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  • Best open source Mixed Integer Optimization Solver

    - by Mark
    I am using CPLEX for solving huge optimization models (more than 100k variables) now I'd like to see if I can find an open source alternative, I solve mixed integer problems (MILP) and CPLEX works great but it is very expensive if we want to scale so I really need to find an alternative or start writing our own ad-hoc optimization library (which will be painful) Any suggestion/insight would be much appreciated

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  • There's a black hole in my server (TcpClient, TcpListener)

    - by Matías
    Hi, I'm trying to build a server that will receive files sent by clients over a network. If the client decides to send one file at a time, there's no problem, I get the file as I expected, but if it tries to send more than one I only get the first one. Here's the server code: I'm using one Thread per connected client public void ProcessClients() { while (IsListening) { ClientHandler clientHandler = new ClientHandler(listener.AcceptTcpClient()); Thread thread = new Thread(new ThreadStart(clientHandler.Process)); thread.Start(); } } The following code is part of ClientHandler class public void Process() { while (client.Connected) { using (MemoryStream memStream = new MemoryStream()) { int read; while ((read = client.GetStream().Read(buffer, 0, buffer.Length)) > 0) { memStream.Write(buffer, 0, read); } if (memStream.Length > 0) { Packet receivedPacket = (Packet)Tools.Deserialize(memStream.ToArray()); File.WriteAllBytes(Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.DesktopDirectory), Guid.NewGuid() + receivedPacket.Filename), receivedPacket.Content); } } } } On the first iteration I get the first file sent, but after it I don't get anything. I've tried using a Thread.Sleep(1000) at the end of every iteration without any luck. On the other side I have this code (for clients) . . client.Connect(); foreach (var oneFilename in fileList) client.Upload(oneFilename); client.Disconnect(); . . The method Upload: public void Upload(string filename) { FileInfo fileInfo = new FileInfo(filename); Packet packet = new Packet() { Filename = fileInfo.Name, Content = File.ReadAllBytes(filename) }; byte[] serializedPacket = Tools.Serialize(packet); netStream.Write(serializedPacket, 0, serializedPacket.Length); netStream.Flush(); } netStream (NetworkStream) is opened on Connect method, and closed on Disconnect. Where's the black hole? Can I send multiple objects as I'm trying to do? Thanks for your time.

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  • What is the sequence followed by the Linux kernel to configure a device?

    - by Jaime Soriano
    As I understood after reading the chapter related to The Linux Device Model in the Linux Device Drivers 3rd Edition, when a new device is configured, the kernel follows more or less this sequence: The Device is registered in the driver core (device_register(), what includes device initialization) A kobject is registered in the device model It provokes a hotplug event Bus and drivers are checked to see which one matches with the device Probe Device is binded to the driver My main doubt is, in step 1, when is device_register() called and what info should be yet in the device struct? Is it called by the bus to which the device is connected? Any example in the code? Have I misunderstood something? :)

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  • Applications created with real basic (real studio) for mac or windows

    - by sarmenhbbbb
    i have search high and low on the internet and it does not exist. i cant find a single website that shows a few applications created with realbasic. i saw a video that shows the user going to realbasic.com/community/ and it shows a load of applications created using realbasic. would anyone know where i can find this information. that link that i gave doesnt even work by them.

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  • Efficient Map Overlays in on Android Google Map...

    - by Ahsan
    Hi Friends, I want to do the following and am kind of stuck on these for a few days.... 1) I have used helloItemizedOverlay to add about 150 markers and it gets very very slow.....any idea what to do ? I was thinking about threads....(handler) ... 2) I was trying to draw poly lines ( I have encoded polylines, but have managed to decoded those) that move when I move the map.....(the only solution that I found was for Geopoints to be transformed into screen co-ordinates...which wont move if I move the map !) 3) I was looking for some sort of a timer function that executes a given function, say, every 1 minute or so.... 4) I was also looking for ways to clear the Google map from all the markers/lines etc.... Thanks a lot... :) - ahsan

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  • Evolutionary Algorithms: Optimal Repopulation Breakdowns

    - by Brian MacKay
    It's really all in the title, but here's a breakdown for anyone who is interested in Evolutionary Algorithms: In an EA, the basic premise is that you randomly generate a certain number of organisms (which are really just sets of parameters), run them against a problem, and then let the top performers survive. You then repopulate with a combination of crossbreeds of the survivors, mutations of the survivors, and also a certain number of new random organisms. Do that several thousand times, and efficient organisms arise. Some people also do things like introduce multiple "islands" of organisms, which are seperate populations that are allowed to crossbreed once in awhile. So, my question is: what are the optimal repopulation percentages? I have been keeping the top 10% performers, and repopulating with 30% crossbreeds and 30% mutations. The remaining 30% is for new organisms. I have also tried out the multiple island theory, and I'm interested in your results on that as well. It is not lost on me that this is exactly the type of problem an EA could solve. Are you aware of anyone trying that? Thanks in advance!

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  • The advantages and disadvantages of using ORM

    - by JHarley1
    Good Morning, I would like to discuss today the advantages and disadvantages of using ORM (such as ADO.NET). Advantages: Speeds-up Development - eliminates the need for repetitive SQL code. Reduces Development Time. Reduces Development Costs. Overcomes vendor specific SQL differences - the ORM knows how to write vendor specific SQL so you don't have to. Disadvantages: Loss in developer productivity whilst they learn to program with ORM. Developers loose understanding of what the code is actually doing - the developer is more in control using SQL. ORM has a tendency to be slow. ORM fail to compete against SQL queries for complex queries. In summary, I believe that the disadvantages of using an ORM (mainly the reduced time taken to perform repetitive tasks) is far outweighed by the disadvantages of ORM e.g. its difficulty to get to grips with. Can people point out were I am going wrong and suggest any further advantages/disadvantages. Many Thanks, J

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  • Array: mathematical sequence

    - by VaioIsBorn
    An array of integers A[i] (i 1) is defined in the following way: an element A[k] ( k 1) is the smallest number greater than A[k-1] such that the sum of its digits is equal to the sum of the digits of the number 4* A[k-1] . You need to write a program that calculates the N th number in this array based on the given first element A[1] . INPUT: In one line of standard input there are two numbers seperated with a single space: A[1] (1 <= A[1] <= 100) and N (1 <= N <= 10000). OUTPUT: The standard output should only contain a single integer A[N] , the Nth number of the defined sequence. Input: 7 4 Output: 79 Explanation: Elements of the array are as follows: 7, 19, 49, 79... and the 4th element is solution. I tried solving this by coding a separate function that for a given number A[k] calculates the sum of it's digits and finds the smallest number greater than A[k-1] as it says in the problem, but with no success. The first testing failed because of a memory limit, the second testing failed because of a time limit, and now i don't have any possible idea how to solve this. One friend suggested recursion, but i don't know how to set that. Anyone who can help me in any way please write, also suggest some ideas about using recursion/DP for solving this problem. Thanks.

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  • Data Collection (Offline - no internet) and then syncing it to generate reports from server

    - by Nishant
    So, I have a new project I am planning on taking, and needed to know what skills will be required to achieve this project. The project is to do intensive data collection in the field where they don't have internet access. As part of the data collection, images will be uploaded as part of the data collection which will have to be resized, etc. Once the data collection occurs, this data needs to be consolidated and reported on. I am thinking there are two ways of generating the report. 1. Into a PDF that can be designed. 2. Is there a way to generate an executable file (since the PDF will be huge due to multiple images, etc) and the executable file is navigation friendly with drop-downs etc. It might not be an executable file, but could be a web page or some way that this can be delivered to the client in a friendly professional way. The PDF will have to be generated somehow so that it can be printed as a hard copy. What languages and skill sets will I need to accomplish this project?

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  • Why doesn't Python require exactly four spaces per indentation level?

    - by knorv
    Whitespace is signification in Python in that code blocks are defined by their indentation. Furthermore, Guido van Rossum recommends using four spaces per indentation level (see PEP 8: Style Guide for Python Code). What was the reasoning behind not requiring exactly four spaces per indentation level as well? Are there any technical reasons? It seems like all the arguments that can be made for making whitespace define code blocks can also be used to argument for setting an exact whitespace length for one indentation level (say four spaces).

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  • Can immutable be a memory hog?

    - by ciscoheat
    Let's say we have a memory-intensive class like an Image, with chainable methods like Resize() and ConvertTo(). If this class is immutable, won't it take a huge amount of memory when I start doing things like i.Resize(500, 800).Rotate(90).ConvertTo(Gif), compared to a mutable one which modifies itself? How to handle a situation like this in a functional language?

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  • What are the Open Source alternatives to WPF/XAML?

    - by Evan Plaice
    If we've learned anything from HTML/CSS it's that, declarative languages (like XML) work best to describe User Interfaces because: It's easy to build code preprocessors that can template the code effectively. The code is in a well defined well structured (ideally) format so it's easy to parse. The technology to effectively parse or crawl an XML based source file already exists. The UIs scripted code becomes much simpler and easier to understand. It simple enough that designers are able to design the interface themselves. Programmers suck at creating UIs so it should be made easy enough for designers. I recently took a look at the meat of a WPF application (ie. the XAML) and it looks surprisingly familiar to the declarative language style used in HTML. It's apparent to me that the current state of desktop UI development is largely fractionalized, otherwise there wouldn't be so much duplicated effort in the domain of graphical user interface design (IE. GTK, XUL, Qt, Winforms, WPF, etc). There are 45 GUI platforms for Python alone It's seems reasonable to me that there should be a general purpose, open source, standardized, platform independent, markup language for designing desktop GUIs. Much like what the W3C made HTML/CSS into. WPF, or more specifically XAML seems like a pretty likely step in the right direction. Now that the 'browser wars' are over should we look forward to a future of 'desktop gui wars?' Note: This topic is relatively subjective in the attempt to be 'future-thinking.' I think that desktop GUI development in its current state sucks ((really)hard) and, even though WPF is still in it's infancy, it presents a likely solution to the problem. Update: Thanks a lot for the info, keep it comin'. Here's are the options I've gathered from the comments and answers. GladeXML Editor: Glade Interface Designer OS Platforms: All GUI Platform: GTK+ Languages: C (libglade), C++, C# (Glade#), Python, Ada, Pike, Perl, PHP, Eiffel, Ruby XRC (XML Resource) Editors: wxGlade, XRCed, wxDesigner, DialogBlocks (non-free) OS Platforms: All GUI Platform: wxWidgets Languages: C++, Python (wxPython), Perl (wxPerl), .NET (wx.NET) XML based formats that are either not free, not cross-platform, or language specific XUL Editor: Any basic text editor OS Platforms: Any OS running a browser that supports XUL GUI Platform: Gecko Engine? Languages: C++, Python, Ruby as plugin languages not base languages Note: I'm not sure if XUL deserves mentioning in this list because it's less of a desktop GUI language and more of a make-webapps-run-on-the-desktop language. Plus, it requires a browser to run. IE, it's 'DHTML for the desktop.' CookSwing Editor: Eclipse via WindowBuilder, NetBeans 5.0 (non-free) via Swing GUI Builder aka Matisse OS Platforms: All GUI Platform: Java Languages: Java only XAML (Moonlight) Editor: MonoDevelop OS Platforms: Linux and other Unix/X11 based OSes only GUI Platforms: GTK+ Languages: .NET Note: XAML is not a pure Open Source format because Microsoft controls its terms of use including the right to change the terms at any time. Moonlight can not legally be made to run on Windows or Mac. In addition, the only platform that is exempt from legal action is Novell. See this for a full description of what I mean.

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  • In what areas might the use of F# be more appropriate than C#?

    - by Peter McGrattan
    Over the last few years F# has evolved into one of Microsoft's fully supported languages employing many ideas incubated in OCaml, ML and Haskell. Over the last several years C# has extended it's general purpose features by introducing more and more functional language features: LINQ (list comprehension), Lamdas, Closures, Anonymous Delegates and more... Given C#'s adoption of these functional features and F#'s taxonomy as an impure functional language (it allows YOU to access framework libraries or change shared state when a function is called if you want to) there is a strong similarity between the two languages although each has it's own polar opposite primary emphasis. I'm interested in any successful models employing these two languages in your production polyglot programs and also the areas within production software (web apps, client apps, server apps) you have written in F# in the past year or so that you would previously have written in C#. EDIT: Edited based on feedback from close votes with the intent of reducing perceived ambiguity.

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  • Function syntax puzzler in scalaz

    - by oxbow_lakes
    Following watching Nick Partidge's presentation on deriving scalaz, I got to looking at this example, which is just awesome: import scalaz._ import Scalaz._ def even(x: Int) : Validation[NonEmptyList[String], Int] = if (x % 2 ==0) x.success else "not even: %d".format(x).wrapNel.fail println( even(3) <|*|> even(5) ) //prints: Failure(NonEmptyList(not even: 3, not even: 5)) I was trying to understand what the <|*|> method was doing, here is the source code: def <|*|>[B](b: M[B])(implicit t: Functor[M], a: Apply[M]): M[(A, B)] = <**>(b, (_: A, _: B)) OK, that is fairly confusing (!) - but it references the <**> method, which is declared thus: def <**>[B, C](b: M[B], z: (A, B) => C)(implicit t: Functor[M], a: Apply[M]): M[C] = a(t.fmap(value, z.curried), b) So I have a few questions: How come the method appears to take a monad of one type parameter (M[B]) but can get passed a Validation (which has two type paremeters)? How does the syntax (_: A, _: B) define the function (A, B) => C which the 2nd method expects? It doesn't even define an output via =>

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  • How hard is FizzBuzz? [closed]

    - by Josh K
    After reading various blog entries I took it upon myself to code a FizzBuzz program in PHP. class FizzBuzz { function __construct() { } function go() { for($i = 1; $i < 101; $i++) { if($i % 3 == 0 and $i % 5 == 0) { echo("FizzBuzz\n"); continue; } else if($i % 3 == 0) { echo("Fizz\n"); continue; } else if($i % 5 == 0) { echo("Buzz\n"); continue; } else { echo($i."\n"); } } } } $FB = new FizzBuzz(); $FB->go(); Created the FizzBuzz object just because I could, I complete this in under five minutes. Is it really that hard to do?

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  • Self Assessment Tests for Programmers

    - by THX1138.6
    I want to help the Dev team identify areas of knowledge (practical and theoretical) that they can work on. Though I am big believer in focusing on people's strengths being a good programmer requires (I think) being challenged by concepts and ideas that don't always come naturally. We work largely in the web app space using PHP & MySQL but better skills in data modelling, query optimisation, use of MVC and OOP etc. would help the team and the company a lot. I want to help the Dev team manage their careers, explore and expand their skills sets. Be all they can be and better than they were previously. I know its an idealistic goal but work must be about more than simply getting the work done. There should be some time to review, to learn, to grow and get better. Any thoughts, ideas, opinions and directions to tests or similar resources would be greatly appreciated.

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  • Setting article properties for a publication using RMO in C# .NET

    - by Pavan Kumar
    I am using transaction replication with push subscription. I am developing a UI for replication using RMO in C#.NET between different instances of the same database within same machine holding similar schema and structure. I am using Single subscriber and multiple publisher topology. During creation of publication i want to set a few article properties such as Keep the existing object unchanged ,allow schema changes at subscriber to false a,copy foriegn key constarint and copy check constraints to true. How do i set the article properties using RMO in C# .NET. I am using Visual Studio 2008 SP1.I also want to know as how we can select all the objects including Tables,Views,Stored Procedures for publishing at one stretch. I could do it for one table but i want to select all the tables at one stretch. This is the code snippet i used for selecting single table for publishing. TransArticle ta = new TransArticle(); ta.Name = "Article_1"; ta.PublicationName = "TransReplication_DB2"; ta.DatabaseName = "DB2"; ta.SourceObjectName = "person"; ta.SourceObjectOwner = "dbo"; ta.ConnectionContext = conn; ta.Create();

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  • FireLog: proper installation...

    - by kent
    I have installed the firewiresdk26 on my dev mac... and in the Tools/ directory is FireLog. I have run the FireLog 2.0.0.pkg installer on my dev mac, but the payload it deploys is installed in my /System/Library tree, as opposed to my /Developer/SDKs tree. so when I try to include the header iokit/firewire/FireLog.h it does not get found. am I missing something? or doing something wrong? or is this an error in the installer (either FW26 or FireLog installers?) I realize that the FireLog installer is intended to be run on the machine to be debugged remotely and thus it makes sense that the framework is placed in the /System/Library path, however none of the installers gets it into my developer path... I guess I just have to move it over there by hand, but before I do that I wanted to see if I'm just overlooking something silly and need to read the docs with more concentration or something... anyone run into this before? [thx]

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