory allocation (second obvious problem). All inputs are checked to determine that they are within expected bounds before they are used.

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  • Is it possible to generate Events and Hooks in Lua for any game without built-in support?

    - by pr0tocol
    Does a game have to have built-in functions to accept and run lua scripts, or can I design Events and Hooks using Lua on any game I please, akin to the days where C code could be used to hook into the WinAPI using dlls? The reason I ask is, I am trying to create a background application that will perform events and hooks on a particular game that does not currently support lua in-game. Brief examples: Events: - An action executed by the PLAYER is detected. For instance, hitting the Q key will normally make my character use an ability, but with my Lua script running in the background, will cause a sound to play on my computer (or something). Hooks: - An action within the GAME is detected. For instance, the game spawns an enemy every minute. When an enemy spawns, the script will detect this and perform an action, for instance playing a sound locally on the computer. I would like to do both, but I know for games like Garry's Mod, the game already has built-in support for running lua scripts. Is there a way to do either events OR hooks using lua similarly to how C/C++ can connect to a game using WinAPI dlls?

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  • How should a JEE application store credentials for logging in to an external system?

    - by FGreg
    I am in a situation where I have a Web Application (WAR) that is accessing a REST service provided by another application. The REST service uses Basic HTTP Authentication. So that means the application calling the REST service needs to store user credentials somehow. To further complicate things, this is an enterprise, so there are different 'regions' the application moves through which will have different credentials for the same service (think local development, development region, integration region, user test region, production, etc...) My first instinct is that the credentials should be stored by the JEE container and the application should ask the container for the credentials (probably via JNDI?). I'm beginning to read about Java Authentication and Authorization Service (JAAS) but I'm not sure if that is the appropriate solution to this problem. How should a JEE application store credentials for logging in to an external system? A few more details about my WAR. It is a Spring-Integration project that has no front-end. The container I am working with is Websphere. I am using JEE 5 and Spring 4.0.1. To this point I have not needed to consider spring-security... does this situation mean I should re-evaluate that decision?

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  • How can I read a portion of one Minecraft world file and write it into another?

    - by RapierMother
    I'm looking to read block data from one Minecraft world and write the data into certain places in another. I have a Minecraft world, let's say "TemplateWorld", and a 2D list of Point objects. I'm developing an application that should use the x and y values of these Points as x and z reference coordinates from which to read constant-sized areas of blocks from the TemplateWorld. It should then write these blocks into another Minecraft world at constant y coordinates, with x & z coordinates determined based on each Point's index in the 2D list. The issue is that, while I've found a decent amount of information online regarding Minecraft world formats, I haven't found what I really need: more of a breakdown by hex address of where/what everything is. For example, I could have the TemplateWorld actually be a .schematic file rather than a world; I just need to be able to read the bytes of the file, know that the actual block data starts always at a certain address (or after a certain instance of FF, etc.), and how it's stored. Once I know that, it's easy as pie to just read the bytes and store them.

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  • Serializing network messages

    - by mtsvetkov
    I am writing a network wrapper around boost::asio and was wondering what is a good and simple way to serialize my messages. I have a message factory which can take care of dispatching the data to the correct builder, but I want to know if there are any established solutions for getting the binary data on the sender side and consequently passing the data for deserialization on the receiver end. Some options I've explored are: passing a pointer to a char[] to the serialize/deserialize functions (for serialize to write to, and deserialize to read from), but it's difficult to enforce buffer size this way; building on that, I decided to have the serialize function return a boost::asio::mutable_buffer, however ownership of the memory gets blurred between multiple classes, as the network wrapper needs to clean up the memory allocated by the message builder. I have also seen solutions involving streambuf's and stringstream's, but manipulating binary data in terms of its string representation is something I want to avoid. Is there some sort of binary stream I can use instead? What I am looking for is a solution (preferrably using boost libs) that lets the message builder dictate the amount of memory allocated during serialization and what that would look like in terms of passing the data around between the wrapper and message factory/message builders. PS. Messages contain almost exclusively built-in types and PODs and form a shallow but wide hierarchy for the sake of going through a factory. Note: a link to examples of using boost::serialization for something like this would be appreciated as I'm having difficulties figuring out the relation between it and buffers.

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  • Is there an idiot's guide to software licensing somewhere?

    - by Karpie
    Basically, my knowledge on the issue is zilch other than the fact that open-source and closed-source exists. I'm a web developer (not a designer in the slightest), so I look online for things like icons. I've always been a big fan of these icons, which have a Creative Commons Attribution 2.5 License. As far as I can see, this license says 'do whatever you want with them as long as you have a link back to me somewhere'. Is that assumption correct? Just today I found a new icon set, with a much more confusing license (found here), and to be quite honest I have no idea if I'm allowed to use them or not. At the moment I want to just use them for toy stuff that might never see the light of day, but then my source code is stored on Github, is it legal to store the icons there where they're publicly accessible? If I put them on my personal website that might have ads on it to make me five cents every now and then, is that legal? If I use them on a site that offers a free service to users, is that legal? If that site then starts making money (via things like paid subscriptions) or gets bought out by someone (highly unlikely but one day possible) is that legal? Is there some noob guide out there that explains all this stuff, because I would hate to start using this sort of stuff now only to have to change it all later. Even if I buy the icons, there's still licensing issues that I don't understand! :( And this sort of stuff keeps popping up more and more often...

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  • How to configure KDE default settings for a new user of a group?

    - by Adobe
    I'm a sys admin on Kubuntu 11.10 machine. Where do I configure the basic config for a new user (say belonging to group "users")? Edit 1: I want to configure langauages - currently my new users get English and Bulgarian Languages. I want them to get English and Russian - and also to set Alt-CapsLock - to be the input-language-switching-combination. Edit 2: How do I configure things in /usr/share/kde4 When I do kdesudo systemsettings and save configurations - only root settings got changed - not the /usr/share/kde4 ones. Edit 3: New user gets the /etc/skel files controlling bash behaviour-appearence. What about the KDE new user's default files - where are they stored? Edit 4: Oh, I found some hints: kde4-config --path config gives a list of folders (separated by the colon) where KDE looks for configs. My machine responded with: /home/boris/.kde/share/config/ /etc/kde4/ /usr/share/kubuntu-default-settings/kde4-profile/default/share/config/ /usr/share/kde4/config/ /usr/share/desktop-base/profiles/kde-profile/share/config/ It looks like third line is where KDE takes the default options. So I found these zilions of settings - but no GUI way to configure it ((. Edit 5: Finally, I've created a dummy user, configured it, and wrote a script which gives it's settings to a given user(s). The trick - is to chown after one transfered the dot files from one user to another. I've tested it - it works fine.

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  • What is the difference between the "Entire Partition" and "Entire Disc"?

    - by Roman
    I want to install Ubuntu alongside my Windows 7 operation system. During installation I have three options: Install alongside the existing OS. Remove everything and install Ubuntu. Manual partitioning (advanced). The above list is not precise (I do not remember what exactly was written there and I just write options as I have understood them). I know that option 2 is not mine. So, I need to choose either 1 or 3. I do not know which one I need to choose. I want to have a possibility to manually specify space assigned to Windows and Ubuntu (for example 40% for Windows and 60% for Ubuntu). I chose the 1st option and I saw a window with the following information. Allocate drive space by dragging the drive bellow. File (48.1 GB) Ubuntu /dev/sda2 (ntfs) /dev/sda3 (ext4) 286.6 GB 241.7 GB 2 small partitions are hidden, use the advanced partitioning tool for more control. [use entire partition] [use entire disk] [Quit] [Back] [Install Now] My problem is that I do not understand what I see. In particular I can press [use entire partition] or [use entire disk] and I do not know what is the difference. Moreover, as far as I understand, I can even press [Install Now] without pressing one of the two above mentioned buttons. So, I have 3 options. What is the difference between them? The most important thing for me is not to delete the old operation system with all the data stored there.

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  • How to Integrate Dropbox with Pages, Keynote, and Numbers on iPad

    - by The Geek
    The iWork apps are some of the best apps on the iPad, and each show just how powerful a touchscreen device can be with the most basic of computing functions. In fact, there’s not much to dislike about the iWork apps, except for one thing: importing and exporting files. You can open documents from email attachments, download them from websites, or import them from other apps like Dropbox. Once you’ve opened your file in Pages, Keynote, or Numbers on iPad, though, you can only send it via email, upload it to a WebDAV server or Apple’s iDisk service, or wait to sync it with iTunes on your computer. Most other iOS office apps don’t offer nearly as many features as the iWork apps, but they do offer deep integration with Dropbox which makes it easy to view and edit your documents no matter where you are. Dropbox is the most popular file sync and sharing solution, and makes it absolutely painless to share folders with anyone around the world and keep your computers in sync. That is, computers and applications that integrate with Dropbox. However, you don’t need to give up on using Dropbox with iWork apps on iPad. Today we’re going to look at how you can enable WebDAV compatibility on your Dropbox account to let Pages integrate nearly the whole way with Dropbox. It’s not a perfect solution, but it’s much better than the default setup. So let’s get started Latest Features How-To Geek ETC How to Integrate Dropbox with Pages, Keynote, and Numbers on iPad RGB? CMYK? Alpha? What Are Image Channels and What Do They Mean? How to Recover that Photo, Picture or File You Deleted Accidentally How To Colorize Black and White Vintage Photographs in Photoshop How To Get SSH Command-Line Access to Windows 7 Using Cygwin The How-To Geek Video Guide to Using Windows 7 Speech Recognition Stylebot Customizes Web Pages in Chrome, Now Has Downloadable Styles Blackberry, Dell, Apple, and Motorola Tablets Compared [Infographic] Encrypt Your Google Search Queries Vintage Posters Showcase the History of Tech Advertising Google Cloud Print Extension Lets You Print Doc/PDF/Txt Files from Web Sites Hack a $10 Flashlight into an Ultra-bright Premium One

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  • What is a 'good number' of exceptions to implement for my library?

    - by Fuzz
    I've always wondered how many different exception classes I should implement and throw for various pieces of my software. My particular development is usually C++/C#/Java related, but I believe this is a question for all languages. I want to understand what is a good number of different exceptions to throw, and what the developer community expect of a good library. The trade-offs I see include: More exception classes can allow very fine grain levels of error handling for API users (prone to user configuration or data errors, or files not being found) More exception classes allows error specific information to be embedded in the exception, rather than just a string message or error code More exception classes can mean more code maintenance More exception classes can mean the API is less approachable to users The scenarios I wish to understand exception usage in include: During 'configuration' stage, which might include loading files or setting parameters During an 'operation' type phase where the library might be running tasks and doing some work, perhaps in another thread Other patterns of error reporting without using exceptions, or less exceptions (as a comparison) might include: Less exceptions, but embedding an error code that can be used as a lookup Returning error codes and flags directly from functions (sometimes not possible from threads) Implemented an event or callback system upon error (avoids stack unwinding) As developers, what do you prefer to see? If there are MANY exceptions, do you bother error handling them separately anyway? Do you have a preference for error handling types depending on the stage of operation?

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  • Ubuntu 12.04 resolution stuck on 640x480

    - by user212483
    I am new to Ubuntu and I was trying to get my HDMI enabled TV to work with my Ubuntu 12.04 computer and I installed a Nvidia driver using the "additional drivers" program. After that didn't work, I started playing around with the dual booted windows 7 on my computer. Now, I've never used that windows since I installed it so I was stripped down to bare minimum so I tried to adjust the resolution(as it was on lowest resolution) and tried to connect the HDMI, which didn't work. After that I came back to my Ubuntu installation only to find out that it is now stuck on 640x480 resolution. I tried to remove the driver that I installed again using the "additional drivers" program but that didn't help at all. The error that showed up was - Could not apply the stored configuration for monitors none of the selected modes were compatible with the possible modes: Trying modes for CRTC 63 CRTC 63: trying mode 640x480@60Hz with output at 1366x768@60Hz (pass 0) CRTC 63: trying mode 640x480@60Hz with output at 1366x768@60Hz (pass 1) Trying modes for CRTC 64 CRTC 64: trying mode 640x480@60Hz with output at 1366x768@60Hz (pass 0) CRTC 64: trying mode 640x480@60Hz with output at 1366x768@60Hz (pass 1) Any help would be appreciated as this is very annoying. Thanks

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  • Web application interacts bi-directional with server program?

    - by Roelof Berkepeis
    I want to write a web application to play chess against the engine Crafty. I'm not new to PHP and javascript, but must learn how to interact with a server process : how can a web application and/or (jQuery) ajax interact bi-directionally with a (linux) program running on the server? At this moment i am developing on (Apache) local host. Crafty is installed on my Ubuntu PC. This well-known chess engine has no GUI, it runs in terminal by the command $ /usr/games/crafty and so you can play chess against it and even see it's calculations. I can make Crafty run by PHP, using the functions proc_open() or exec(), and most documentation i found states that the output stream should be a file .. But i think i don't want such setup, because then the webpage should be constanty polling that file (eg. by ajax) to see if some new data was appended, right? How can Crafty talk to the web page directly, saying "i have calculated another variation" or "i have decided a move" etc, then display this info on the web page and let the user give some counter move, just like in terminal. Isn't it possible to use some session / stream / listener? I have no clue at all, can anybody point me in a right direction?

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  • How do I drag my widgets without dragging other widgets?

    - by Cypher
    I have a bunch of drag-able widgets on screen. When I am dragging one of the widgets around, if I drag the mouse over another widget, that widget then gets "snagged" and is also dragged around. While this is kind of a neat thing and I can think of a few game ideas based on that alone, that was not intended. :-P Background Info I have a Widget class that is the basis for my user interface controls. It has a bunch of properties that define it's size, position, image information, etc. It also defines some events, OnMouseOver, OnMouseOut, OnMouseClick, etc. All of the event handler functions are virtual, so that child objects can override them and make use of their implementation without duplicating code. Widgets are not aware of each other. They cannot tell each other, "Hey, I'm dragging so bugger off!" Source Code Here's where the widget gets updated (every frame): public virtual void Update( MouseComponent mouse, KeyboardComponent keyboard ) { // update position if the widget is being dragged if ( this.IsDragging ) { this.Left -= (int)( mouse.LastPosition.X - mouse.Position.X ); this.Top -= (int)( mouse.LastPosition.Y - mouse.Position.Y ); } ... // define and throw other events if ( !this.WasMouseOver && this.IsMouseOver && mouse.IsButtonDown( MouseButton.Left ) ) { this.IsMouseDown = true; this.MouseDown( mouse, new EventArgs() ); } ... // define and throw other events } And here's the OnMouseDown event where the IsDraggable property gets set: public virtual void OnMouseDown( object sender, EventArgs args ) { if ( this.IsDraggable ) { this.IsDragging = true; } } Problem Looking at the source code, it's obvious why this is happening. The OnMouseDown event gets fired whenever the mouse is hovered over the Widget and when the left mouse button is "down" (but not necessarily in that order!). That means that even if I hold the mouse down somewhere else on screen, and simply move it over anything that IsDraggable, it will "hook" onto the mouse and go for a ride. So, now that it's obvious that I'm Doing It Wrong™, how do I do this correctly?

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  • Is this a ridiculous way to structure a DB schema, or am I completely missing something?

    - by Jim
    I have done a fair bit of work with relational databases, and think I understand the basic concepts of good schema design pretty well. I recently was tasked with taking over a project where the DB was designed by a highly-paid consultant. Please let me know if my gut intinct - "WTF??!?" - is warranted, or is this guy such a genius that he's operating out of my realm? DB in question is an in-house app used to enter requests from employees. Just looking at a small section of it, you have information on the users, and information on the request being made. I would design this like so: User table: UserID (primary Key, indexed, no dupes) FirstName LastName Department Request table RequestID (primary Key, indexed, no dupes) <...> various data fields containing request details UserID -- foreign key associated with User table Simple, right? Consultant designed it like this (with sample data): UsersTable UserID FirstName LastName 234 John Doe 516 Jane Doe 123 Foo Bar DepartmentsTable DepartmentID Name 1 Sales 2 HR 3 IT UserDepartmentTable UserDepartmentID UserID Department 1 234 2 2 516 2 3 123 1 RequestTable RequestID UserID <...> 1 516 blah 2 516 blah 3 234 blah The entire database is constructed like this, with every piece of data encapsulated in its own table, with numeric IDs linking everything together. Apparently the consultant had read about OLAP and wanted the 'speed of integer lookups' He also has a large number of stored procedures to cross reference all of these tables. Is this valid design for a small to mid-sized SQL DB? Thanks for comments/answers...

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  • Announcing Two Papers Addressing the RPAS Fusion Client

    - by Oracle Retail Documentation Team
    Oracle Retail has published two documents to My Oracle Support addressing the Retail Predictive Application Server (RPAS) Fusion Client, a web-based rich client developed using the latest Oracle Application Development Framework (ADF). The Fusion Client provides an enhanced user experience for communicating with the RPAS server. Oracle Retail Predictive Application Server Fusion Client Getting Started Guide Doc ID 1492759.1The Retail Predictive Application Server (RPAS) is a configurable platform that provides capabilities such as a multidimensional database structure, batch and online processing, a configurable user interface, a configurable calculation engine, user security, and utility functions such as importing and exporting, all on a highly scalable technical environment that can be deployed on a variety of hardware. This paper addresses typical questions that arise during setting up and deploying the Fusion Client, provides performance recommendations, and highlights the differences between the Classic Client and the Fusion Client. Oracle Retail RPAS Fusion Client Performance Issue Report Doc ID 1493747.1Performance issues can be frustrating for customers, and Oracle Retail will strive to assist you as you attempt to enhance the performance of your systems. To ensure the timeliest processing of your issue, retailers and partners are encouraged to respond as thoroughly as possible to each question in this document, which can be sent back for analysis by logging a Service Request and following typical Customer Support processes. The sections of the document solicit information about the following: Performance Issue Description Performance Issue Details System Configuration Data Application Configuration Data Performance Log Files

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  • How are objects modelled in a functional programming language?

    - by Giorgio
    In an answer to this question (written by Pete) there are some considerations about OOP versus FP. In particular, it is suggested that FP languages are not very suitable for modelling (persistent) objects that have an identity and a mutable state. I was wondering if this is true or, in other words, how one would model objects in a functional programming language. From my basic knowledge of Haskell I thought that one could use monads in some way, but I really do not know enough on this topic to come up with a clear answer. So, how are entities with an identity and a mutable persistent state normally modelled in a functional language? EDIT Here are some further details to clarify what I have in mind. Take a typical Java application in which I can (1) read a record from a database table into a Java object, (2) modify the object in different ways, (3) save the modified object to the database. How would this be implemented e.g. in Haskell? I would initially read the record into a record value (defined by a data definition), perform different transformations by applying functions to this initial value (each intermediate value is a new, modified copy of the original record) and then write the final record value to the database. Is this all there is to it? How can I ensure that at each moment in time only one copy of the record is valid / accessible? One does not want to have different immutable values representing different snapshots of the same object to be accessible at the same time.

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  • Javascript is not loading

    - by Oden
    Hey, I've got a problem with JavaScript under Ubuntu, that drives me crazy. I'm using Gedit for my web sites since I'm an Ubuntu user. When I start a new website I create (usually with the gnome terminal) folder structure, and I copy the files I need into them. The next step is creating an index.html where I build the design and basic JavaScript functionality. JavaScript is stored in a sub-folder of the project and when i try to load one using the tag in the header, my whole page body disappears. If the source contains a script tag with its own body, and its not the first its code wont run. I've tried to solve the problem by setting chmod to 777 with sudo chmod -R 777 . but nothing changed. CSS is loading correctly, but JS isn't. I'm using the newest version of apache, no mod_rewrite stuff, but i get the same problem when I run the html from file (file:///...) Do anyone know how to solve this problem?

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  • Strange resolution on Ubuntu 11.10

    - by FSchmidt
    I only just installed Ubuntu 11.10, so excuse me if this question is silly ;-) I have a Fujitsu Esprimo Mobile V655, nvidia 8200 graphics, and recently installed Ubuntu 11.10 using wubi. I had to modify booting commands to include nomodeset; otherwise Ubuntu would not boot. Now I did set my screen resolution to 1280 x 720, which is the correct resolution for this screen. Still, the display seems imperfect. The font sizes seem unnatural(too large / stretched) and text is quite blurry (especially in Firefox). Could it have something to do withe the nvidia graphics driver and/or the nomodeset parameter? How can I fix this? Update: I used jockey-gtk to update nvidia to the current version. This improved the resolution dramatically (no blurriness, fonts are good). It also means that I no loger need to include nomodesetin the boot commands. However, other problems were brought up by this. It seems that certain files cannot be accessed - icon (images) are missing, some task bars are completely unstyled (grey, block-form, win97 style). I also get this error message(roughly translated from German, so may be slightly different from actual) every time I reboot: Could not apply the stored configuration for the monitor: none of the chosen modi is compatible with the available modi. I have tried nvidia-xconfig, unity --reset , no improvements. Can anyone help, please?

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  • Particle trajectory smoothing: where to do the simulation?

    - by nkint
    I have a particle system in which I have particles that are moving to a target and the new targets are received via network. The list of new target are some noisy coordinates of a moving target stored in the server that I want to smooth in the client. For doing the smoothing and the particle I wrote a simple particle engine with standard euler integration model. So, my pseudo code is something like that: # pseudo code class Particle: def update(): # do euler motion model integration: # if the distance to the target is more than a limit # add a new force to the accelleration # seeking the target, # and add the accelleration to velocity # and velocity to the position positionHistory.push_back(position); if history.length > historySize : history.pop_front() class ParticleEngine: particleById = dict() # an associative array # where the keys are the id # and particle istances are sotred as values # this method is called each time a new tcp packet is received and parsed def setNetTarget(int id, Vec2D new_target): particleById[id].setNewTarget(new_target) # this method is called each new frame def draw(): for p in particleById.values: p.update() beginVertex(LINE_STRIP) for v in p.positionHistory: vertex(v.x, v.y) endVertex() The new target that are arriving are noisy but setting some accelleration/velocity parameters let the particle to have a smoothed trajectories. But if a particle trajectory is a circle after a while the particle position converge to the center (a normal behaviour of euler integration model). So I decided to change the simulation and use some other interpolation (spline?) or smooth method (kalman filter?) between the targets. Something like: switch( INTERPOLATION_MODEL ): case EULER_MOTION: ... case HERMITE_INTERPOLATION: ... case SPLINE_INTERPOLATION: ... case KALMAN_FILTER_SMOOTHING: ... Now my question: where to write the motion simulation / trajectory interpolation? In the Particle? So I will have some Particle subclass like ParticleEuler, ParticleSpline, ParticleKalman, etc..? Or in the particle engine?

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  • How to visualize code?

    - by gablin
    I've mostly only had to read my own code. As such, I've had no need to visualize the code as I already know how each and every class and module communicate with one another. But the few times I've had to read someone else's code - let us now assume we are talking about at least one larger module which contains several internal classes - I've almost always found myself wishing "This would have been so much easier to understand if I could just visualize it!" So what are the common methods or tools for enabling this? Which do you use, and why do you prefer them over the others? I've heard stuff like UML, module and class diagrams, but I imagine there are more. Furthermore, any of these is most likely better than anything I can devise on my own. EDIT: For those who answer with "Use pen and paper and just draw it": This isn't very helpful unless you explain this further. What exactly am I supposed to draw? A box for each class? Should I include the public methods? What about its fields? How should I draw connections that explain how one class uses another? What about modules? What if the language isn't object-oriented but functional or logical, or even just imperative (C, for instance)? What about global variables and functions? Is there an already-standardized way of drawing this, or do I need to think up of a method of my own? You get the drift.

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  • Emulate Historical Figures i.e. Einstein - Is this possible using linguistic logic for my http://www.ustimeline.com Education System

    - by Johnnylight
    After hearing about the success of IBM's Watson I started thinking perhaps emulating human language is now possible? My goal is to create Virtual Historical characters to represent the main characters in my Adventur-Cation The Great American Adventure program such as Einstein or Crazy Horse. The goal is to build an intelligent system capable of indexing the internet and storing the data using a schema using modern knowledge on linguistic theory (phonemes, morphemes, syntax) to build a system capable to returning a semantically sound response very similar to the response made by the same person if still alive today. The goal would be to use the same engine/system for all characters. Each characters would have their own digital representation and voice, and would organize data differently based on tags/keywords stored about the individual. Imagine a Max Headroom Einstein. Based on the success of Watson, I believe something like this may now be possible. Would be an interesting way to study history and would be a vehicle of entertainment as well. Can anyone confirm if this has already been attempted? Is anyone interested in exploring this using Cognitive Science, Psychology, Artificial Intelligence, Historical data captured on the internet, and Linguistic theory?

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  • Are there design patterns or generalised approaches for particle simulations?

    - by romeovs
    I'm working on a project (for college) in C++. The goal is to write a program that can more or less simulate a beam of particles flying trough the LHC synchrotron. Not wanting to rush into things, me and my team are thinking about how to implement this and I was wondering if there are general design patterns that are used to solve this kind of problem. The general approach we came up with so far is the following: there is a World that holds all objects you can add objects to this world such as Particle, Dipole and Quadrupole time is cut up into discrete steps, and at each point in time, for each Particle the magnetic and electric forces that each object in the World generates are calculated and summed up (luckily electro-magnetism is linear). each Particle moves accordingly (using a simple estimation approach to solve the differential movement equations) save the Particle positions repeat This seems a good approach but, for instance, it is hard to take into account symmetries that might be present (such as the magnetic field of each Quadrupole) and is this thus suboptimal. To take into account such symmetries as that of the Quadrupole field, it would be much easier to (also) make space discrete and somehow store form of the Quadrupole field somewhere. (Since 2532 or so Quadrupoles are stored this should lead to a massive gain of performance, not having to recalculate each Quadrupole field) So, are there any design patterns? Is the World-approach feasible or is it old-fashioned, bad programming? What about symmetry, how is that generally taken into acount?

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  • Minimum percentage of free physical memory that Linux require for optimal performance

    - by csoto
    Recently, we have been getting questions about this percentage of free physical memory that OS require for optimal performance, mainly applicable to physical compute nodes. Under normal conditions you may see that at the nodes without any application running the OS take (for example) between 24 and 25 GB of memory. The Linux system reports the free memory in a different way, and most of those 25gbs (of the example) are available for user processes. IE: Mem: 99191652k total, 23785732k used, 75405920k free, 173320k buffers The MOS Doc Id. 233753.1 - "Analyzing Data Provided by '/proc/meminfo'" - explains it (section 4 - "Final Remarks"): Free Memory and Used Memory Estimating the resource usage, especially the memory consumption of processes is by far more complicated than it looks like at a first glance. The philosophy is an unused resource is a wasted resource.The kernel therefore will use as much RAM as it can to cache information from your local and remote filesystems/disks. This builds up over time as reads and writes are done on the system trying to keep the data stored in RAM as relevant as possible to the processes that have been running on your system. If there is free RAM available, more caching will be performed and thus more memory 'consumed'. However this doesn't really count as resource usage, since this cached memory is available in case some other process needs it. The cache is reclaimed, not at the time of process exit (you might start up another process soon that needs the same data), but upon demand. That said, focusing more specifically on the percentage question, apart from this memory that OS takes, how much should be the minimum free memory that must be available every node so that they operate normally? The answer is: As a rule of thumb 80% memory utilization is a good threshold, anything bigger than that should be investigated and remedied.

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