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• Is it a good idea to always use Google as the first step to solving a problem? [closed]

  - by The Rubber Duck

  Possible Duplicate: Importance of learning to google efficiently for a programmer? Avoiding lengthy discussions, as a senior level student in CS, how can I get away from Googling problems I run into? I find myself using it too much; I seemingly reach for the instant answer and then blindly copy and paste code, hoping it works. Anyone can do that. I've read the related threads about being a better programmer, but mostly those recommend practicing on pet projects, which I have done, but again I feel EVERY wall encountered, from design through completion, was hurdled with Google. Do professionals instantly "research" their problem? Or do you guys step back and try and figure it out yourselves? I'm talking about both 'algorithm/design' problems as well as compiler issues.

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• How do you learn to effectively use more than one framework

  - by LongTTH

  Someday, my leader told me that don't reinvent the wheels, use framework built-in classes. (with a serious mood) when I implement some algorithm has been supported by .NET fx. And seriously, I didn't know about these support before, cause this is the first time I work with .NET). So I have this questions. For example, for building an Web-App we have some ways: C# with ASP.NET framework Java with JavaEE (and friends like Struts, Spring v.v.) framework. PHP with Zend framework. ... It just takes about 1 months to learn language (C#, Java, PHP...), BUT learning to use a framework effectively takes you at least SOME YEARS working (to know every bit of code has been built-in). So, how do you learn to use effectively 2 (or more) frameworks? Any ideas are welcome!

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• Resolving equivalence relations

  - by Luca Cerone

  I am writing a function to label the connected component in an image (I know there are several libraries outside, I just wanted to play with the algorithm). To do this I label the connected regions with different labels and create an equivalence table that contain information on the labels belonging to the same connected component. As an example if my equivalence table (vector of vector) looks something like: 1: 1,3 2: 2,3 3: 1,2,3 4: 4 It means that in the image there are 2 different regions, one made of elements that are labelled 1,2,3 and an other made of elements labelled 4. What is an easy and efficient way to resolve the equivalences and end up with something that looks like: 1: 1,2,3 2: 4 that I can use to "merge" the different connected regions belonging to the same connected component? Thanks a lot for the help!

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• Moving multiple objects on a map

  - by Dave

  I have multiple objects on my isometric game, for example, NPC's doing path finding automatically to walk around the map. Now there could be any number of them from 0 to infinity (hypthetical as no PC could handle that). My question is: is simply looping each one individually the smartest way to animate them all? Surely as the number of units increases you will notice a lag occuring on units near the end of loop still "waiting" for their next animation movement. The alternative is a swarm algorithm to move all objects together. Is that a smarter idea or do both situations apply depending on the circumstances of the game?

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• Vector normalization gives very imprecise results

  - by Kipras

  When I normalize vectors I receive very strange results. The lengths of the normalized vectors range from 1.0 to almost 1.5. The functions are all written by me, but I just can't find a mistake in my algorithm. When I normalize I just divide all components of the vector by the vector's length. public double length(){ return Math.sqrt(x*x + y*y); } public void normalize(){ if(length() > 0){ x /= length(); y /= length(); } } Is this supposed to happen? I mean I can see the length ranging from 0.9 to 1.1 at worst, but this is just overwhelming. Cheers

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• Length of array (C) [migrated]

  - by physics

  I have an array of 10 elements. This array stocks some informations but last information is ended by an symbol "END" (which is -1). for exemple: array[0] = 1; array[1] = 1; array[2] = 1; array[3] = 1; array[4] = 1; array[5] = 1; array[6] = END; So in this case the length is 7 instead of 10. Here is my algorithm: for (i = 0; (i < 10) && (array[i] != END); i++) { ; } at the end i contains the length. Is it correct or there is an other methode?

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• How to handle situation of programmer stealing credit for your project [on hold]

  - by shorecc

  There is a coworker who has stolen credit for my work. I created a system that will show live statuses of printing machines throughout the plant. There was one glitch in it so the coworker made an improvement and then re-wrote the entire system (copying 90% of my code, yet he added a new piece of hardware then took over the project). Now he asks me programming questions from time to time. I don't mind teaching coworkers how to program, but since he has stolen my ideas and credit in the past I am reluctant to teach him all I know. Today he asks me for a particularly challenging algorithm for this system. His code now looks exactly like the way I would program! How would you handle the situation? How can I decline helping him without appearing to not being a team player?

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• What is best way to create a cross fade effect?

  - by Starx

  While creating an Image Slider, cross-fade is one of most popular effects so far. Various slider on the internet use various techniques to create such effect. Major technique I have found so far are two: Some use a overlay and underlay div and fade in and out each others visibility. While others, create a div of exact size of the slider on the slider-initialization and play with its z-index property and then fade each other consequently. Disregarding them, what is a proper way or much better way to create a cross fade effect. P.S: I would love to read answer in form of algorithm.

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• algoritm and structure pseucode [closed]

  - by user72759

  Create entries, which administers the test, which is 20 questions, the responses and fixed the 5 correct answer for each question. Write this test, if the execution of the algorithm to each recipe realisations change the order of questions and answers and responses are notified by user enters the correct answer. 2. Writin' example, where the line 2 is used stack. Create a stack of 20 items that the first element is 1, and the next is calculated by the formula an=an-1+1/an-1. Found this stack items that are whole numbers.

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• How can I ensure reasonably spaced out enemies

  - by Samuraisoulification

  I have a simple javascript game and I'm initializing their positions on the y axis using random numbers. How can I ensure that they are reasonably spaced apart? My simple algorithm is: y = (Math.random()*1000%600); However I frequently get enemies almost directly on top of each other. This is a huge problem for the game, since it's a word game and the enemies have text on their center, that if overlapped makes them impossible to kill since you can't see the words. Any advice would be appreciated! I'm pretty new to making games in general so this has all been a learning experience for me!

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• Building a touch event driven UI from scratch: what algorithms or data types?

  - by user1717079

  I have a touch display. As input I can receive the coordinates and how many touch points are in use, basically I just get an X,Y couple for every touch event/activated point at a customizable rate. I need to start from this and build my own callback system to achieve something like Object.onUp().doSomething() meaning that I would like to abstract just the detection of some particular movements and not having to deal with raw data: what algorithms can be useful in this case? What statements? Is there some C++ library that I can dissect to get some useful info? Would you suggest the use of an heuristic algorithm?

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• How can I derive force vectors from velocity vectors?

  - by PixelRouter

  I'm making a 2d shooter ala Geometry Wars. I've got my own simple physics at work driving the background grid and all my entities. To move anything in the world I apply a Vector2d force to it. The 'engine' calculates the resulting acceleration and therefore the velocity. I am trying to port some code I found which implements the classic 'Boids' flocking algorithm, but the code I have works by calculating the Boids' velocities directly, so If i use it as is, it bypasses my physics engine. How I can translate the velocity vectors into force vectors that I can apply to the Boids and which will result in the proper velocities via my physics engine.

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• Is there such a concept as "pseudo implementation" in software development?

  - by MachuPichu

  I'm looking for a label to describe the practice of using human-based computation methods or other means of "faking" an algorithm for the sake of getting a product or demo off the ground quickly without spending the time to develop an technical/scalable/analytical solution? Eg: using Amazon Turk to count the number of empty tables in a restaurant. I'm also looking to learn more about this subject, but not sure what to search for. Human-based computation is only one method, I'm interested in the general idea of pseudo-implementation. Any ideas, recommended reading? Thanks

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• Found a better solution to a problem at work - should I deter from posting the code snippet online?

  - by Calmarius

  I think most of us, programmers, used Stack Overflow to solve every day problems: looked for an efficient algorithm to do something. Now imagine a situation: you have a problem to solve. Googled a bit, found a StackOverflow question but you are not really satisfied with the answers so far. So you have to do your own research: you need to do it because you want it in the company's app. Eventually after some hours you have found the better solution. You're happy, you added it to the company's code base, then you want to submit your answer with a code snippet (just several lines) to the question you've found before to help others too. But wait: the company's software is closed source, and you worked on it on the clock. So does this mean I shouldn't post the answer neither at work nor at home to that question in the rest of my life, because I solved it at work, and the company owns that piece of code?

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• Initialize array in O(1) -- how is this trick called?

  - by user946850

  There is this pattern that trades performance of array access against the need to iterate it when clearing it. You keep a generation counter with each entry, and also a global generation counter. The "clear" operation increases the generation counter. On each access, you compare local vs. global generation counters; if they differ, the array has been reset. This has come up in StackOverflow recently, but I don't remember if this trick has an official name. Does it? One use case is Dijkstra's algorithm if only a tiny subset of the nodes has to be relaxed, and if this has to be done repeatedly.

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• About my main Project

  - by user207365

  My project is to build a AI(Artificial Intelligence) system in which i am planning to have a raspberry pi or Intel i3/i5 processor. Raspberry pi is small and efficient but i don't know whether it can support 2 TB or more external hard disk. Where as in Intel i can have internal hard disk and at the same time external also and will be more faster with 2gb or 4gb RAM. Which is better Raspberry pi or Intel,is it possible to stimulate my ubuntu in Intel processor. the main reason using processor it to give the system decision making capability ,understanding and analyzing capabilities using different algorithm's .my processor should analyze the condition take proper steps in running the appropriate application

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• Blind As a Bat in Multi-Monitor Hell &ndash; Free Program Inside!

  - by ToStringTheory

  If you know me personally, then you probably know that I am going blind thanks to a rare genetic eye disease.  My eye disease has already been a huge detriment to my eyesight.  One of the big things to suffer is my ability to see small things moving fast right in front of me.  On a multi-monitor setup, this makes finding the cursor absolute hell. The Problem I’ll keep this short, as I’ve basically already told you what the problem is.  On my three monitor development computer, I am constantly losing the mouse during the day.  I had used the Microsoft accessibility mousefinder (press CTRL, and it pings around the mouse).  The problem with this is, there is only an effect around 50-100 PX around the mouse, and it is a very light gray, almost unnoticeable.. For someone like me, if I am not looking at the monitor when I click the CTRL button, I have to click it multiple times and dart my eyes back and forth in a futile attempt to catch a glimpse of the action…  I had tried other cursor finders, but none I liked… The Solution So what’s a guy to do when he doesn’t like his options?  MAKE A NEW OPTION…  What else should we as developers do, am I right?  So, I went ahead and made a mousefinder of my own, with 6 separate settings to change the effect.  I am releasing it here for anyone else that may also have problems finding their mouse at times. Some of its features include: Multiple options to change to achieve the exact effect you want. If your mouse moves while it is honing in, it will hone in on its current position. Many times, I would press the button and move my mouse at the same time, and many times, the mouse happened to be at a screen edge, so I would miss it. This program will restart its animation on a new screen if the mouse changes its screen while playing. Tested on Windows 7 x64 Stylish color changing from green to red. Deployed as a ClickOnce, so easy to remove if you don't like it. Press Right CTRL to trigger effect Application lives in notification area so that you can easily reach configuration or close it. To get it to run on startup, copy its application shortcut from its startmenu directory to the “Startup” folder in your startmenu. Conclusion I understand if you don’t download this…  You don’t know me and I don’t know you.  I can only say that I have honestly NOT added any virus’ or malware to the package. Yeah, I know it’s weird Download: ‘ToString(theory) Mousefinder.zip’ CRC32: EEBCE300 MD5: 0394DA581BE6F3371B5BA11A8B24BC91 SHA-1: 2080C4930A2E7D98B81787BB5E19BB24E118991C Finally, if you do use this application - please leave a comment, or email me and tell me what you think of it. Encounter a bug or hashes no longer match? I want to know that too! <warning type=”BadPun”>Now, stop messing around and start mousing around!</warning>

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• Most useful free .NET libraries?

  - by Binoj Antony

  I have used a lot of free .NET libraries, some from Microsoft itself! Which ones have you found the most useful? Dependency Injection/Inversion of Control Unity Framework - Microsoft StructureMap - Jeremy Miller Castle Windsor NInject Spring Framework Autofac Managed Extensibility Framework Logging Logging Application Block - Microsoft Log4Net - Apache Error Logging Modules and Handlers(ELMAH) NLog Compression SharpZipLib DotNetZip YUI Compressor (CSS and JS compression/minification) AjaxMinifier (in other downloads) (JS compression. Also includes MSBuild task) Ajax Ajax Control Toolkit - Microsoft AJAXNet Pro Data Mapper XmlDataMapper AutoMapper ORM NHibernate Castle ActiveRecord Subsonic XmlDataMapper Charting/Graphics Microsoft Chart Controls for ASP.NET 3.5 SP1 Microsoft Chart Controls for Winforms ZedGraph Charting NPlot - Charting for ASP.NET and WinForms PDF Creators/Generators PDFsharp iTextSharp Unit Testing/Mocking NUnit Rhino Mocks Moq TypeMock.Net xUnit.net mbUnit Machine.Specifications Automated Web Testing Selenium Watin URL Rewriting url rewriter UrlRewriting.Net Url Rewriter and Reverse Proxy - Managed Fusion Controls Krypton - Free winform controls Source Grid - A Grid control Devexpress - free controls Unclassified CSLA Framework - Business Objects Framework AForge.net - AI, computer vision, genetic algorithms, machine learning Enterprise Library 4.1 - Logging, Exception Management, Validation, Policy Injection File helpers library C5 Collections - Collections for .NET Quartz.NET - Enterprise Job Scheduler for .NET Platform MiscUtil - Utilities by Jon Skeet Lucene.net - Text indexing and searching Json.NET - Linq over JSON Flee - expression evaluator PostSharp - AOP IKVM - brings the extensive world of Java libraries to .NET. Title of the question taken from here. [EDIT] Please provide links to these free libraries as well. Once we have a huge list of this, it can be arranged in categories! Please do not mention .NET Applications/EXEs here.

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• How to setup matlabpool for multiple processors?

  - by JohnIdol

  I just setup a Extra Large Heavy Computation EC2 instance to throw it at my Genetic Algorithms problem, hoping to speed up things. This instance has 8 Intel Xeon processors (around 2.4Ghz each) and 7 Gigs of RAM. On my machine I have an Intel Core Duo, and matlab is able to work with my two cores just fine by runinng: matlabpool open 2 On the EC2 instance though, matlab only is capable of detecting 1 out of 8 processors, and if I try running: matlabpool open 8 I get an error saying that the ClusterSize is 1 since there's only 1 core on my CPU. True, there is only 1 core on each CPU, but I have 8 CPUs on the given EC2 instance! So the difference from my machine and the ec2 instance is that I have my 2 cores on a single processor locally, while the EC2 instance has 8 distinct processors. My question is, how do I get matlab to work with those 8 processors? I found this paper, but it seems related to setting up matlab with multiple EC2 instances (not related to multiple processors on the same instance, EC2 or not), which is not my problem. Any help appreciated!

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• Design suggestion for expression tree evaluation with time-series data

  - by Lirik

  I have a (C#) genetic program that uses financial time-series data and it's currently working but I want to re-design the architecture to be more robust. My main goals are: sequentially present the time-series data to the expression trees. allow expression trees to access previous data rows when needed. to optimize performance of the data access while evaluating the expression trees. keep a common interface so various types of data can be used. Here are the possible approaches I've thought about: I can evaluate the expression tree by passing in a data row into the root node and let each child node use the same data row. I can evaluate the expression tree by passing in the data row index and letting each node get the data row from a shared DataSet (currently I'm passing the row index and going to multiple synchronized arrays to get the data). Hybrid: an immutable data set is accessible by all of the expression trees and each expression tree is evaluated by passing in a data row. The benefit of the first approach is that the data row is being passed into the expression tree and there is no further query done on the data set (which should increase performance in a multithreaded environment). The drawback is that the expression tree does not have access to the rest of the data (in case some of the functions need to do calculations using previous data rows). The benefit of the second approach is that the expression trees can access any data up to the latest data row, but unless I specify what that row is, I'll have to iterate through the rows and figure out which one is the last one. The benefit of the hybrid is that it should generally perform better and still provide access to the earlier data. It supports two basic "views" of data: the latest row and the previous rows. Do you guys know of any design patterns or do you have any tips that can help me build this type of system? Should I use a DataSet to hold and present the data, or are there more efficient ways to present rows of data while maintaining a simple interface? FYI: All of my code is written in C#.

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• 500 Worker Threads, what kind of thread pool?

  - by Submerged

  I am wondering if this is the best way to do this. I have about 500 threads that run indefinitely, but Thread.sleep for a minute when done one cycle of processing. ExecutorService es = Executors.newFixedThreadPool(list.size()+1); for (int i = 0; i < list.size(); i++) { es.execute(coreAppVector.elementAt(i)); //coreAppVector is a vector of extends thread objects } The code that is executing is really simple and basically just this class aThread extends Thread { public void run(){ while(true){ Thread.sleep(ONE_MINUTE); //Lots of computation every minute } } } I do need a separate threads for each running task, so changing the architecture isn't an option. I tried making my threadPool size equal to Runtime.getRuntime().availableProcessors() which attempted to run all 500 threads, but only let 8 (4xhyperthreading) of them execute. The other threads wouldn't surrender and let other threads have their turn. I tried putting in a wait() and notify(), but still no luck. If anyone has a simple example or some tips, I would be grateful! Well, the design is arguably flawed. The threads implement Genetic-Programming or GP, a type of learning algorithm. Each thread analyzes advanced trends makes predictions. If the thread ever completes, the learning is lost. That said, I was hoping that sleep() would allow me to share some of the resources while one thread isn't "learning"

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• What's the best way to resolve this scope problem?

  - by Peter Stewart

  I'm writing a program in python that uses genetic techniques to optimize expressions. Constructing and evaluating the expression tree is the time consumer as it can happen billions of times per run. So I thought I'd learn enough c++ to write it and then incorporate it in python using cython or ctypes. I've done some searching on stackoverflow and learned a lot. This code compiles, but leaves the pointers dangling. I tried 'this_node = new Node(...' . It didn't seem to work. And I'm not at all sure how I'd delete all the references as there would be hundreds. I'd like to use variables that stay in scope, but maybe that's not the c++ way. What is the c++ way? class Node { public: char *cargo; int depth; Node *left; Node *right; } Node make_tree(int depth) { depth--; if(depth <= 0) { Node tthis_node("value",depth,NULL,NULL); return tthis_node; } else { Node this_node("operator" depth, &make_tree(depth), &make_tree(depth)); return this_node; } };

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• How do I optimize this postfix expression tree for speed?

  - by Peter Stewart

  Thanks to the help I received in this post: I have a nice, concise recursive function to traverse a tree in postfix order: deque <char*> d; void Node::postfix() { if (left != __nullptr) { left->postfix(); } if (right != __nullptr) { right->postfix(); } d.push_front(cargo); return; }; This is an expression tree. The branch nodes are operators randomly selected from an array, and the leaf nodes are values or the variable 'x', also randomly selected from an array. char *values[10]={"1.0","2.0","3.0","4.0","5.0","6.0","7.0","8.0","9.0","x"}; char *ops[4]={"+","-","*","/"}; As this will be called billions of times during a run of the genetic algorithm of which it is a part, I'd like to optimize it for speed. I have a number of questions on this topic which I will ask in separate postings. The first is: how can I get access to each 'cargo' as it is found. That is: instead of pushing 'cargo' onto a deque, and then processing the deque to get the value, I'd like to start processing it right away. I don't yet know about parallel processing in c++, but this would ideally be done concurrently on two different processors. In python, I'd make the function a generator and access succeeding 'cargo's using .next(). But I'm using c++ to speed up the python implementation. I'm thinking that this kind of tree has been around for a long time, and somebody has probably optimized it already. Any Ideas? Thanks

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• How to keep Java Frame from waiting?

  - by pypmannetjies

  I am writing a genetic algorithm that approximates an image with a polygon. While going through the different generations, I'd like to output the progress to a JFrame. However, it seems like the JFrame waits until the GA's while loop finishes to display something. I don't believe it's a problem like repainting, since it eventually does display everything once the while loop exits. I want to GUI to update dynamically even when the while loop is running. Here is my code: while (some conditions) { //do some other stuff gui.displayPolygon(best); gui.displayFitness(fitness); gui.setVisible(true); } public void displayPolygon(Polygon poly) { BufferedImage bpoly = ImageProcessor.createImageFromPoly(poly); ImageProcessor.displayImage(bpoly, polyPanel); this.setVisible(true); } public static void displayImage(BufferedImage bimg, JPanel panel) { panel.removeAll(); panel.setBounds(0, 0, bimg.getWidth(), bimg.getHeight()); JImagePanel innerPanel = new JImagePanel(bimg, 25, 25); panel.add(innerPanel); innerPanel.setLocation(25, 25); innerPanel.setVisible(true); panel.setVisible(true); }

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• C++ Template Iterator error

  - by gprime

  I am going over some code i wrote in 2006 as an undergrad. It's a simple genetic algorithm library written in C++ using templates. It use to work in 2006 when i coded it with visual studio, but now when i am trying to run it in xcode i get compile errors. This function is giving me errors: friend bool operator==(const TSPGenome<T> & t1, const TSPGenome<T> & t2) { // loop through each interator and check to see if the two genomes have the same values if(t1.genome_vec->size() != t2.genome_vec->size()) return false; else { // iterate through each vector<T>::iterator it_t1; vector<T>::iterator it_t2; it_t1 = t1.genome_vec->begin(); for(it_t2 = t2.genome_vec->begin(); it_t2 != t2.genome_vec->end(); ++it_t2, ++it_t1) { if(*it_t2 != *it_t1) return false; } } // everything seems good return true; } xcode complains about these two lines not having ; before it_t1 and it_t2. vector<T>::iterator it_t1; vector<T>::iterator it_t2; Is it because the vector type it T? I declared it in the class as follows: template <typename T> class TSPGenome : public Genome { Any help would be appreciated. Thanks!

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