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• MATLAB: Best fitness vs mean fitness, initial range

  - by Sa Ta

  Based on the example of Rastrigin's function. At the plot function, if I chose 'best fitness', on the same graph 'mean fitness' will also be plotted. I understand well about 'best fitness' whereby it plots the best function value in each generation versus iteration number. It will reach value zero after some times. I don't understand about 'mean fitness'in the graph plotted. What do those 'mean fitness' values mean? How does the 'mean fitness' graph help to understand Rastrigin's function? What are the meaning of the term initial population, initial score and initial range? I wish to have a better understanding of these terms. The default value for initial range is [0,1]. Does it mean that 0 is the lower bound (lb) and 1 is the upper bound (ub)? Do these values interfere with the lb and ub values I set in the constraints? I try to better understand about lb and ub. If my lb is 0 and ub is 5, does it mean that my final point values will be within 0 and 5? If I know the lb and ub for my problem is between 0 and 5, do I just set the initial range as [0,5] at all times and may I assume that this is the best option for initial range, and I need not try it with any other values?

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• Why does this static field always get initialized over-eagerly?

  - by TheSilverBullet

  I am looking at this excellent article from Jon Skeet. While executing the demo code, Jon Skeet says that we can expect three different kinds of behaviours. To quote that article: The runtime could decide to run the type initializer on loading the assembly to start with... Or perhaps it will run it when the static method is first run... Or even wait until the field is first accessed... When I try this out (on framework 4), I always get the first result. That is, the static method is initialized before the assembly is loaded. I have tried running this multiple times and get the same result. (I tried both the debug and release versions) Why is this so? Am I missing something?

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• Liskov substitution and abstract classes / strategy pattern

  - by Kolyunya

  I'm trying to follow LSP in practical programming. And I wonder if different constructors of subclasses violate it. It would be great to hear an explanation instead of just yes/no. Thanks much! P.S. If the answer is no, how do I make different strategies with different input without violating LSP? class IStrategy { public: virtual void use() = 0; }; class FooStrategy : public IStrategy { public: FooStrategy(A a, B b) { c = /* some operations with a, b */ } virtual void use() { std::cout << c; } private: C c; }; class BarStrategy : public IStrategy { public: BarStrategy(D d, E e) { f = /* some operations with d, e */ } virtual void use() { std::cout << f; } private: F f; };

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• Ways to organize interface and implementation in C++

  - by Felix Dombek

  I've seen that there are several different paradigms in C++ concerning what goes into the header file and what to the cpp file. AFAIK, most people, especially those from a C background, do: foo.h class foo { private: int mem; int bar(); public: foo(); foo(const foo&); foo& operator=(foo); ~foo(); } foo.cpp #include foo.h foo::bar() { return mem; } foo::foo() { mem = 42; } foo::foo(const foo& f) { mem = f.mem; } foo::operator=(foo f) { mem = f.mem; } foo::~foo() {} int main(int argc, char *argv[]) { foo f; } However, my lecturers usually teach C++ to beginners like this: foo.h class foo { private: int mem; int bar() { return mem; } public: foo() { mem = 42; } foo(const foo& f) { mem = f.mem; } foo& operator=(foo f) { mem = f.mem; } ~foo() {} } foo.cpp #include foo.h int main(int argc, char* argv[]) { foo f; } // other global helper functions, DLL exports, and whatnot Originally coming from Java, I have also always stuck to this second way for several reasons, such as that I only have to change something in one place if the interface or method names change, and that I like the different indentation of things in classes when I look at their implementation, and that I find names more readable as foo compared to foo::foo. I want to collect pro's and con's for either way. Maybe there are even still other ways? One disadvantage of my way is of course the need for occasional forward declarations.

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• How do I learn to develop financial software?

  - by Jack Smartie

  I would like to know what I have to learn to become a financial software developer in the area of brokerage/investment software. I apologize if this question is off topic. I'm not sure where to put it. What programming language(s) is most commonly used in the financial world? Financial software requires highly accurate and redundant features. Are these programming skills learned through experience, a class, or a book?

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• How do I initialize a Scala map with more than 4 initial elements in Java?

  - by GlenPeterson

  For 4 or fewer elements, something like this works (or at least compiles): import scala.collection.immutable.Map; Map<String,String> HAI_MAP = new Map4<>("Hello", "World", "Happy", "Birthday", "Merry", "XMas", "Bye", "For Now"); For a 5th element I could do this: Map<String,String> b = HAI_MAP.$plus(new Tuple2<>("Later", "Aligator")); But I want to know how to initialize an immutable map with 5 or more elements and I'm flailing in Type-hell. Partial Solution I thought I'd figure this out quickly by compiling what I wanted in Scala, then decompiling the resultant class files. Here's the scala: object JavaMapTest { def main(args: Array[String]) = { val HAI_MAP = Map(("Hello", "World"), ("Happy", "Birthday"), ("Merry", "XMas"), ("Bye", "For Now"), ("Later", "Aligator")) println("My map is: " + HAI_MAP) } } But the decompiler gave me something that has two periods in a row and thus won't compile (I don't think this is valid Java): scala.collection.immutable.Map HAI_MAP = (scala.collection.immutable.Map) scala.Predef..MODULE$.Map().apply(scala.Predef..MODULE$.wrapRefArray( scala.Predef.wrapRefArray( (Object[])new Tuple2[] { new Tuple2("Hello", "World"), new Tuple2("Happy", "Birthday"), new Tuple2("Merry", "XMas"), new Tuple2("Bye", "For Now"), new Tuple2("Later", "Aligator") })); I'm really baffled by the two periods in this: scala.Predef..MODULE$ I asked about it on #java on Freenode and they said the .. looked like a decompiler bug. It doesn't seem to want to compile, so I think they are probably right. I'm running into it when I try to browse interfaces in IntelliJ and am just generally lost. Based on my experimentation, the following is valid: Tuple2[] x = new Tuple2[] { new Tuple2<String,String>("Hello", "World"), new Tuple2<String,String>("Happy", "Birthday"), new Tuple2<String,String>("Merry", "XMas"), new Tuple2<String,String>("Bye", "For Now"), new Tuple2<String,String>("Later", "Aligator") }; scala.collection.mutable.WrappedArray<Tuple2> y = scala.Predef.wrapRefArray(x); There is even a WrappedArray.toMap() method but the types of the signature are complicated and I'm running into the double-period problem there too when I try to research the interfaces from Java.

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• Drawing Flowchart for function calculate a number in the Fibonacci Series

  - by truongvan

  I'm trying make Flowchart for function calculate a number in the Fibonacci Series. But It looks like not right. I don't how draw the recursive function. Please help me how to fix it. My flowchart: DIA This is my code: #include <iostream> using namespace std; long long Fibonacci(int input); int main() { cout << "Input Fibonacci Index number: "; int Index = 0; cin >> Index; cout << Fibonacci(i) << endl; return 0; } long long Fibonacci(int input) { if (input < 2) return input; else { return Fibonacci(input - 1) + Fibonacci(input - 2); } }

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• Where does jQuery fit-in with frameworks like JavaScriptMVC, BackboneJS, SproutCore and Knockout?

  - by Prisoner ZERO

  I have been happily using JQuery for the last 2 years and have been quite sucessful creating some really cool functionality with it...so I am very comfortable with it. I also beleive the future of the web will continue on the current client-side path. However... The next challenge seems to be coming in the form of various controller frameworks: KnockoutJS, BackboneJS, SproutCore, JavaScriptMVC (the list goes on). Additonally, there are some great AMD Loader tools for use like RequireJS or LabJS etc. However, jQuery now has define and then capabilities baked-in. It's getting harder-and-harder to keep track of it all... And now, my task seems to be to evaluate/decide-on a strategic-direction for using some form of either an MVC or MVVM framework client-side...but I have so many questions. Where does JQuery fit-in with the various controller-frameworks mentioned above? Is JQuery used alongside each or do some of them have their own 'JQuery-styled version' baked-in? Are tools like RequireJS still needed if you implement one of the various controller-frameworks mentioned above? Does the define and then capabilities baked-into JQuery now supercede the AMD Loader mentioned above? Which one seems most modular? (see notes below) NOTES: One thing I don't want in any future-framework is the requirement of having to take-in vast amounts of functionality that I don't use. Meaning, I would rather use a framework that is truly modular. For example, to use jQuery UI you have to take-in a lot other core libraries that you might not actually use. I will be experimenting with each one, but some REAL feedback would be great. I've seen some 'similar' questions, but none have really answered the above skew. Thanks in advance!

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• Why would one overload the && and & operator?

  - by acidzombie24

  The same question goes for | and ||. Why would one overload or 'use' the & and && operator? The only use i thought of are Bitwise Ands for int base types (but not float/decimals) using & logical short circuit for bools/functions that return bool. Using the && operator usually. I cant think of any classes that use those operators. Absolutely none. I know a class might support + (and not '-') which combine two strings together. I seen an object such as datetime overload '-' so two dates can be subtracted to make a timespan (obviously you cant add two dates) but i never seen &, &&, | and || used. Does anyone know of a use? In any language?

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• SQL query. An unusual join. DB implemented in sqlite-3

  - by user02814

  This is essentially a question about constructing an SQL query. The db is implemented with sqlite3. I am a relatively new user of SQL. I have two tables and want to join them in an unusual way. The following is an example to explain the problem. Table 1 (t1): id year name ------------------------- 297 2010 Charles 298 2011 David 300 2010 Peter 301 2011 Richard Table 2 (t2) id year food --------------------------- 296 2009 Bananas 296 2011 Bananas 297 2009 Melon 297 2010 Coffee 297 2012 Cheese 298 2007 Sugar 298 2008 Cereal 298 2012 Chocolate 299 2000 Peas 300 2007 Barley 300 2011 Beans 300 2012 Chickpeas 301 2010 Watermelon I want to join the tables on id and year. The catch is that (1) id must match exactly, but if there is no exact match in Table 2 for the year in Table 1, then I want to choose the year that is the next (lower) available. A selection of the kind that I want to produce would give the following result id year matchyr name food ------------------------------------------------- 297 2010 2010 Charles Coffee 298 2011 2008 David Cereal 300 2010 2007 Peter Barley 301 2011 2010 Richard Watermelon To summarise, id=297 had an exact match for year=2010 given in Table 1, so the corresponding line for id=297, year=2010 is chosen from Table 2. id=298, year=2011 did not have a matching year in Table 2, so the next available year (less than 2011) is chosen. As you can see, I would also like to know what that matched year (whether exactly , or inexactly) actually was. I would very much appreciate (1) an indication (yes/no answer) of whether this is possible to do in SQL alone, or whether I need to look outside SQL, and (2) a solution, if that is not too onerous.

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• Daylight saving time: Annoying and pointless [closed]

  - by polemon

  Daylight saving time is a big annoyance for me. Not just from the standpoint, that I never know when we set our clocks an hour ahead or an hour back. Setting the clock ahead or back disturbs my time organization, and is responsible for my bad mood around that day. From the standpoint of a programmer, it's no less annoying. you always have to check whether it isn't "that date" in the year, when you have to work with local time. I hear people have the same views on this that I have. also, I don't see any benefits from it. The supposedly added "extra hour" of sunlight; I don't feel that. In case you live in a region where daylight savings is observed (like in Germany, where I live), please tell me how you manage the annoyances that come with it, and (if possible) how to get rid of it, once and for all...

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• Code Smell: Inheritance Abuse

  - by dsimcha

  It's been generally accepted in the OO community that one should "favor composition over inheritance". On the other hand, inheritance does provide both polymorphism and a straightforward, terse way of delegating everything to a base class unless explicitly overridden and is therefore extremely convenient and useful. Delegation can often (though not always) be verbose and brittle. The most obvious and IMHO surest sign of inheritance abuse is violation of the Liskov Substitution Principle. What are some other signs that inheritance is The Wrong Tool for the Job even if it seems convenient?

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• In this slow Job Market, I have no choice to take a Job that uses VB.NET and is going to use C#. Advice?

  - by Xaisoft

  I really don't want to do VB.NET, but I need a Job and I need a Job Fast. The two positions I am looking at both have existing apps in VB.NET, but are looking to convert them to C# and do new development in C#, but as well all know, sometimes this doesn't happen for a while and you get stuck with the main language. My background is in C# and after looking at VB.NET, my head is hurting. Any advice as I tackle a Job like this. As I said, I preferably want stick with C#, but today, one may have no choice, so I have to just take what I get. I am looking for advice on this for those who have experienced it, are experiencing it, and those who have not.

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• iOS and Server: OAuth strategy

  - by drekka

  I'm trying to working how to handle authentication when I have iOS clients accessing a Node.js server and want to use services such as Google, Facebook etc to provide basic authentication for my application. My current idea of a typical flow is this: User taps a Facebook/Google button which triggers the OAuth(2) dialogs and authenticates the user on the device. At this point the device has the users access token. This token is saved so that the next time the user uses the app it can be retrieved. The access token is transmitted to my Node.js server which stores it, and tags it as un-verified. The server verifies the token by making a call to Facebook/google for the users email address. If this works the token is flagged as verified and the server knows it has a verified user. If Facebook/google fail to authenticate the token, the server tells iOS client to re-authenticate and present a new token. The iOS client can now access api calls on my Node.js server passing the token each time. As long as the token matches the stored and verified token, the server accepts the call. Obviously the tokens have time limits. I suspect it's possible, but highly unlikely that someone could sniff an access token and attempt to use it within it's lifespan, but other than that I'm hoping this is a reasonably secure method for verification of users on iOS clients without having to roll my own security. Any opinions and advice welcome.

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• Dark or light theme for Android apps?

  - by Philip Sheard

  My app allows the user to choose between a dark and a light theme, but which should it use as the default? It is a field sales app, a kind of glorified invoicing app for enterprise users. It is much larger than most apps in Google Play, and targets a vertical market. Originally I developed the app with a dark font, which was fairly standard at the time. That is still my personal preference, but most modern apps seem to have a light font.

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• What happened to Borland Delphi?

  - by Lucas

  I have the impression that Delphi isn't very popular anymore. But now at work I had to make some changes to an old Delphi program that we are still using. I used Borland Developer Studio 2006 and it was very pleasant and intuitive to work with, even though I had practically no previous exposure to it. Is Delphi still widely-used and I am simply not aware of it or are there other reasons for its decline?

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• Using PHP version 5.2 or 5.3 for end-user commercial products?

  - by Ash

  I'm doing research on what version of PHP to use when creating commercial scripts that will be sold to end users. Although the available stats aren't great, PHP 5.3 shows a 18.5% adoption rate. I'd like to use Symfony to create these scripts and it requires 5.3.2 which shows an even lower adoption rate (roughly 13% of that 18.5% use less than 5.3.2). Would I be risking much by jumping straight to PHP 5.3.2+ or should I ignore the stats and plough ahead?

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• Is there value in having technical authors in a software team?

  - by Desolate Planet

  During my 5 years in IT as a software developer, I've noticed that developers have a strong distaste towards doing any documentation. The act of taking screenshots and creating documentation seems to be a painful and time consuming experience. In one company I worked for, we had a technical documentation team with two technical authors and they developed all the user guides for our customers. In other companies where I've suggested hiring a technical author, I've been told they are not worth the money, but I'm a little unsure if that rings true. Is it better to have developers stop coding and take half a day to do screenshots and create the various guides or is it worth hiring someone who handles such tasks?

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• How should I evaluate new browser languages?

  - by Andrea

  In these days there are many projects whose aim is to bring new languages to the browser by compiling them to JavaScript. Among the others one can mention ClojureScript, CoffeScript, Dart, haXe, Emscripten, Amber Smalltalk. I'd like to try a few of these out, but I am not sure what I should be looking for when evaluating these languages to see if they are suitable for production. How should I evaluate a new browser language, and what are the pitfalls I should be looking for?

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• GPL'ing code of a third party?

  - by Mark

  I am facing the following dilemma at the moment. I am using code from a scientific paper in a commercial project. So basically I copied and pasted the code from the paper's pdf into my code editor and use it in my own code. The code in the paper does not have any copy restrictions or license(like the GPL) so I thought I would be ok using it in a commercial project. However, I have seen several gpl licensed open source projects that use the exact same code from the paper to the point of having the same variable names like in the paper. So what happened here is that a gpl license was put on a third parties non gpl'ed code. Are these open source projects in violation of the gpl or would I be in violation of the gpl because I use code which has been gpl'ed? My common sense tells me it is not allowed to gpl somebody elses non-gpl'ed (like in this case from the paper) code but I though I would ask anyway.

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• Why write clean, refactored code?

  - by Shamal Karunarathne

  Hi programming lovers, This is a question I've been asking myself for a long time. Thought of throwing out it to you. From my experience of working on several Java based projects, I've seen tons of codes which we call 'dirty'. The unconventional class/method/field naming, wrong way of handling of exceptions, unnecessarily heavy loops and recursion etc. But the code gives the intended results. Though I hate to see dirty code, it's time taking to clean them up and eventually comes the question of "is it worth? it's giving the desired results so what's the point of cleaning?" In team projects, should there be someone specifically to refactor and check for clean code? Or are there situations where the 'dirty' codes fail to give intended results or make the customers unhappy? Do feel free to comment and reply. And tell me if I'm missing something here. Thanks.

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• Does a mature agile team requires any management?

  - by ashy_32bit

  After a recent heated debate over Scrum, I realized my problem is that I think of management as a quite unnecessary and redundant activity in a fully agile team. I believe a mature Agile team does not require management or any non-technical decision making process whatsoever. To my (apparently erring) eyes it is more than obvious that the only one suitable and capable of managing a mature development team is their coach (who is the most technically competent colleague with proper communication skills). I can't imagine how a Scrum master can contribute to such a team. I am having great difficulty realizing and understanding the value of such things in Scrum and the manager as someone who is not a veteran developer but is well skilled in planning the production cycles when a coach exists in the team. What does that even mean? How on earth can someone with no edge-skills of development manage a highly technical team? Perhaps management here means something else? I see management as a total waste of time and a by-product of immaturity. In my understanding a mature team is fully self-managing. Apparently I'm mistaken since many great people say the contrary but I can't convince myself.

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• How do Tortoise svn handle concurrent file updation

  - by sabithpocker

  I don't know much about Tortoise SVN, but have been using it for a while :) I understand that it is capable of managing concurrent users on same file, but how does it do that? I am working on a file that another user is using concurrently and he committed couple of times before me, Now my files doesnt have the changes he made. Every time i end up in such a situation I gets a conflict and I am stuck. So is there something else I should do instead of just committing and causing conflict. Is it safe to do a update first and then commit ? Will I lose my local changes in this case? Please dont beat me up if this is somthing basic, A link to some tutorial will be useful in that case :)

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• What is the best Video Conference integrated solution for Us? [closed]

  - by Andrei B

  we are trying to integrate a simple Video Conferencing (open source) solution into our existing application which is written in C++ and it runs on Linux. I am currently looking at using Ekiga (formely known as GnomeMeeting) or Homer Conferencing (short: Homer). My plan is to "integrate" an existing Video Conferencing client into our existing software. Please give me recommendation on which 3rd party application or library to use to add video conferencing feature to our application. PS: Please don't close this question. I asked it on StackOverflow and it got closed, so where am I supposed to ask this question? If not here, then whats the point of asking lol.

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• Computer science curriculum for non-CS major?

  - by Daniel

  Hi all, I would like to have some ideas for building up my foundation CS skills. I have started programming computers 10 years ago and have made a pretty good career out of it. However, I cannot stop thinking that the path that brought me here was very particular, and if something goes wrong (e.g. I get laid off) it would be harder to find a job here in the US on the same salary level, OR in a top company. The reason I say that is that I am a self-learner; my degree is not in Computer Science so although I master C/C++/Java, I do not have the formal CS and mathematical background that many other software developers (esp. here in the US) have. When I look at job interview questions from Apple, Google, Amazon, I have the impression that I'd flunk those technical interviews at some point. Don't get me wrong, I know my algorithms and data structures, but when things dive too deeply into the CS realm I am in trouble. What can I do to close the gap? I was thinking about a MSc in CS, but will I even UNDERSTAND what's going on there if I'm not a CS undergrad? Should I go back to basics and get a BSc in CS instead? I always tend to go into self-study mode when I want to learn new stuff, but I have the impression that I will need more formal education in CS if I want to have a shot at working at those kinds of companies. Thank you!

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