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  • matlab fit exp2

    - by HelloWorld
    I'm unsuccessfully looking for documentation of fit function using exp2 (sum of 2 exponents). How to operate the function is clear: [curve, gof] = fit(x, y,'exp2'); But since there are multiple ways to fit a sum of exponents I'm trying to find out what algorithm is used. Particularly what happens when I'm fitting one exponent (the raw data) with a bit of noise, how the exponents are spread. I've simulated several cases, and it seems that it "drops" all the weight on the second set of coefficients, but row data analysis often shows different behavior. Does anyone have suggestions of documentation?

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  • Code optimization - Unused methods

    - by Yochai Timmer
    How can I tell if a method will never be used ? I know that for dll files and libraries you can't really know if someone else (another project) will ever use the code. In general I assume that anything public might be used somewhere else. But what about private methods ? Is it safe to assume that if I don't see an explicit call to that method, it won't be used ? I assume that for private methods it's easier to decide. But is it safe to decide it ONLY for private methods ?

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  • Implementing a "state-machine" logic for methods required by an object in C++

    - by user827992
    What I have: 1 hypothetical object/class + other classes and related methods that gives me functionality. What I want: linking this object to 0 to N methods in realtime on request when an event is triggered Each event is related to a single method or a class, so a single event does not necessarily mean "connect this 1 method only" but can also mean "connect all the methods from that class or a group of methods" Avoiding linked lists because I have to browse the entire list to know what methods are linked, because this does not ensure me that the linked methods are kept in a particular order (let's say an alphabetic order by their names or classes), and also because this involve a massive amount of pointers usage. Example: I have an object Employee Jon, Jon acquires knowledge and forgets things pretty easily, so his skills may vary during a period of time, I'm responsible for what Jon can add or remove from his CV, how can I implement this logic?

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  • uitableview delegate methods are not called

    - by Sean
    hi all i got the problem that the tableview methods are not called the first time the tableview is shown. if switch back to the previous view and then click the button to show the tableview again, the methods are called this time. i've to say that i show an actionsheet while the tableview is loading. the actionsheet i call in the ViewWillAppear method. thanks in advance sean

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  • code style for private methods in c#

    - by illdev
    I just found out, that it seems a common pattern to user UpperFirstLetterPascalCase() for private methods. I for myself, find this completely inconsistent with naming rules of private instance fields and variables and I find it difficult to read/debug, too. I would want to ask, why using a first upper letter for methods could be a better choice than a first lower (doThis())? Just out of curiosity...

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  • Java: when to use static methods

    - by KP65
    Hello, I am wondering when to use static methods? Say If i have a class with a few getters and setters, a method or two, and i want those methods only to be invokable on an instance object of the class. Does this mean i should use a static method? e.g Obj x = new Obj(); x.someMethod or Obj.someMethod (is this the static way?) I'm rather confused!

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  • Methods in Ruby: objects or not?

    - by Mladen Jablanovic
    Inspired by this discussion, after some googling I wasn't able to find an answer to a pretty simple question regarding methods in Ruby: are they objects or not? There are different opinions here and there, and I would really like to hear, let's say, an in-depth explanation. I'm aware of Object#method method, which takes a method name and returns a Method instance, but, on the other hand, there's a similar thing you can do with blocks to make them into Proc instances, and blocks aren't objects, so what makes methods any different?

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  • Cannot access Class methods from previous windows form - C#

    - by George
    I am writing an app, still, where I need to test some devices every minute for 30 minutes. It made sense to use a timer set to kick off every 60 secs and do whats required in the event handler. However, I need the app to wait for the 30 mins until I have finished with the timer since the following code alters the state of the devices I am trying to monitor. I obviously don't want to use any form of loop to do this. I thought of using another windows form, since I also display the progress, which will simply kick off the timer and wait until its complete. The problem I am having with this is that I use a device Class and cant seem to get access to the methods in the device class from the 2nd (3rd actually - see below) windows form. I have an initial windows form where I get input from the user, then call the 2nd windows form where it work out which tests need to be done and which device classes need to be used, and then I want to call the 3rd windows form to handle the timer. I will have up to 6-7 device classes and so wanted to only instantiate them when actually requiring them, from the 2nd form. Should I have put this logic into the 1st windows form (program class ??) ? Would I not still have the problem of not being able to access device class methods from there too ? Anyway, perhaps someone knows of a better way to do the checks every minute without the rest of the code executing (and changing the status of the devices) or how I should be accessing the methods in the app ?? Well that's the problem, I cant get that part of it to work correctly. Here is the definition for the calling form including the device class - namespace NdtStart { public partial class fclsNDTCalib : Form { NDTClass NDT = new NDTClass(); public fclsNDTCalib() (new fclsNDTTicker(NDT)).ShowDialog(); Here is the class def for the called form - namespace NdtStart { public partial class fclsNDTTicker : Form { public fclsNDTTicker() I tried lots but couldn't get the arguments to work.

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  • Is there a way to use Linq projections with extension methods

    - by Acoustic
    I'm trying to use AutoMapper and a repository pattern along with a fluent interface, and running into difficulty with the Linq projection. For what it's worth, this code works fine when simply using in-memory objects. When using a database provider, however, it breaks when constructing the query graph. I've tried both SubSonic and Linq to SQL with the same result. Thanks for your ideas. Here's an extension method used in all scenarios - It's the source of the problem since everything works fine without using extension methods public static IQueryable<MyUser> ByName(this IQueryable<MyUser> users, string firstName) { return from u in users where u.FirstName == firstName select u; } Here's the in-memory code that works fine var userlist = new List<User> {new User{FirstName = "Test", LastName = "User"}}; Mapper.CreateMap<User, MyUser>(); var result = (from u in userlist select Mapper.Map<User, MyUser>(u)) .AsQueryable() .ByName("Test"); foreach (var x in result) { Console.WriteLine(x.FirstName); } Here's the same thing using a SubSonic (or Linq to SQL or whatever) that fails. This is what I'd like to make work somehow with extension methods... Mapper.CreateMap<User, MyUser>(); var result = from u in new DataClasses1DataContext().Users select Mapper.Map<User, MyUser>(u); var final = result.ByName("Test"); foreach(var x in final) // Fails here when the query graph built. { Console.WriteLine(x.FirstName); } The goal here is to avoid having to manually map the generated "User" object to the "MyUser" domain object- in other words, I'm trying to find a way to use AutoMapper so I don't have this kind of mapping code everywhere a database read operation is needed: var result = from u in new DataClasses1DataContext().Users select new MyUser // Can this be avoided with AutoMapper AND extension methods? { FirstName = v.FirstName, LastName = v.LastName };

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  • Docs for auto-generated methods in Ruby on Rails

    - by macek
    Rails has all sorts of auto-generated methods that I've often times struggled to find documentation for. For example, in routes.rb, if I have: map.resources :projects do |p| p.resources :tasks end This will get a plethora of auto-generate path and url helpers. Where can I find documentation for how to work with these paths? I generally understand how to work with them, but more explicit docs might help me understand some of the magic that happens behind the scenes. # compare project_path(@project) project_task_path(@project, @task) # to project_path(:id => @project.id) project_task_path(:project_id => @project.id, :id => @task.id) Also, when I change an attribute on a model, @post.foo_changed? will be true. Where can I find documentation for this and all other magical methods that are created like this? If the magic is there, I'd love to take advantage of it. And finally: Is there a complete resource for config.___ statements for environment.rb? I was able to find docs for Configuration#gem but what attributes can I set within the stubs like config.active_record.___, config.action_mailer.___, config.action_controller.___, etc. Again, I'm looking for a complete resource here, not just a settings for the examples I provided. Even if you can only answer one of these questions, please chime in. These things seem to have been hiding from me and it's my goal to get them some more exposure, so I'll be upvoting all links to docs that point me to what I'm looking for. Thanks! ps, If they're not called auto-generated methods, I apologize. Someone can teach me a lesson here, too :) Edit I'm not looking for tutorials here, folks. I have a fair amount of experience with rails; I'm just looking for complete docs. E.g., I understand how routing works, I just want docs where I can read about all of the usage options.

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  • Visitor and templated virtual methods

    - by Thomas Matthews
    In a typical implementation of the Visitor pattern, the class must account for all variations (descendants) of the base class. There are many instances where the same method content in the visitor is applied to the different methods. A templated virtual method would be ideal in this case, but for now, this is not allowed. So, can templated methods be used to resolve virtual methods of the parent class? Given (the foundation): struct Visitor_Base; // Forward declaration. struct Base { virtual accept_visitor(Visitor_Base& visitor) = 0; }; // More forward declarations struct Base_Int; struct Base_Long; struct Base_Short; struct Base_UInt; struct Base_ULong; struct Base_UShort; struct Visitor_Base { virtual void operator()(Base_Int& b) = 0; virtual void operator()(Base_Long& b) = 0; virtual void operator()(Base_Short& b) = 0; virtual void operator()(Base_UInt& b) = 0; virtual void operator()(Base_ULong& b) = 0; virtual void operator()(Base_UShort& b) = 0; }; struct Base_Int : public Base { void accept_visitor(Visitor_Base& visitor) { visitor(*this); } }; struct Base_Long : public Base { void accept_visitor(Visitor_Base& visitor) { visitor(*this); } }; struct Base_Short : public Base { void accept_visitor(Visitor_Base& visitor) { visitor(*this); } }; struct Base_UInt : public Base { void accept_visitor(Visitor_Base& visitor) { visitor(*this); } }; struct Base_ULong : public Base { void accept_visitor(Visitor_Base& visitor) { visitor(*this); } }; struct Base_UShort : public Base { void accept_visitor(Visitor_Base& visitor) { visitor(*this); } }; Now that the foundation is laid, here is where the kicker comes in (templated methods): struct Visitor_Cout : public Visitor { template <class Receiver> void operator() (Receiver& r) { std::cout << "Visitor_Cout method not implemented.\n"; } }; Intentionally, Visitor_Cout does not contain the keyword virtual in the method declaration. All the other attributes of the method signatures match the parent declaration (or perhaps specification). In the big picture, this design allows developers to implement common visitation functionality that differs only by the type of the target object (the object receiving the visit). The implementation above is my suggestion for alerts when the derived visitor implementation hasn't implement an optional method. Is this legal by the C++ specification? (I don't trust when some says that it works with compiler XXX. This is a question against the general language.)

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  • Overriding LINQ extension methods

    - by Ruben Vermeersch
    Is there a way to override extension methods (provide a better implementation), without explicitly having to cast to them? I'm implementing a data type that is able to handle certain operations more efficiently than the default extension methods, but I'd like to keep the generality of IEnumerable. That way any IEnumerable can be passed, but when my class is passed in, it should be more efficient. As a toy example, consider the following: // Compile: dmcs -out:test.exe test.cs using System; namespace Test { public interface IBoat { void Float (); } public class NiceBoat : IBoat { public void Float () { Console.WriteLine ("NiceBoat floating!"); } } public class NicerBoat : IBoat { public void Float () { Console.WriteLine ("NicerBoat floating!"); } public void BlowHorn () { Console.WriteLine ("NicerBoat: TOOOOOT!"); } } public static class BoatExtensions { public static void BlowHorn (this IBoat boat) { Console.WriteLine ("Patched on horn for {0}: TWEET", boat.GetType().Name); } } public class TestApp { static void Main (string [] args) { IBoat niceboat = new NiceBoat (); IBoat nicerboat = new NicerBoat (); Console.WriteLine ("## Both should float:"); niceboat.Float (); nicerboat.Float (); // Output: // NiceBoat floating! // NicerBoat floating! Console.WriteLine (); Console.WriteLine ("## One has an awesome horn:"); niceboat.BlowHorn (); nicerboat.BlowHorn (); // Output: // Patched on horn for NiceBoat: TWEET // Patched on horn for NicerBoat: TWEET Console.WriteLine (); Console.WriteLine ("## That didn't work, but it does when we cast:"); (niceboat as NiceBoat).BlowHorn (); (nicerboat as NicerBoat).BlowHorn (); // Output: // Patched on horn for NiceBoat: TWEET // NicerBoat: TOOOOOT! Console.WriteLine (); Console.WriteLine ("## Problem is: I don't always know the type of the objects."); Console.WriteLine ("## How can I make it use the class objects when the are"); Console.WriteLine ("## implemented and extension methods when they are not,"); Console.WriteLine ("## without having to explicitely cast?"); } } } Is there a way to get the behavior from the second case, without explict casting? Can this problem be avoided?

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  • Ruby Methods: how to return an usage string when insufficient arguments are given

    - by Shyam
    Hi, After I have created a serious bunch of classes (with initialize methods), I am loading these into IRb to test each of them. I do so by creating simple instances and calling their methods to learn their behavior. However sometimes I don't remember exactly what order I was supposed to give the arguments when I call the .new method on the class. It requires me to look back at the code. However, I think it should be easy enough to return a usage message, instead of seeing: ArgumentError: wrong number of arguments (0 for 9) So I prefer to return a string with the human readable arguments, by example using "puts" or just a return of a string. Now I have seen the rescue keyword inside begin-end code, but I wonder how I could catch the ArgumentError when the initialize method is called. Thank you for your answers, feedback and comments!

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  • PHP: OOP and methods

    - by Pirkka
    Hello I`ve been wondering how to implement methods in a class. Could someone explain me what means if one does OOP in procedural style? Here is an example: class Fld extends Model { private $file; private $properties = array(); public function init($file) { $this->file = $file; $this->parseFile(); } private function parseFile() { // parses the file foreach($this->file as $line)...... .................. $this->properties = $result; } } I mean is it a good thing to have methods like these that do operations for the class properties like that. Or should I pass the class property as method parameter... I mean this would cause error if the file property wouldnt be declared.

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  • Operator Overloading with C# Extension Methods

    - by Blinky
    I'm attempting to use extension methods to add an operater overload to the C# StringBuilder class. Specifically, given StringBuilder sb, I'd like sb += "text" to become equivalent to sb.Append("text"); Here's the syntax for creating an extension method for StringBuilder: public static class sbExtensions { public static StringBuilder blah(this StringBuilder sb) { return sb; } } It successfully adds the "blah" extension method to the StringBuilder. Unfortunately, operator overloading does not seem to work: public static class sbExtensions { public static StringBuilder operator +(this StringBuilder sb, string s) { return sb.Append(s); } } Among other issues, the keyword 'this' is not allowed in this context. Are adding operator overloads via extension methods possible? If so, what's the proper way to go about it?

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  • Automatic conversion between methods and functions in Scala

    - by fikovnik
    I would like to understand the rules when can Scala automatically convert methods into functions. For example, if I have following two methods: def d1(a: Int, b: Int) {} def r[A, B](delegate: (A, B) ? Unit) {} I can do this: r(d1) But, when overloading r it will no longer work: def r[A, B, C](delegate: (A, B, C) ? Unit) {} r(d1) // no longer compiles and I have to explicitly convert method into partially applied function: r(d1 _) Is there any way to accomplish following with the explicit conversion? def r[A, B](delegate: (A, B) ? Unit) {} def r[A, B, C](delegate: (A, B, C) ? Unit) {} def d1(a: Int, b: Int) {} def d2(a: Int, b: Int, c: Int) {} r(d1) // only compiles with r(d1 _) r(d2) // only compiles with r(d2 _) There is somewhat similar question, but it is not fully explained.

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

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

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  • The Numerical ‘Magic’ of Cyclic Numbers

    - by Akemi Iwaya
    If you love crunching numbers or are just a fan of awesome number ‘tricks’ to impress your friends with, then you will definitely want to have a look at cyclic numbers. Dr Tony Padilla from the University of Nottingham shows how these awesome numbers work in Numberphile’s latest video. Cyclic Numbers – Numberphile [YouTube] Want to learn more about cyclic numbers? Then make sure to visit the Wikipedia page linked below! Cyclic number [Wikipedia]     

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  • How to apply numerical integration on a graph layout

    - by Cumatru
    I've done some basic 1 D integration, but i can't wrap my head around things and apply it to my graph layout. So, consider the picture below: if i drag the red node to the right, i'm forcing his position to my mouse position the other nodes will "follow" him, but how ? For Verlet, to compute the newPosition, i need the acceleration for every node and the currentPosition. That is what i don't understand. How to i compute the acceleration and the currentPosition ? The currentPosition will be the position of the RedNode ? If yes, doesn't that means that they will all overlap ? http://i.stack.imgur.com/NCKmO.jpg

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  • Accepting a numerical range in a function call

    - by dekpos
    I have encountered two ways of doing it: void foo(int from, int to); /* 'from' inclusive, 'to' exclusive */ void foo(int startIndex, int rangelength); Has one style historically been preferred over the other? If so, was it just a matter of convention or was it due to some deeper underlying reason? I'm currently programming in Java and noticed that the Arrays class uses the former style. The exclusivity of the to argument felt somewhat unintuitive to me, which led me to ask this question.

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  • Magic Methods in Python

    - by dArignac
    Howdy, I'm kind of new to Python and I wonder if there is a way to create something like the magic methods in PHP (http://www.php.net/manual/en/language.oop5.overloading.php#language.oop5.overloading.methods) My aim is to ease the access of child classes in my model. I basically have a parent class that has n child classes. These classes have three values, a language key, a translation key and a translation value. The are describing a kind of generic translation handling. The parent class can have translations for different translation key each in different languages. E.g. the key "title" can be translated into german and english and the key "description" too (and so far and so on) I don't want to get the child classes and filter by the set values (at least I want but not explicitly, the concrete implementation behind the magic method would do this). I want to call parent_class.title['de'] # or also possible maybe parent_class.title('de') for getting the translation of title in german (de). So there has to be a magic method that takes the name of the called method and their params (as in PHP). As far as I dug into Python this is only possible with simple attributes (_getattr_, _setattr_) or with setting/getting directly within the class (_getitem_, _setitem_) which both do not fit my needs. Maybe there is a solution for this? Please help! Thanks in advance!

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  • Threading.Timer invokes asynchronously many methods

    - by Dimitar
    Hi guys! Please help! I call a threading.timer from global.asax which invokes many methods each of which gets data from different services and writes it to files. My question is how do i make the methods to be invoked on a regular basis let's say 5 mins? What i do is: in Global.asax I declare a timer protected void Application_Start() { TimerCallback timerDelegate = new TimerCallback(myMainMethod); Timer mytimer = new Timer(timerDelegate, null, 0, 300000); Application.Add("timer", mytimer); } the declaration of myMainMethod looks like this: public static void myMainMethod(object obj) { MyDelegateType d1 = new MyDelegateType(getandwriteServiceData1); d1.BeginInvoke(null, null); MyDelegateType d2 = new MyDelegateType(getandwriteServiceData2); d2.BeginInvoke(null, null); } this approach works fine but it invokes myMainMethod every 5 mins. What I need is the method to be invoked 5 mins after all the data is retreaved and written to files on the server. How do I do that?

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