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• Psychology researcher wants to learn new language

  - by user273347

  I'm currently considering R, matlab, or python, but I'm open to other options. Could you help me pick the best language for my needs? Here are the criteria I have in mind (not in order): Simple to learn. I don't really have a lot of free time, so I'm looking for something that isn't extremely complicated and/or difficult to pick up. I know some C, FWIW. Good for statistics/psychometrics. I do a ton of statistics and psychometrics analysis. A lot of it is basic stuff that I can do with SPSS, but I'd like to play around with the more advanced stuff too (bootstrapping, genetic programming, data mining, neural nets, modeling, etc). I'm looking for a language/environment that can help me run my simpler analyses faster and give me more options than a canned stat package like SPSS. If it can even make tables for me, then it'll be perfect. I also do a fair bit of experimental psychology. I use a canned experiment "programming" software (SuperLab) to make most of my experiments, but I want to be able to program executable programs that I can run on any computer and that can compile the data from the experiments in a spreadsheet. I know python has psychopy and pyepl and matlab has psychtoolbox, but I don't know which one is best. If R had something like this, I'd probably be sold on R already. I'm looking for something regularly used in academe and industry. Everybody else here (including myself, so far) uses canned stat and experiment programming software. One of the reasons I'm trying to learn a programming language is so that I can keep up when I move to another lab. Looking forward to your comments and suggestions. Thank you all for your kind and informative replies. I appreciate it. It's still a tough choice because of so many strong arguments for each language. Python - Thinking about it, I've forgotten so much about C already (I don't even remember what to do with an array) that it might be better for me to start from scratch with a simple program that does what it's supposed to do. It looks like it can do most of the things I'll need it to do, though not as cleanly as R and MATLAB. R - I'm really liking what I'm reading about R. The packages are perfect for my statistical work now. Given the purpose of R, I don't think it's suited to building psychological experiments though. To clarify, what I mean is making a program that presents visual and auditory stimuli to my specifications (hundreds of them in a preset and/or randomized sequence) and records the response data gathered from participants. MATLAB - It's awesome that cognitive and neuro folk are recommending MATLAB, because I'm preparing for the big leap from social and personality psychology to cognitive neuro. The problem is the Uni where I work doesn't have MATLAB licenses (and 3750 GBP for a compiler license is not an option for me haha). Octave looks like a good alternative. PsychToolbox is compatible with Octave, thankfully. SQL - Thanks for the tip. I'll explore that option, too. Python will be the least backbreaking and most useful in the short term. R is well suited to my current work. MATLAB is well suited to my prospective work. It's a tough call, but I think I am now equipped to make a more well-informed decision about where to go next. Thanks again!

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• Implementation of Nib project to Storyboard, Xcode

  - by Blake Loizides

  I have made a tabbed bar application in storyboard in xcode. I,m new to xcode. I got a Sample TableView XIB project from apple that I edited to my needs,The project has a UITableView that I Customized with Images, And with help of a certain forum member I was able to link up each image to a New View Controller. I tried to port or integrate My Nib Project Code to my StoryBoard Tabbed Bar Application.I thought I had everything right had to comment out a few things to get no errors, But the project only goes to a Blank Table View. Below are 2 links, 1 to my StoryBoard Tabbed Bar Application with the Table Code that I tried to integrate and the other My Successful Nib Project. Also is some code and pictures. If anybody has some free time and does not mind to help I would be extremely grateful for any input given. link1 - Storyboard link2 - XIB DecorsViewController_iPhone.m // // TableViewsViewController.m // TableViews // // Created by Axit Patel on 9/2/10. // Copyright Bayside High School 2010. All rights reserved. // #import "DecorsViewController_iPhone.h" #import "SelectedCellViewController.h" @implementation DecorsViewController_iPhone #pragma mark - Synthesizers @synthesize sitesArray; @synthesize imagesArray; #pragma mark - View lifecycle // Implement viewDidLoad to do additional setup after loading the view, typically from a nib. - (void)viewDidLoad { // Load up the sitesArray with a dummy array : sites NSArray *sites = [[NSArray alloc] initWithObjects:@"a", @"b", @"c", @"d", @"e", @"f", @"g", @"h", nil]; self.sitesArray = sites; //[sites release]; UIImage *PlumTree = [UIImage imageNamed:@"a.png"]; UIImage *CherryRoyale = [UIImage imageNamed:@"b.png"]; UIImage *MozambiqueWenge = [UIImage imageNamed:@"c.png"]; UIImage *RoyaleMahogany = [UIImage imageNamed:@"d.png"]; UIImage *Laricina = [UIImage imageNamed:@"e.png"]; UIImage *BurntOak = [UIImage imageNamed:@"f.png"]; UIImage *AutrianOak = [UIImage imageNamed:@"g.png"]; UIImage *SilverAcacia = [UIImage imageNamed:@"h.png"]; NSArray *images = [[NSArray alloc] initWithObjects: PlumTree, CherryRoyale, MozambiqueWenge, RoyaleMahogany, Laricina, BurntOak, AutrianOak, SilverAcacia, nil]; self.imagesArray = images; //[images release]; [super viewDidLoad]; } #pragma mark - Table View datasource methods // Required Methods // Return the number of rows in a section - (NSInteger)tableView:(UITableView *)table numberOfRowsInSection:(NSInteger)section { return [sitesArray count]; } // Returns cell to render for each row - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { static NSString *CellIdentifier = @"CellIdentifier"; UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier]; cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier]; // Configure cell NSUInteger row = [indexPath row]; // Sets the text for the cell //cell.textLabel.text = [sitesArray objectAtIndex:row]; // Sets the imageview for the cell cell.imageView.image = [imagesArray objectAtIndex:row]; // Sets the accessory for the cell cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator; // Sets the detailtext for the cell (subtitle) //cell.detailTextLabel.text = [NSString stringWithFormat:@"This is row: %i", row + 1]; return cell; } // Optional // Returns the number of section in a table view -(NSInteger) numberOfSectionsInTableView:(UITableView *)tableView { return 1; } #pragma mark - #pragma mark Table View delegate methods // Return the height for each cell -(CGFloat) tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath { return 78; } // Sets the title for header in the tableview -(NSString *) tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section { return @"Decors"; } // Sets the title for footer -(NSString *) tableView:(UITableView *)tableView titleForFooterInSection:(NSInteger)section { return @"Decors"; } // Sets the indentation for rows -(NSInteger) tableView:(UITableView *)tableView indentationLevelForRowAtIndexPath:(NSIndexPath *)indexPath { return 0; } // Method that gets called from the "Done" button (From the @selector in the line - [viewControllerToShow.navigationItem setRightBarButtonItem:[[[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemDone target:self action:@selector(dismissView)] autorelease]];) - (void)dismissView { [self dismissViewControllerAnimated:YES completion:NULL]; } // This method is run when the user taps the row in the tableview - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath { [tableView deselectRowAtIndexPath:indexPath animated:YES]; SelectedCellViewController *viewControllerToShow = [[SelectedCellViewController alloc] initWithNibName:@"SelectedCellViewController" bundle:[NSBundle mainBundle]]; [viewControllerToShow setLabelText:[NSString stringWithFormat:@"You selected cell: %d - %@", indexPath.row, [sitesArray objectAtIndex:indexPath.row]]]; [viewControllerToShow setImage:(UIImage *)[imagesArray objectAtIndex:indexPath.row]]; [viewControllerToShow setModalPresentationStyle:UIModalPresentationFormSheet]; [viewControllerToShow setModalTransitionStyle:UIModalTransitionStyleFlipHorizontal]; [viewControllerToShow.navigationItem setRightBarButtonItem:[[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemDone target:self action:@selector(dismissView)]]; UINavigationController *navController = [[UINavigationController alloc] initWithRootViewController:viewControllerToShow]; viewControllerToShow = nil; [self presentViewController:navController animated:YES completion:NULL]; navController = nil; // UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Tapped row!" // message:[NSString stringWithFormat:@"You tapped: %@", [sitesArray objectAtIndex:indexPath.row]] // delegate:nil // cancelButtonTitle:@"Yes, I did!" // otherButtonTitles:nil]; // [alert show]; // [alert release]; } #pragma mark - Memory management - (void)didReceiveMemoryWarning { NSLog(@"Memory Warning!"); [super didReceiveMemoryWarning]; } - (void)viewDidUnload { self.sitesArray = nil; self.imagesArray = nil; [super viewDidUnload]; } //- (void)dealloc { //[sitesArray release]; //[imagesArray release]; // [super dealloc]; //} //@end //- (void)viewDidUnload //{ // [super viewDidUnload]; // Release any retained subviews of the main view. //} - (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation { if ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPhone) { return (interfaceOrientation != UIInterfaceOrientationPortraitUpsideDown); } else { return YES; } } @end DecorsViewController_iPhone.h #import <UIKit/UIKit.h> @interface DecorsViewController_iPhone : UIViewController <UITableViewDelegate, UITableViewDataSource> { NSArray *sitesArray; NSArray *imagesArray; } @property (nonatomic, retain) NSArray *sitesArray; @property (nonatomic, retain) NSArray *imagesArray; @end SelectedCellViewController.m #import "SelectedCellViewController.h" @implementation SelectedCellViewController @synthesize labelText; @synthesize image; - (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil { if ((self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil])) { } return self; } - (void)didReceiveMemoryWarning { [super didReceiveMemoryWarning]; } #pragma mark - View lifecycle - (void)viewDidLoad { [super viewDidLoad]; [label setText:self.labelText]; [imageView setImage:self.image]; } - (void)viewDidUnload { self.labelText = nil; self.image = nil; // [label release]; // [imageView release]; [super viewDidUnload]; } - (BOOL)shouldAutorotateToInterfaceOrientation: (UIInterfaceOrientation)interfaceOrientation { return (interfaceOrientation == UIInterfaceOrientationPortrait); } @end SelectedCellViewController.h @interface SelectedCellViewController : UIViewController { NSString *labelText; UIImage *image; IBOutlet UILabel *label; IBOutlet UIImageView *imageView; } @property (nonatomic, copy) NSString *labelText; @property (nonatomic, retain) UIImage *image; @end

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• Need help with copy constructor for very basic implementation of singly linked lists

  - by Jesus

  Last week, we created a program that manages sets of strings, using classes and vectors. I was able to complete this 100%. This week, we have to replace the vector we used to store strings in our class with simple singly linked lists. The function basically allows users to declare sets of strings that are empty, and sets with only one element. In the main file, there is a vector whose elements are a struct that contain setName and strSet (class). HERE IS MY PROBLEM: It deals with the copy constructor of the class. When I remove/comment out the copy constructor, I can declare as many empty or single sets as I want, and output their values without a problem. But I know I will obviously need the copy constructor for when I implement the rest of the program. When I leave the copy constructor in, I can declare one set, either single or empty, and output its value. But if I declare a 2nd set, and i try to output either of the first two sets, i get a Segmentation Fault. Moreover, if i try to declare more then 2 sets, I get a Segmentation Fault. Any help would be appreciated!! Here is my code for a very basic implementation of everything: Here is the setcalc.cpp: (main file) #include <iostream> #include <cctype> #include <cstring> #include <string> #include "help.h" #include "strset2.h" using namespace std; // Declares of structure to hold all the sets defined struct setsOfStr { string nameOfSet; strSet stringSet; }; // Checks if the set name inputted is unique bool isSetNameUnique( vector<setsOfStr> strSetArr, string setName) { for(unsigned int i = 0; i < strSetArr.size(); i++) { if( strSetArr[i].nameOfSet == setName ) { return false; } } return true; } int main(int argc, char *argv[]) { char commandChoice; // Declares a vector with our declared structure as the type vector<setsOfStr> strSetVec; string setName; string singleEle; // Sets a loop that will constantly ask for a command until 'q' is typed while (1) { // declaring a set to be empty if(commandChoice == 'd') { cin >> setName; // Check that the set name inputted is unique if (isSetNameUnique(strSetVec, setName) == true) { strSet emptyStrSet; setsOfStr set1; set1.nameOfSet = setName; set1.stringSet = emptyStrSet; strSetVec.push_back(set1); } else { cerr << "ERROR: Re-declaration of set '" << setName << "'\n"; } } // declaring a set to be a singleton else if(commandChoice == 's') { cin >> setName; cin >> singleEle; // Check that the set name inputted is unique if (isSetNameUnique(strSetVec, setName) == true) { strSet singleStrSet(singleEle); setsOfStr set2; set2.nameOfSet = setName; set2.stringSet = singleStrSet; strSetVec.push_back(set2); } else { cerr << "ERROR: Re-declaration of set '" << setName << "'\n"; } } // using the output function else if(commandChoice == 'o') { cin >> setName; if(isSetNameUnique(strSetVec, setName) == false) { // loop through until the set name is matched and call output on its strSet for(unsigned int k = 0; k < strSetVec.size(); k++) { if( strSetVec[k].nameOfSet == setName ) { (strSetVec[k].stringSet).output(); } } } else { cerr << "ERROR: No such set '" << setName << "'\n"; } } // quitting else if(commandChoice == 'q') { break; } else { cerr << "ERROR: Ignoring bad command: '" << commandChoice << "'\n"; } } return 0; } Here is the strSet2.h: #ifndef _STRSET_ #define _STRSET_ #include <iostream> #include <vector> #include <string> struct node { std::string s1; node * next; }; class strSet { private: node * first; public: strSet (); // Create empty set strSet (std::string s); // Create singleton set strSet (const strSet &copy); // Copy constructor // will implement destructor later void output() const; strSet& operator = (const strSet& rtSide); // Assignment }; // End of strSet class #endif // _STRSET_ And here is the strSet2.cpp (implementation of class) #include <iostream> #include <vector> #include <string> #include "strset2.h" using namespace std; strSet::strSet() { first = NULL; } strSet::strSet(string s) { node *temp; temp = new node; temp->s1 = s; temp->next = NULL; first = temp; } strSet::strSet(const strSet& copy) { cout << "copy-cst\n"; node *n = copy.first; node *prev = NULL; while (n) { node *newNode = new node; newNode->s1 = n->s1; newNode->next = NULL; if (prev) { prev->next = newNode; } else { first = newNode; } prev = newNode; n = n->next; } } void strSet::output() const { if(first == NULL) { cout << "Empty set\n"; } else { node *temp; temp = first; while(1) { cout << temp->s1 << endl; if(temp->next == NULL) break; temp = temp->next; } } } strSet& strSet::operator = (const strSet& rtSide) { first = rtSide.first; return *this; }

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• Objective-C : Fowler–Noll–Vo (FNV) Hash implementation

  - by Dough

  Hi ! I have a HTTP connector in my iPhone project and queries must have a parameter set from the username using the Fowler–Noll–Vo (FNV) Hash. I have a Java implementation working at this time, this is the code : long fnv_prime = 0x811C9DC5; long hash = 0; for(int i = 0; i < str.length(); i++) { hash *= fnv_prime; hash ^= str.charAt(i); } Now on the iPhone side, I did this : int64_t fnv_prime = 0x811C9DC5; int64_T hash = 0; for (int i=0; i < [myString length]; i++) { hash *= fnv_prime; hash ^= [myString characterAtIndex:i]; } This script doesn't give me the same result has the Java one. In first loop, I get this : hash = 0 hash = 100 (first letter is "d") hash = 1865261300 (for hash = 100 and fnv_prime = -2128831035 like in Java) Do someone see something I'm missing ? Thanks in advance for the help !

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• Custom Event - invokation list implementation considerations

  - by M.A. Hanin

  I'm looking for some pointers on implementing Custom Events in VB.NET (Visual Studio 2008, .NET 3.5). I know that "regular" (non-custom) Events are actually Delegates, so I was thinking of using Delegates when implementing a Custom Event. On the other hand, Andrew Troelsen's "Pro VB 2008 and the .NET 3.5 Platform" book uses Collection types in all his Custom Events examples, and Microsoft's sample codes match that line of thought. So my question is: what considerations should I have when choosing one design over the other? What are the pros and cons for each design? Which of these resembles the inner-implementation of "regular" events? Below is a sample code demonstrating the two designs. Public Class SomeClass Private _SomeEventListeners As EventHandler Public Custom Event SomeEvent As EventHandler AddHandler(ByVal value As EventHandler) _SomeEventListeners = [Delegate].Combine(_SomeEventListeners, value) End AddHandler RemoveHandler(ByVal value As EventHandler) _SomeEventListeners = [Delegate].Remove(_SomeEventListeners, value) End RemoveHandler RaiseEvent(ByVal sender As Object, ByVal e As System.EventArgs) _SomeEventListeners.Invoke(sender, e) End RaiseEvent End Event Private _OtherEventListeners As New List(Of EventHandler) Public Custom Event OtherEvent As EventHandler AddHandler(ByVal value As EventHandler) _OtherEventListeners.Add(value) End AddHandler RemoveHandler(ByVal value As EventHandler) _OtherEventListeners.Remove(value) End RemoveHandler RaiseEvent(ByVal sender As Object, ByVal e As System.EventArgs) For Each handler In _OtherEventListeners handler(sender, e) Next End RaiseEvent End Event End Class

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• iPhone contacts app styled indexed table view implementation

  - by KSH

  My Requirement: I have this straight forward requirement of listing names of people in alphabetical order in a Indexed table view with index titles being the starting letter of alphabets (additionally a search icon at the top and # to display misc values which start with a number and other special characters). What I have done so far: 1. I am using core data for storage and "last_name" is modelled as a String property in the Contacts entity 2.I am using a NSFetchedResultsController to display the sorted indexed table view. Issues accomplishing my requirement: 1. First up, I couldn't get the section index titles to be the first letter of alphabets. Dave's suggestion in the following post, helped me achieve the same: http://stackoverflow.com/questions/1112521/nsfetchedresultscontroller-with-sections-created-by-first-letter-of-a-string The only issue I encountered with Dave' suggestion is that I couldn't get the misc named grouped under "#" index. What I have tried: 1. I tried adding a custom compare method to NSString (category) to check how the comparison and section is made but that custom method doesn't get called when specified in the NSSortDescriptor selector. Here is some code: `@interface NSString (SortString) -(NSComparisonResult) customCompare: (NSString*) aStirng; @end @implementation NSString (SortString) -(NSComparisonResult) customCompare:(NSString *)aString { NSLog(@"Custom compare called to compare : %@ and %@",self,aString); return [self caseInsensitiveCompare:aString]; } @end` Code to fetch data: `NSArray *sortDescriptors = [NSArray arrayWithObject:[[[NSSortDescriptor alloc] initWithKey:@"last_name" ascending:YES selector:@selector(customCompare:)] autorelease]]; [fetchRequest setSortDescriptors:sortDescriptors]; fetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:managedObjectContext sectionNameKeyPath:@"lastNameInitial" cacheName:@"MyCache"];` Can you let me know what I am missing and how the requirement can be accomplished ?

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• Effective java hashcode implementation

  - by Scobal

  I was wondering if someone could explain in detail what (int)(l ^ (l >>> 32)); does in the following hashcode implementation (generated by eclipse, but the same as Effective Java): private int i; private char c; private boolean b; private short s; private long l; private double d; private float f; @Override public int hashCode() { final int prime = 31; int result = 1; result = prime * result + i; result = prime * result + s; result = prime * result + (b ? 1231 : 1237); result = prime * result + c; long t = Double.doubleToLongBits(d); result = prime * result + (int) (t ^ (t >>> 32)); result = prime * result + Float.floatToIntBits(f); result = prime * result + (int) (l ^ (l >>> 32)); return result; } Thanks!

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• Email Collector / Implementation

  - by Tian

  I am implementing a simple RoR webpage that collect emails from visitors and store them as objects. I'm using it as a mini-project to try RoR and BDD. I can think of 3 features for Cucumber: 1. User submits a valid email address 2. User submits an existing email address 3. User submits an invalid email My question is, for scenarios 2 and 3, is it better to handle this via the controller? or as methods in a class? Perhaps something that throws errors if an instance is instantiated in sceanrio 2 or 3? Implementation is below, love to hear some code reviews in addition to answers to questions above. Thanks! MODEL: class Contact < ActiveRecord::Base attr_accessor :email end VIEW: <h1>Welcome To My Experiment</h1> <p>Find me in app/views/welcome/index.html.erb</p> <%= flash[:notice] %> <% form_for @contact, :url => {:action => "index"} do |f| %> <%= f.label :email %><br /> <%= f.text_field :email %> <%= submit_tag 'Submit' %> <% end %> CONTROLLER: class WelcomeController < ApplicationController def index @contact = Contact.new unless params[:contact].nil? @contact = Contact.create!(params[:contact]) flash[:notice] = "Thank you for your interest, please check your mailbox for confirmation" end end end

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• ASP.NET MVC 2.0 + Implementation of a IRouteHandler does not fire

  - by Peter

  Can anybody please help me with this as I have no idea why public IHttpHandler GetHttpHandler(RequestContext requestContext) is not executing. In my Global.asax.cs I have public class MvcApplication : System.Web.HttpApplication { public static void RegisterRoutes(RouteCollection routes) { routes.IgnoreRoute("{resource}.axd/{*pathInfo}"); routes.MapRoute( "Default", // Route name "{controller}/{action}/{id}", // URL with parameters new { controller = "Home", action = "Index", id = "" } // Parameter defaults ); routes.Add("ImageRoutes", new Route("Images/{filename}", new CustomRouteHandler())); } protected void Application_Start() { RegisterRoutes(RouteTable.Routes); } } //CustomRouteHandler implementation is below public class CustomRouteHandler : IRouteHandler { public IHttpHandler GetHttpHandler(RequestContext requestContext) { // IF I SET A BREAK POINT HERE IT DOES NOT HIT FOR SOME REASON. string filename = requestContext.RouteData.Values["filename"] as string; if (string.IsNullOrEmpty(filename)) { // return a 404 HttpHandler here } else { requestContext.HttpContext.Response.Clear(); requestContext.HttpContext.Response.ContentType = GetContentType(requestContext.HttpContext.Request.Url.ToString()); // find physical path to image here. string filepath = requestContext.HttpContext.Server.MapPath("~/logo.jpg"); requestContext.HttpContext.Response.WriteFile(filepath); requestContext.HttpContext.Response.End(); } return null; } } Can any body tell me what I'm missing here. Simply public IHttpHandler GetHttpHandler(RequestContext requestContext) does not fire. I havn't change anything in the web.config either. What I'm missing here? Please help.

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• C# String.Replace with a start/index (Added my (slow) implementation)

  - by Chris T

  I'd like an efficient method that would work something like this EDIT: Sorry I didn't put what I'd tried before. I updated the example now. // Method signature, Only replaces first instance or how many are specified in max public int MyReplace(ref string source,string org, string replace, int start, int max) { int ret = 0; int len = replace.Length; int olen = org.Length; for(int i = 0; i < max; i++) { // Find the next instance of the search string int x = source.IndexOf(org, ret + olen); if(x > ret) ret = x; else break; // Insert the replacement source = source.Insert(x, replace); // And remove the original source = source.Remove(x + len, olen); // removes original string } return ret; } string source = "The cat can fly but only if he is the cat in the hat"; int i = MyReplace(ref source,"cat", "giraffe", 8, 1); // Results in the string "The cat can fly but only if he is the giraffe in the hat" // i contains the index of the first letter of "giraffe" in the new string The only reason I'm asking is because my implementation I'd imagine getting slow with 1,000s of replaces.

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• class header+ implementation

  - by igor

  what am I doing wrong here? I keep on getting a compilation error when I try to run this in codelab (turings craft) Instructions: Write the implementation (.cpp file) of the GasTank class of the previous exercise. The full specification of the class is: A data member named amount of type double. A constructor that no parameters. The constructor initializes the data member amount to 0. A function named addGas that accepts a parameter of type double . The value of the amount instance variable is increased by the value of the parameter. A function named useGas that accepts a parameter of type double . The value of the amount data member is decreased by the value of the parameter. A function named getGasLevel that accepts no parameters. getGasLevel returns the value of the amount data member. class GasTank{ double amount; GasTank(); void addGas(double); void useGas(double); double getGasLevel();}; GasTank::GasTank(){ amount=0;} double GasTank::addGas(double a){ amount+=a;} double GasTank::useGas(double a){ amount+=a;} double GasTank::getGasLevel(){ return amount;}

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• Very slow guards in my monadic random implementation (haskell)

  - by danpriduha

  Hi! I was tried to write one random number generator implementation, based on number class. I also add there Monad and MonadPlus instance. What mean "MonadPlus" and why I add this instance? Because of I want to use guards like here: -- test.hs -- import RandomMonad import Control.Monad import System.Random x = Rand (randomR (1 ::Integer, 3)) ::Rand StdGen Integer y = do a <-x guard (a /=2) guard (a /=1) return a here comes RandomMonad.hs file contents: -- RandomMonad.hs -- module RandomMonad where import Control.Monad import System.Random import Data.List data RandomGen g => Rand g a = Rand (g ->(a,g)) | RandZero instance (Show g, RandomGen g) => Monad (Rand g) where return x = Rand (\g ->(x,g)) (RandZero)>>= _ = RandZero (Rand argTransformer)>>=(parametricRandom) = Rand funTransformer where funTransformer g | isZero x = funTransformer g1 | otherwise = (getRandom x g1,getGen x g1) where x = parametricRandom val (val,g1) = argTransformer g isZero RandZero = True isZero _ = False instance (Show g, RandomGen g) => MonadPlus (Rand g) where mzero = RandZero RandZero `mplus` x = x x `mplus` RandZero = x x `mplus` y = x getRandom :: RandomGen g => Rand g a ->g ->a getRandom (Rand f) g = (fst (f g)) getGen :: RandomGen g => Rand g a ->g -> g getGen (Rand f) g = snd (f g) when I run ghci interpreter, and give following command getRandom y (mkStdGen 2000000000) I can see memory overflow on my computer (1G). It's not expected, and if I delete one guard, it works very fast. Why in this case it works too slow? What I do wrong?

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• template style matrix implementation in c

  - by monkeyking

  From time to time I use the following code for generating a matrix style datastructure typedef double myType; typedef struct matrix_t{ |Compilation started at Mon Apr 5 02:24:15 myType **matrix; | size_t x; |gcc structreaderGeneral.c -std=gnu99 -lz size_t y; | }matrix; |Compilation finished at Mon Apr 5 02:24:15 | | matrix alloc_matrix(size_t x, size_t y){ | if(0) | fprintf(stderr,"\t-> Alloc matrix with dim (%lu,%lu) byteprline=%lu bytetotal:%l\| u\n",x,y,y*sizeof(myType),x*y*sizeof(myType)); | | myType **m = (myType **)malloc(x*sizeof(myType **)); | for(size_t i=0;i<x;i++) | m[i] =(myType *) malloc(y*sizeof(myType *)); | | matrix ret; | ret.x=x; | ret.y=y; | ret.matrix=m; | return ret; | } And then I would change my typedef accordingly if I needed a different kind of type for the entries in my matrix. Now I need 2 matrices with different types, an easy solution would be to copy/paste the code, but is there some way to do a template styled implementation. Thanks

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• Request-local storage in ASP.NET (accessible to the code from IHttpModule implementation)

  - by IgorK

  I need to have some object hanging around between two events I'm interested in: PreRequestHandlerExecute (where I create an instance of my object and want to save it) and PostRequestHandlerExecute (where I want to get to the object). After the second event the object is not needed for my purposes and should be discarded either by storage or my explicit action. So the ideal context where my object should be stored is per request (with guaranteed no sharing issues when different threads are serving requests... or processes/servers :) ) Take into account that actual implementation I can do is being made from a HttpModule and is supposed to be a pluggable solution for already written web apps (so the option to provide some state using static/instance variables in Global.asax doesn't look good - I will have to modify Global.asax on every web application). Cache seems to be too broad for this use. I tried to see whether httpContext.Application (of type HttpApplicationState) is good for me or not, but cannot get whether it is exactly per HttpApplication instance or not (AFAIK you can have several instances of HttpApplications used on different threads and therefore serving several requests simultaneously - then using storage shared between threads will not work correctly; otherwise I would use it because one HttpApplication instance serves exactly one request at a time). Something could be done with storing state on the HttpModule instances if I know for sure that it's exactly bound 1-to-1 with every HttpApplication instance running (but again I need a proof that HttpApplication instance is 1-to-1 with my HttpModule's instance). Any valuable and reputable links on these topics are much appreciated... Would be great to find something particularly well-suited for per request situation (because otherwise I may end up with something ulgy... probably either some 'broader' scoped storage and some hacks to have different keys in the storage for different requests, OR using a thread-local thing and in this way commit to the theory that IIS/ASP.NET will not ever serve first event from one thread and the second event from the other thread and so on)

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• Implementation of delegates in C#

  - by Ram

  Hi, I am trying to learn on how to use delegates efficiently in C# and I was just wondering if anyone can guide me through... The following is a sample implementation using delegates... All I am doing is just passing a value through a delegate from one class to another... Please tell me if this is the right way to implement... And also your suggestions... Also, please note that I have de-registered the delegate in : void FrmSample_FormClosing(object sender, FormClosingEventArgs e) { sampleObj.AssignValue -= new Sample.AssignValueDelegate(AssignValue); } Is this de-registration necessary? The following is the code that I have written.. public partial class FrmSample : Form { Sample sampleObj; public FrmSample() { InitializeComponent(); this.Load += new EventHandler(FrmSample_Load); this.FormClosing += new FormClosingEventHandler(FrmSample_FormClosing); sampleObj = new Sample(); sampleObj.AssignValue = new Sample.AssignValueDelegate(AssignValue); } void FrmSample_FormClosing(object sender, FormClosingEventArgs e) { sampleObj.AssignValue -= new Sample.AssignValueDelegate(AssignValue); } void FrmSample_Load(object sender, EventArgs e) { sampleObj.LoadValue(); } void AssignValue(string value) { MessageBox.Show(value); } } class Sample { public delegate void AssignValueDelegate(string value); public AssignValueDelegate AssignValue; internal void LoadValue() { if (AssignValue != null) { AssignValue("This is a test message"); } } } Pls provide your feedback on whether this is right... Thanks, Ram

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• How to deserialize implementation classes in OSGi

  - by Daniel Schneller

  In an eRCP OSGi based application the user can push a button and go to a lock screen similar to that of Windows or Mac OS X. When this happens, the current state of the application is serialized to a file and control is handed over to the lock screen. In this mobile application memory is very tight, so we need to get rid of the original view/controller when the lock screen comes up. This works fine and we end up with a binary serialized file. Once the user logs back in, the file is read in again and the original state of the application restored. This works fine as well, except when the controller that was serialized contained a reference to an object which comes from a different bundle. In my concrete case the original controller (from bundle A) can call a web service and gets a result back. Nothing fancy, just some Strings and Numbers in a simple value holder class. However the controller only sees this as a Result interface; the actual runtime object (ResultImpl) is defined and created in a different bundle (bundle B, the webservice client implementation) and returned via a service call. When the deserialization now tries to thaw the controller from the file, it throws a ClassNotFound exception, complaining about not being able to deserialize the result object, because deserialization is called from bundle A, which cannot see the ResultImpl class from bundle B. Any ideas on how to work around that? The only thing I could come up with is to clone all the individual values into another object, defined in the controller's bundle, but this seems like quite a hassle.

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• Understanding the workflow of the messages in a generic server implementation in Erlang

  - by Chiron

  The following code is from "Programming Erlang, 2nd Edition". It is an example of how to implement a generic server in Erlang. -module(server1). -export([start/2, rpc/2]). start(Name, Mod) -> register(Name, spawn(fun() -> loop(Name, Mod, Mod:init()) end)). rpc(Name, Request) -> Name ! {self(), Request}, receive {Name, Response} -> Response end. loop(Name, Mod, State) -> receive {From, Request} -> {Response, State1} = Mod:handle(Request, State), From ! {Name, Response}, loop(Name, Mod, State1) end. -module(name_server). -export([init/0, add/2, find/1, handle/2]). -import(server1, [rpc/2]). %% client routines add(Name, Place) -> rpc(name_server, {add, Name, Place}). find(Name) -> rpc(name_server, {find, Name}). %% callback routines init() -> dict:new(). handle({add, Name, Place}, Dict) -> {ok, dict:store(Name, Place, Dict)}; handle({find, Name}, Dict) -> {dict:find(Name, Dict), Dict}. server1:start(name_server, name_server). name_server:add(joe, "at home"). name_server:find(joe). I tried so hard to understand the workflow of the messages. Would you please help me to understand the workflow of this server implementation during the executing of the functions: server1:start, name_server:add and name_server:find?

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• How to improve multi-threaded access to Cache (custom implementation)

  - by Andy

  I have a custom Cache implementation, which allows to cache TCacheable<TKey> descendants using LRU (Least Recently Used) cache replacement algorithm. Every time an element is accessed, it is bubbled up to the top of the LRU queue using the following synchronized function: // a single instance is created to handle all TCacheable<T> elements public class Cache() { private object syncQueue = new object(); private void topQueue(TCacheable<T> el) { lock (syncQueue) if (newest != el) { if (el.elder != null) el.elder.newer = el.newer; if (el.newer != null) el.newer.elder = el.elder; if (oldest == el) oldest = el.newer; if (oldest == null) oldest = el; if (newest != null) newest.newer = el; el.newer = null; el.elder = newest; newest = el; } } } The bottleneck in this function is the lock() operator, which limits cache access to just one thread at a time. Question: Is it possible to get rid of lock(syncQueue) in this function while still preserving the queue integrity?

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• ASP.NET MVC 2.0 + Implementation of a IRouteHandler goes not fire

  - by Peter

  Can anybody please help me with this as I have no idea why public IHttpHandler GetHttpHandler(RequestContext requestContext) is not executing. In my Global.asax.cs I have public class MvcApplication : System.Web.HttpApplication { public static void RegisterRoutes(RouteCollection routes) { routes.IgnoreRoute("{resource}.axd/{*pathInfo}"); routes.MapRoute( "Default", // Route name "{controller}/{action}/{id}", // URL with parameters new { controller = "Home", action = "Index", id = "" } // Parameter defaults ); routes.Add("ImageRoutes", new Route("Images/{filename}", new CustomRouteHandler())); } protected void Application_Start() { RegisterRoutes(RouteTable.Routes); } } //CustomRouteHandler implementation is below public class CustomRouteHandler : IRouteHandler { public IHttpHandler GetHttpHandler(RequestContext requestContext) { // IF I SET A BREAK POINT HERE IT DOES NOT HIT FOR SOME REASON. string filename = requestContext.RouteData.Values["filename"] as string; if (string.IsNullOrEmpty(filename)) { // return a 404 HttpHandler here } else { requestContext.HttpContext.Response.Clear(); requestContext.HttpContext.Response.ContentType = GetContentType(requestContext.HttpContext.Request.Url.ToString()); // find physical path to image here. string filepath = requestContext.HttpContext.Server.MapPath("~/logo.jpg"); requestContext.HttpContext.Response.WriteFile(filepath); requestContext.HttpContext.Response.End(); } return null; } } Can any body tell me what I'm missing here. Simply public IHttpHandler GetHttpHandler(RequestContext requestContext) does not fire. I havn't change anything in the web.config either. What I'm missing here? Please help.

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• Dynamic WebService implementation

  - by chardex

  I have a set of different interfaces and I need to give them access via web services. I have implemented this task in .NET as follows: dynamically generated interface implementation on the IL, marked methods with WebMethod annotation, and in *.asmx handler called generated stub. More needs to be able to change the method signatures (eg change the type of certain argument or add new arguments), ie not always explicitly implement an interface, and use it as a decorator pattern. Example: interface ISomeService { void simpleMetod (String arg1); void customMetod (CusomType arg1, Integer arg2); } // Need to dynamically generate such class @WebService class SomeWebService { private ISomeService someService = new SomeServiceImpl (); @WebMethod public void simpleMethod (String arg1) { someService.simpleMethod (arg1); } @WebMethod public void customMethod (String arg1, Integer arg2) { someService.customMethod (CusomType.fromString (arg1), arg2); } } Interfaces such as ISomeService quite a lot. And manually write code like this I don't want. I work with Java recently, what technology/libraries should be used to solve such task. Thanks.

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• Translating Your Customizations

  - by Richard Bingham

  This blog post explains the basics of translating the customizations you can make to Fusion Applications products, with the inclusion of information for both composer-based customizations and the generic design-time customizations done via JDeveloper. Introduction Like most Oracle Applications, Fusion Applications installs on-premise with a US-English base language that is, in Release 7, supported by the option to add up to a total of 22 additional language packs (In Oracle Cloud production environments languages are pre-installed already). As such many organizations offer their users the option of working with their local language, and logically that should also apply for any customizations as well. Composer-based UI Customizations Customizations made in Page Composer take into consideration the session LOCALE, as set in the user preferences screen, during all customization work, and stores the customization in the MDS repository accordingly. As such the actual new or changed values used will only apply for the same language under which the customization was made, and text for any other languages requires a separate upload. See the Resource Bundles section below, which incidentally also applies to custom UI changes done in JDeveloper. You may have noticed this when you select the “Select Text Resource” menu option when editing the text on a page. Using this ensures that the resource bundles are used, whereas if you define a static value in Expression Builder it will never be available for translation. Notice in the screenshot below the “What’s New” custom value I have already defined using the ‘Select Text Resource’ feature is internally using the adfBundle groovy function to pull the custom value for my key (RT_S_1) from the ComposerOverrideBundle. Figure 1 – Page Composer showing the override bundle being used. Business Objects Customizing the Business Objects available in the Applications Composer tool for the CRM products, such as adding additional fields, also operates using the session language. Translating these additional values for these fields into other installed languages requires loading additional resource bundles, again as described below. Reports and Analytics Most customizations to Reports and BI Analytics are just essentially reorganizations and visualizations of existing number and text data from the system, and as such will use the appropriate values based on the users session language. Where a translated value or string exists for that session language, it will be used without the need for additional work. Extending through the addition of brand new reports and analytics requires another method of loading the translated strings, as part of what is known as ‘Localizing’ the BI Catalog and Metadata. This time it is via an export/import of XML data through the BI Administrators console, and is described in the OBIEE Admin Guide. Fusion Applications reports based on BI Publisher are already defined in template-per-locale, and in addition provide an extra process for getting the data for translation and reloading. This again uses the standard resource bundle format. Loading a custom report is illustrated in this video from our YouTube channel which shows the screen for both setting the template local and running an export for translation. Fusion Applications Menus Whilst the seeded Navigator and Global Menu values are fully translated when the additional language is installed, if they are customized then the change or new menu item will apply universally, not currently per language. This is set to change in a future release with the new UI Text Editor feature described below. More on Resource Bundles As mentioned above, to provide translations for most of your customizations you need to add values to a resource bundle. This is an industry open standard (OASIS) format XML file with the extension .xliff, and store translated values for the strings used by ADF at run-time. The general process is that these values are exported from the MDS repository, manually edited, and then imported back in again.This needs to be done by an administrator, via either WLST commands or through Enterprise Manager as per the screenshot below. This is detailed out in the Fusion Applications Extensibility Guide. For SaaS environments the Cloud Operations team can assist. Figure 2 – Enterprise Manager’s MDS export used getting resource bundles for manual translation and re-imported on the same screen. All customized strings are stored in an override bundle (xliff file) for each locale, suffixed with the language initials, with English ones being saved to the default. As such each language bundle can be easily identified and updated. Similarly if you used JDeveloper to create your own applications as extensions to Fusion Applications you would use the native support for resource bundles, and add them into the faces-config.xml file for inclusion in your application. An example is this ADF customization video from our YouTube channel. JDeveloper also supports automatic synchronization between your underlying resource bundles and any translatable strings you add – very handy. For more information see chapters on “Using Automatic Resource Bundle Integration in JDeveloper” and “Manually Defining Resource Bundles and Locales” in the Oracle Fusion Middleware Web User Interface Developer’s Guide for Oracle Application Development Framework. FND Messages and Look-ups FND Messages, as defined here, are not used for UI labels (they are known as ‘strings’), but are the responses back to users as a result of an action, such as from a page submit. Each ‘message’ is defined and stored in the related database table (FND_MESSAGES_B), with another (FND_MESSAGES_TL) holding any language-specific values. These come seeded with the additional language installs, however if you customize the messages via the “Manage Messages” task in Functional Setup Manager, or add new ones, then currently (in Release 7) you’ll need to repeat it for each language. Figure 3 – An FND Message defined in an English user session. Similarly Look-ups are stored in a translation table (FND_LOOKUP_VALUES_TL) where appropriate, and can be customized by setting the users session language and making the change  in the Setup and Maintenance task entitled “Manage [Standard|Common] Look-ups”. Online Help Yes, in fact all the seeded help is applied as part of each language pack install as part of the post-install provisioning process. If you are editing or adding custom online help then the Create Help screen provides a drop-down of which language your help customization will apply to. This is shown in the video below from our YouTube channel, and obviously you’ll need to it for each language in use. What is Coming for Translations? Currently planned for Release 8 is something called the User Interface (UI) Text Editor. This tool will allow the editing of all the text shown on the pages and forms of Fusion Application. This will provide a search based on a particular term or word, say “Worker”, and will allow it to be adjusted, say to “Employee”, which then updates all the Resource Bundles that contain it. In the case of multi-language environments, it will use the users session language (locale) to know which Resource Bundles to apply the change to. This capability will also support customization sandboxes, to help ensure changes can be tested and approved.  It is also interesting to note that the design currently allows any page-specific customizations done using Page Composer or Application Composer to over-write the global changes done via the UI Text Editor, allowing for special context-sensitive values to still be used. Further Reading and Resources The following short list provides the mains resources for digging into more detail on translation support for both Composer and JDeveloper customization projects. There is a dedicated chapter entitled “Translating Custom Text” in the Fusion Applications Extensibility Guide. This has good examples and steps for many tasks, especially administering resource bundles. Using localization formatting (numbers, dates etc) for design-time changes is well documented in the Fusion Applications Developer Guide. For more guidelines on general design-time globalization, see either the ‘Internationalizing and Localizing Pages’ chapter in the Oracle Fusion Middleware Web User Interface Developer’s Guide for Oracle Application Development Framework (Oracle Fusion Applications Edition) or the general Oracle Database Globalization Support Guide. The Oracle Architecture ‘A-Team’ provided a recent post on customizing the user session timeout popup, using design-time changes to resource bundles. It has detailed step-by-step examples which can be a useful illustration.

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• C++ : C++ Primer (Stanley Lipmann) or The C++ programming language (special edition)

  - by Kim

  I have a Computer Science degree (long2 time ago) .. I do know Java OOP but i am now trying to pick up C++. I do have C and of course data structure using C or pascal. I have started reading Bjarne Stroustrup book (The C++ Programming Language - Special Edition) but find it extremely difficult esp. some section which i don't have exposure such as Recursive Descent Parser (chapter 6). In terms of the language i don't foresee i have problem but i have problem as mentioned cos' those topic are usually covered in a Master Degree program such as construction of compiler. I just bought a book called C++ primer (Stanley Lipmann) which i heard it is a very good book for C++. Only setback is it's of course no match with the amount of information from the original C++ creator. Please advice. Thanks.

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• e Verification Language Complier

  - by joe

  Is there any free complier for Verisity's e Verification Language ?

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• C++ vs Matlab vs Python as a main language for Computer Vision Postgraduate

  - by Hough

  Hi all, Firstly, sorry for a somewhat long question but I think that many people are in the same situation as me and hopefully they can also gain some benefit from this. I'll be starting my PhD very soon which involve the fields of computer vision, pattern recognition and machine learning. Currently, I'm using opencv (2.1) C++ interface and I especially like its powerful Mat class and the overloaded operations available for matrix and image seamless operations and transformations. I've also tried (and implemented many small vision projects) using opencv python interface (new bindings; opencv 2.1) and I really enjoy python's ability to integrate opencv, numpy, scipy and matplotlib. But recently, I went back to opencv C++ interface because I felt that the official python new bindings were not stable enough and no overloaded operations are available for matrices and images, not to mention the lack of machine learning modules and slow speeds in certain operations. I've also used Matlab extensively in the past and although I've used mex files and other means to speed up the program, I just felt that Matlab's performance was inadequate for real-time vision tasks, be it for fast prototyping or not. When the project becomes larger and larger, many tasks have to be re-written in C and compiled into Mex files increasingly and Matlab becomes nothing more than a glue language. Here comes the sub-questions: For postgrad studies in these fields (machine learning, vision, pattern recognition), what is your main or ideal programming language for rapid prototyping of ideas and testing algorithms contained in papers? For postgrad studies, can you list down the pros and cons of using the following languages? C++ (with opencv + gsl + svmlib + other libraries) vs Matlab (with all its toolboxes) vs python (with the imcomplete opencv bindings + numpy + scipy + matplotlib). Are there computer vision PhD/postgrad students here who are using only C++ (with all its availabe libraries including opencv) without even needing to resort to Matlab or python? In other words, given the current existing computer vision or machine learning libraries, is C++ alone sufficient for fast prototyping of ideas? If you're currently using Java or C# for your postgrad work, can you list down the reasons why they should be used and how they compare to other languages in terms of available libraries? What is the de facto vision/machine learning programming language and its associated libraries used in your university research group? Thanks in advance.

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• Lawler's Algorithm Implementation Assistance

  - by Richard Knop

  Here is my implemenation of Lawler's algorithm in PHP (I know... but I'm used to it): <?php $jobs = array(1, 2, 3, 4, 5, 6); $jobsSubset = array(2, 5, 6); $n = count($jobs); $processingTimes = array(2, 3, 4, 3, 2, 1); $dueDates = array(3, 15, 9, 7, 11, 20); $optimalSchedule = array(); foreach ($jobs as $j) { $optimalSchedule[] = 0; } $dicreasedCardinality = array(); for ($i = $n; $i >= 1; $i--) { $x = 0; $max = 0; // loop through all jobs for ($j = 0; $j < $i; $j++) { // ignore if $j already is in the $dicreasedCardinality array if (false === in_array($j, $dicreasedCardinality)) { // if the job has no succesor in $jobsSubset if (false === isset($jobs[$j+1]) || false === in_array($jobs[$j+1], $jobsSubset)) { // here I find an array index of a job with the maximum due date // amongst jobs with no sucessor in $jobsSubset if ($x < $dueDates[$j]) { $x = $dueDates[$j]; $max = $j; } } } } // move the job at the end of $optimalSchedule $optimalSchedule[$i-1] = $jobs[$max]; // decrease the cardinality of $jobs $dicreasedCardinality[] = $max; } print_r($optimalSchedule); Now the above returns an optimal schedule like this: Array ( [0] => 1 [1] => 1 [2] => 1 [3] => 3 [4] => 2 [5] => 6 ) Which doesn't seem right to me. The problem might be with my implementation of the algorithm because I am not sure I understand it correctly. I used this source to implement it: http://www.google.com/books?id=aSiBs6PDm9AC&pg=PA166&dq=lawler%27s+algorithm+code&lr=&hl=sk&cd=4#v=onepage&q=&f=false The description there is a little confusing. For example, I didn't quite get how is the subset D defined (I guess it is arbitrary). Could anyone help me out with this? I have been trying to find some sources with simpler explanation of the algorithm but all sources I found were even more complicated (with math proofs and such) so I am stuck with the link above. Yes, this is a homework, if it wasn't obvious. I still have few weeks to crack this but I have spent few days already trying to get how exactly this algorithm works with no success so I don't think I will get any brighter during that time.

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