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  • how to develop a common pool of functions?

    - by user975234
    I need to develop an application which runs on the web as well as on mobile platform. I want to make something like a directory where i hold my common functions in respect to web and mobile platform. This is the diagram which describes what i exactly want: I just want to know how do i implement this thing? If you can help me with the technical details that would be great! P.S: I am new to web app and stuff!

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  • How to Be a Software Engineer?

    - by Mistrio
    My problem is kind of weird so please bear with me. I have been working in a start up concerned basically with mobile development since my graduation 2 years ago. I develop apps for iOS but it's not really relevant. The start up structure is simply founders developers, with no middle-tier technical supervision or project management whatsoever. A typical project cycle of ours is like this: meet with a client send very vague recruitment to an outsourced graphics designer dig in development right after we get the design, no questions asked then improvise improvise improvise! It's not that we are unaware that stuff like requirements analysis, UML, design patterns, source code control, testing, development methodologies... etc. exist, we just simply don't use them, and I mean like never. The result is usually a clunk of hardly-maintainable yet working code. Despite everything we are literally flourishing with many successful apps on all platforms and bigger clients each project. The thing is, we want the chaos and we're looking for advice. How would you fix our company technically? Given that you can't hire project managers or team leaders just because we are barely 5 developers, so it wouldn't be a justified cost for the founders, but one-time things like courses, books, private training... etc is an option. Lastly, if it's relevant, we are based in Egypt. Thank you a lot in advance.

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  • Don Knuth and MMIXAL vs. Chuck Moore and Forth -- Algorithms and Ideal Machines -- was there cross-pollination / influence in their ideas / work?

    - by AKE
    Question: To what extent is it known (or believed) that Chuck Moore and Don Knuth had influence on each other's thoughts on ideal machines, or their work on algorithms? I'm interested in citations, interviews, articles, links, or any other sort of evidence. It could also be evidence of the form of A and B here suggest that Moore might have borrowed or influenced C and D from Knuth here, or vice versa. (Opinions are of course welcome, but references / links would be better!) Context: Until fairly recently, I have been primarily familiar with Knuth's work on algorithms and computing models, mostly through TAOCP but also through his interviews and other writings. However, the more I have been using Forth, the more I am struck by both the power of a stack-based machine model, and the way in which the spareness of the model makes fundamental algorithmic improvements more readily apparent. A lot of what Knuth has done in fundamental analysis of algorithms has, it seems to me, a very similar flavour, and I can easily imagine that in a parallel universe, Knuth might perhaps have chosen Forth as his computing model. That's the software / algorithms / programming side of things. When it comes to "ideal computing machines", Knuth in the 70s came up with the MIX computer model, and then, collaborating with designers of state-of-the-art RISC chips through the 90s, updated this with the modern MMIX model and its attendant assembly language MMIXAL. Meanwhile, Moore, having been using and refining Forth as a language, but using it on top of whatever processor happened to be in the computer he was programming, began to imagine a world in which the efficiency and value of stack-based programming were reflected in hardware. So he went on in the 80s to develop his own stack-based hardware chips, defining the term MISC (Minimal Instruction Set Computers) along the way, and ending up eventually with the first Forth chip, the MuP21. Both are brilliant men with keen insight into the art of programming and algorithms, and both work at the intersection between algorithms, programs, and bare metal hardware (i.e. hardware without the clutter of operating systems). Which leads me to the headlined question... Question:To what extent is it known (or believed) that Chuck Moore and Don Knuth had influence on each other's thoughts on ideal machines, or their work on algorithms?

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  • How do programmer-seeking employers see Bioinformatics degree?

    - by Max
    I love programming, but I also love biology. Basically Bioinformatics sounds fun to me. However, there is a fat chance that I won't get a Bioinformatics job and will be forced to build my career around regular programming. Therefore a question: does it matter (much) for an employer if he is looking for a regular programmer but finds a Bioinformatics diploma? Or is it the same in the long run as a regular Informatics diploma?

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  • Most efficient way to rebuild a tree structure from data

    - by Ahsan
    Have a question on recursively populating JsTree using the .NET wrapper available via NuGet. Any help would be greatly appreciated. the .NET class JsTree3Node has a property named Children which holds a list of JsTree3Nodes, and the pre-existing table which contains the node structure looks like this NodeId ParentNodeId Data AbsolutePath 1 NULL News /News 2 1 Financial /News/Financial 3 2 StockMarket /News/Financial/StockMarket I have a EF data context from the the database, so my code currently looks like this. var parentNode = new JsTree3Node(Guid.NewGuid().ToString()); foreach(var nodeItem in context.Nodes) { parentNode.Children.Add(nodeItem.Data); // What is the most efficient logic to do this recursively? } as the inline comment says in the above code, what would be the most efficient way to load the JStree data on to the parentNode object. I can change the existing node table to suite the logic so feel free to suggest any changes to improve performance.

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  • Rails Book Suggestions [closed]

    - by Solomon081
    Possible Duplicate: Is there a canonical book on Ruby on Rails? I'm looking to learn Ruby on Rails. I already have a small background in Ruby and don't really need a book that covers both, as I ordered the Pickaxe Book a couple days ago. I recently read some of Beginning Ruby on Rails-Steven Holzner, but abandoned that after seeing multiple statements on SO about how terrible the code in it was, and also the fact that it used Rails 1...Just wondering, what is the best book for an ABSOLUTE BEGINNER in Rails?

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  • Recaptcha php problem [closed]

    - by Sam Gabriel
    Hey guys, I'm using recaptcha and I've got a problem, when a user clicks the signup button it redirects him to the sign up verification page, and here is the code, found on the very top of the web code, that checks the recaptcha entered data. <?php require_once('recaptchalib.php'); $privatekey = "***"; $resp = recaptcha_check_answer ($privatekey, $_SERVER["REMOTE_ADDR"], $_POST["recaptcha_challenge_field"], $_POST["recaptcha_response_field"]); if (!$resp->is_valid) { header('location: signup.php'); } ?> But it seems whatever I type in in the recaptcha box, be it right or wrong, I get redirected to the signup.php page. Here is the recaptcha code in the signup.php page: <?php ini_set('display_errors', 'On'); error_reporting(E_ALL | E_STRICT); require_once('recaptchalib.php'); $publickey = "***"; echo recaptcha_get_html($publickey); ?>

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  • Why should I use Zend_Application?

    - by Billy ONeal
    I've been working on a Zend Framework application which currently does a bunch of things through Zend Application and a few resource plugins written for it. However, looking at this codebase now, it seems to me that using Zend_Application just makes things more complicated; and a plain, more "traditional" bootstrap file would do a better job of being transparent. This is even more the case because the individual components of Zend -- Zend_Controller, Zend_Navigation, etc. -- don't reference Zend_Application at all. Therefore they do things like "Well just call setRoute and be on your way," and the user is left scratching their head as to how to implement that in terms of the application.ini configuration file. This is not to say that one can't figure out what's going on by doing spelunking through the ZF source code. My problem with that approach is that it's to easy to depend on something that's an implementation detail, rather than a contract, and that all it seems to do is add an extra layer of indirection that one must wade through to understand an application. I look at pre ZF 1.8 example code, before Zend_Application existed, and everywhere I see plain bootstrap files that setup the MVC framework and get on their way. The code is clear and easy to understand, even if it is a bit repetitive. I like the DRY concept that Application gets you, but particularly when I'm assuming first people looking at the app's code aren't really familiar with Zend at all, I'm considering blowing away any dependence I have on Zend_Application and returning to a traditional bootstrap file. Now, my concern here is that I don't have much experience doing this, and I don't want to get rid of Zend_Application if it does something particularly important of which I am unaware, or something of that nature. Is there a really good reason I should keep it around?

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  • Idea of an algorithm to detect a website's navigation structure?

    - by Uwe Keim
    Currently I am in the process of developing an importer of any existing, arbitrary (static) HTML website into the upcoming release of our CMS. While the downloading the files is solved successfully, I'm pulling my hair off when it comes to detect a site structure (pages and subpages) purely from the HTML files, without the user specifying additional hints. Basically I want to get a tree like: + Root page 1 + Child page 1 + Child page 2 + Child child page1 + Child page 3 + Root page 2 + Child page 4 + Root page 3 + ... I.e. I want to be able to detect the menu structure from the links inside the pages. This has not to be 100% accurate, but at least I want to achieve more than just a flat list. I thought of looking at multiple pages to see similar areas and identify these as menu areas and parse the links there, but after all I'm not that satisfied with this idea. My question: Can you imagine any algorithm when it comes to detecting such a structure? Update 1: What I'm looking for is not a web spider, but an algorithm do create a logical tree of the relationship of the pages to be able to create pages and subpages inside my CMS when importing them. Update 2: As of Robert's suggestion I'll solve this by starting at the root page, and then simply parse links as you go and treat every link inside a page simply as a child page. Probably I'll recurse not in a deep-first manner but rather in a breadth-first manner to get a more balanced navigation structure.

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  • Wisdom of using open source code in a commercial software product

    - by Mr. Jefferson
    I'm looking at using some open source code in my ASP.NET web app (specifically dapper). Management is not a fan, because open source is seen as a risk that has bitten us before. Apparently previous developers have had to rewrite things after having open-source components fail. The pros seem to be: It does a lot of stuff for me that would otherwise involve either lots of boilerplate code or Microsoft's recommended but slower solution (Entity Framework). Cons: It's complex enough that if it were to fail suddenly in production, I would be hard pressed to fix it. However, it's in use on a much higher-traffic site than mine, so I don't think it'll end up being a high risk portion of the project. What is the consensus here? Is it unwise to use open source code in my project that I don't know/understand as well as I do my own code?

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  • Regarding Microsoft MVC framework and usage [closed]

    - by Thomas
    it will be better if some one tell me that what type of web application should develop using Microsoft MVC framework. i am familiar with web form but not familiar with MS MVC framework. i feel any type of web application can be developed with web form. i search google lot to know the specific reason for using MS MVC framework. i am keen interested to know when i should develop web apps using MS MVC framework and when i should use web form. i will be happy if some one discuss this issue in detail. thanks

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  • Confusion related to sigwait in multiprocess system

    - by user34790
    I am having difficulty in understanding IPC in multiprocess system. I have this system where there are three child processes that send two types of signals to their process group. There are four types of signal handling processes responsible for a particular type of signal. There is this monitoring process which waits for both the signals and then processes accordingly. When I run this program for a while, the monitoring process doesn't seem to pick up the signal as well as the signal handling process. I could see in the log that the signal is only being generated but not handled at all. My code is given below #include <cstdlib> #include <iostream> #include <iomanip> #include <unistd.h> #include <sys/types.h> #include <sys/wait.h> #include <sys/time.h> #include <signal.h> #include <unistd.h> #include <fcntl.h> #include <cstdio> #include <stdlib.h> #include <stdio.h> #include <pthread.h> using namespace std; double timestamp() { struct timeval tp; gettimeofday(&tp, NULL); return (double)tp.tv_sec + tp.tv_usec / 1000000.; } double getinterval() { srand(time(NULL)); int r = rand()%10 + 1; double s = (double)r/100; } int count; int count_1; int count_2; double time_1[10]; double time_2[10]; pid_t senders[1]; pid_t handlers[4]; pid_t reporter; void catcher(int sig) { printf("Signal catcher called for %d",sig); } int main(int argc, char *argv[]) { void signal_catcher_int(int); pid_t pid,w; int status; if(signal(SIGUSR1, SIG_IGN) == SIG_ERR) { perror("1"); return 1; } if(signal(SIGUSR2 ,SIG_IGN) == SIG_ERR) { perror("2"); return 2; } if(signal(SIGINT,signal_catcher_int) == SIG_ERR) { perror("3"); return 2; } //Registering the signal handler for(int i=0; i<4; i++) { if((pid = fork()) == 0) { cout << i << endl; //struct sigaction sigact; sigset_t sigset; int sig; int result = 0; sigemptyset(&sigset); if(i%2 == 0) { if(signal(SIGUSR2, SIG_IGN) == SIG_ERR) { perror("2"); return 2; } sigaddset(&sigset, SIGUSR1); sigprocmask(SIG_BLOCK, &sigset, NULL); } else { if(signal(SIGUSR1, SIG_IGN) == SIG_ERR) { perror("2"); return 2; } sigaddset(&sigset, SIGUSR2); sigprocmask(SIG_BLOCK, &sigset, NULL); } while(true) { int result = sigwait(&sigset, &sig); if(result == 0) { cout << "The caught signal is " << sig << endl; } } exit(0); } else { cout << "Registerd the handler " << pid << endl; handlers[i] = pid; } } //Registering the monitoring process if((pid = fork()) == 0) { sigset_t sigset; int sig; int result = 0; sigemptyset(&sigset); sigaddset(&sigset, SIGUSR1); sigaddset(&sigset, SIGUSR2); sigprocmask(SIG_BLOCK, &sigset, NULL); while(true) { int result = sigwait(&sigset, &sig); if(result == 0) { cout << "The monitored signal is " << sig << endl; } else { cout << "error" << endl; } } } else { reporter = pid; } sleep(3); //Registering the signal generator for(int i=0; i<1; i++) { if((pid = fork()) == 0) { if(signal(SIGUSR1, SIG_IGN) == SIG_ERR) { perror("1"); return 1; } if(signal(SIGUSR2, SIG_IGN) == SIG_ERR) { perror("2"); return 2; } srand(time(0)); while(true) { volatile int signal_id = rand()%2 + 1; cout << "Generating the signal " << signal_id << endl; if(signal_id == 1) { killpg(getpgid(getpid()), SIGUSR1); } else { killpg(getpgid(getpid()), SIGUSR2); } int r = rand()%10 + 1; double s = (double)r/100; sleep(s); } exit(0); } else { cout << "Registered the sender " << pid << endl; senders[i] = pid; } } while(w = wait(&status)) { cout << "Wait on PID " << w << endl; } } void signal_catcher_int(int the_sig) { //cout << "Handling the Ctrl C signal " << endl; for(int i=0; i<1; i++) { kill(senders[i],SIGKILL); } for(int i=0; i<4; i++) { kill(handlers[i],SIGKILL); } kill(reporter,SIGKILL); exit(3); } Any suggestions? Here is a sample of the output as well In the beginning Registerd the handler 9544 Registerd the handler 9545 1 Registerd the handler 9546 Registerd the handler 9547 2 3 0 Registered the sender 9550 Generating the signal 1 The caught signal is 10 The monitored signal is 10 The caught signal is 10 Generating the signal 1 The caught signal is 10 The monitored signal is 10 The caught signal is 10 Generating the signal 1 The caught signal is 10 The monitored signal is 10 The caught signal is 10 Generating the signal 1 The caught signal is 10 The monitored signal is 10 The caught signal is 10 Generating the signal 2 The caught signal is 12 The caught signal is 12 The monitored signal is 12 Generating the signal 2 Generating the signal 2 The caught signal is 12 The caught signal is 12 Generating the signal 1 The caught signal is 12 The monitored signal is 10 The monitored signal is 12 Generating the signal 1 Generating the signal 2 The caught signal is 12 Generating the signal 1 Generating the signal 2 10 The monitored signal is 10 The caught signal is 12 Generating the signal 1 The caught signal is 12 The monitored signal is GenThe caught signal is TheThe caught signal is 10 Generating the signal 2 Later on The monitored signal is GenThe monitored signal is 10 Generating the signal 1 Generating the signal 2 The caught signal is 10 The caught signal is 10 The caught signal is 10 The caught signal is 12 Generating the signal 1 Generating the signal 2 Generating the signal 1 Generating the signal 1 Generating the signal 2 Generating the signal 2 Generating the signal 2 Generating the signal 2 Generating the signal 2 Generating the signal 1 The caught signal is 12 The caught signal is 10 The caught signal is 10 Generating the signal 2 Generating the signal 1 Generating the signal 1 Generating the signal 2 Generating the signal 1 Generating the signal 2 Generating the signal 2 Generating the signal 2 Generating the signal 1 Generating the signal 2 Generating the signal 1 Generating the signal 2 Generating the signal 2 The caught signal is 10 Generating the signal 2 Generating the signal 1 Generating the signal 1 As you can see initially, the signal was generated and handled both by my signal handlers and monitoring processes. But later on the signal was generated a lot, but it was not quite processes in the same magnitude as before. Further I could see very less signal processing by the monitoring process Can anyone please provide some insights. What's going on?

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  • Class Design -- Multiple Calls from One Method or One Call from Multiple Methods?

    - by Andrew
    I've been working on some code recently that interfaces with a CMS we use and it's presented me with a question on class design that I think is applicable in a number of situations. Essentially, what I am doing is extracting information from the CMS and transforming this information into objects that I can use programatically for other purposes. This consists of two steps: Retrieve the data from the CMS (we have a DAL that I use, so this is essentially just specifying what data from the CMS I want--no connection logic or anything like that) Map the parsed data to my own [C#] objects There are basically two ways I can approach this: One call from multiple methods public void MainMethodWhereIDoStuff() { IEnumerable<MyObject> myObjects = GetMyObjects(); // Do other stuff with myObjects } private static IEnumerable<MyObject> GetMyObjects() { IEnumerable<CmsDataItem> cmsDataItems = GetCmsDataItems(); List<MyObject> mappedObjects = new List<MyObject>(); // do stuff to map the CmsDataItems to MyObjects return mappedObjects; } private static IEnumerable<CmsDataItem> GetCmsDataItems() { List<CmsDataItem> cmsDataItems = new List<CmsDataItem>(); // do stuff to get the CmsDataItems I want return cmsDataItems; } Multiple calls from one method public void MainMethodWhereIDoStuff() { IEnumerable<CmsDataItem> cmsDataItems = GetCmsDataItems(); IEnumerable<MyObject> myObjects = GetMyObjects(cmsDataItems); // do stuff with myObjects } private static IEnumerable<MyObject> GetMyObjects(IEnumerable<CmsDataItem> itemsToMap) { // ... } private static IEnumerable<CmsDataItem> GetCmsDataItems() { // ... } I am tempted to say that the latter is better than the former, as GetMyObjects does not depend on GetCmsDataItems, and it is explicit in the calling method the steps that are executed to retrieve the objects (I'm concerned that the first approach is kind of an object-oriented version of spaghetti code). On the other hand, the two helper methods are never going to be used outside of the class, so I'm not sure if it really matters whether one depends on the other. Furthermore, I like the fact that in the first approach the objects can be retrieved from one line-- most likely anyone working with the main method doesn't care how the objects are retrieved, they just need to retrieve the objects, and the "daisy chained" helper methods hide the exact steps needed to retrieve them (in practice, I actually have a few more methods but am still able to retrieve the object collection I want in one line). Is one of these methods right and the other wrong? Or is it simply a matter of preference or context dependent?

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  • Setter Validation can affect performance?

    - by TiagoBrenck
    Whitin a scenario where you use an ORM to map your entities to the DB, and you have setter validations (nullable, date lower than today validation, etc) every time the ORM get a result, it will pass into the setter to instance the object. If I have a grid that usually returns 500 records, I assume that for each record it passes on all validations. If my entity has 5 setter validations, than I have passed in 2.500 validations. Does those 2.500 validations will affect the performance? If was 15.000 validation, it will be different? In my opinion, and according to this answer (http://stackoverflow.com/questions/4893558/calling-setters-from-a-constructor/4893604#4893604), setter validation is usefull than constructors validation. Is there a way to avoid unecessary validation, since I am safe that the values I send to DB when saving the entity wont change until I edit it on my system?

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  • Objective C and ios development training courses feedback

    - by Mutuelinvestor
    I'm thinking about taking an Objective C / iphone/ipad development training course. Pragmatic Studio and Big Nerd Ranch appear to be the key players. I'd love to hear any feed back from anyone who has completed training with Pragmatic, Big Nerd or others. I'd interested in quality of instruction, how much you learned, strengths, weaknesses and any other valuable insights. Its a pretty big financial commitment for me and I want to get the most bang for my buck. Thanks in advance for your input.

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  • How to store generated eigen faces for future face recognition?

    - by user3237134
    My code works in the following manner: 1.First, it obtains several images from the training set 2.After loading these images, we find the normalized faces,mean face and perform several calculation. 3.Next, we ask for the name of an image we want to recognize 4.We then project the input image into the eigenspace, and based on the difference from the eigenfaces we make a decision. 5.Depending on eigen weight vector for each input image we make clusters using kmeans command. Source code i tried: clear all close all clc % number of images on your training set. M=1200; %Chosen std and mean. %It can be any number that it is close to the std and mean of most of the images. um=60; ustd=32; %read and show images(bmp); S=[]; %img matrix for i=1:M str=strcat(int2str(i),'.jpg'); %concatenates two strings that form the name of the image eval('img=imread(str);'); [irow icol d]=size(img); % get the number of rows (N1) and columns (N2) temp=reshape(permute(img,[2,1,3]),[irow*icol,d]); %creates a (N1*N2)x1 matrix S=[S temp]; %X is a N1*N2xM matrix after finishing the sequence %this is our S end %Here we change the mean and std of all images. We normalize all images. %This is done to reduce the error due to lighting conditions. for i=1:size(S,2) temp=double(S(:,i)); m=mean(temp); st=std(temp); S(:,i)=(temp-m)*ustd/st+um; end %show normalized images for i=1:M str=strcat(int2str(i),'.jpg'); img=reshape(S(:,i),icol,irow); img=img'; end %mean image; m=mean(S,2); %obtains the mean of each row instead of each column tmimg=uint8(m); %converts to unsigned 8-bit integer. Values range from 0 to 255 img=reshape(tmimg,icol,irow); %takes the N1*N2x1 vector and creates a N2xN1 matrix img=img'; %creates a N1xN2 matrix by transposing the image. % Change image for manipulation dbx=[]; % A matrix for i=1:M temp=double(S(:,i)); dbx=[dbx temp]; end %Covariance matrix C=A'A, L=AA' A=dbx'; L=A*A'; % vv are the eigenvector for L % dd are the eigenvalue for both L=dbx'*dbx and C=dbx*dbx'; [vv dd]=eig(L); % Sort and eliminate those whose eigenvalue is zero v=[]; d=[]; for i=1:size(vv,2) if(dd(i,i)>1e-4) v=[v vv(:,i)]; d=[d dd(i,i)]; end end %sort, will return an ascending sequence [B index]=sort(d); ind=zeros(size(index)); dtemp=zeros(size(index)); vtemp=zeros(size(v)); len=length(index); for i=1:len dtemp(i)=B(len+1-i); ind(i)=len+1-index(i); vtemp(:,ind(i))=v(:,i); end d=dtemp; v=vtemp; %Normalization of eigenvectors for i=1:size(v,2) %access each column kk=v(:,i); temp=sqrt(sum(kk.^2)); v(:,i)=v(:,i)./temp; end %Eigenvectors of C matrix u=[]; for i=1:size(v,2) temp=sqrt(d(i)); u=[u (dbx*v(:,i))./temp]; end %Normalization of eigenvectors for i=1:size(u,2) kk=u(:,i); temp=sqrt(sum(kk.^2)); u(:,i)=u(:,i)./temp; end % show eigenfaces; for i=1:size(u,2) img=reshape(u(:,i),icol,irow); img=img'; img=histeq(img,255); end % Find the weight of each face in the training set. omega = []; for h=1:size(dbx,2) WW=[]; for i=1:size(u,2) t = u(:,i)'; WeightOfImage = dot(t,dbx(:,h)'); WW = [WW; WeightOfImage]; end omega = [omega WW]; end % Acquire new image % Note: the input image must have a bmp or jpg extension. % It should have the same size as the ones in your training set. % It should be placed on your desktop ed_min=[]; srcFiles = dir('G:\newdatabase\*.jpg'); % the folder in which ur images exists for b = 1 : length(srcFiles) filename = strcat('G:\newdatabase\',srcFiles(b).name); Imgdata = imread(filename); InputImage=Imgdata; InImage=reshape(permute((double(InputImage)),[2,1,3]),[irow*icol,1]); temp=InImage; me=mean(temp); st=std(temp); temp=(temp-me)*ustd/st+um; NormImage = temp; Difference = temp-m; p = []; aa=size(u,2); for i = 1:aa pare = dot(NormImage,u(:,i)); p = [p; pare]; end InImWeight = []; for i=1:size(u,2) t = u(:,i)'; WeightOfInputImage = dot(t,Difference'); InImWeight = [InImWeight; WeightOfInputImage]; end noe=numel(InImWeight); % Find Euclidean distance e=[]; for i=1:size(omega,2) q = omega(:,i); DiffWeight = InImWeight-q; mag = norm(DiffWeight); e = [e mag]; end ed_min=[ed_min MinimumValue]; theta=6.0e+03; %disp(e) z(b,:)=InImWeight; end IDX = kmeans(z,5); clustercount=accumarray(IDX, ones(size(IDX))); disp(clustercount); QUESTIONS: 1.It is working fine for M=50(i.e Training set contains 50 images) but not for M=1200(i.e Training set contains 1200 images).It is not showing any error.There is no output.I waited for 10 min still there is no output. I think it is going infinite loop.What is the problem?Where i was wrong? 2.Instead of running the training set everytime how eigen faces generated are stored so that stored eigen faces are used for future face recoginition for a new input image.So it reduces wastage of time.

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  • C++ Library API Design

    - by johannes
    I'm looking for a good resource for learning about good API design for C++ libraries, looking at shared objects/dlls etc. There are many resources on writing nice APIs, nice classes, templates and so on at source level, but barely anything about putting things together in shared libs and executables. Books like Large-Scale C++ Software Design by John Lakos are interesting but massively outdated. What I'm looking for is advice i.e. on handling templates. With templates in my API I often end up with library code in my executable (or other library) so if I fix a bug in there I can't simply roll out the new library but have to recompile and redistribute all clients of that code. (and yes, I know some solutions like trying to instantiate at least the most common versions inside the library etc.) I'm also looking for other caveats and things to mind for keeping binary compatibility while working on C++ libraries. Is there a good website or book on such things?

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  • Architecture design with MyBatis mappers

    - by Wolf
    I am creating rest web service for providing data. I am using Spring MVC for handling rest requests, and MyBatis for data access. Application should be designed in the way that it should be easy to change the data access implementation (for example to hibernate or something else) and it has to be fast (so I am trying to avoid unnecessary overcomplication of design). Now my question is about the general design of layers. I would normally use DAO interface and then different implementations for different data access strategies, but MyBatis uses interfaces to access the data. So I can think of 2 possible models but I am not sure which one is better or if there is any other nice way: Controller layer - uses Service layer interfaces services are then implemented for each data access stretegy - for example for mybatis: service implementation uses Mapper classes to access data and do whatever it needs to do with them and sends them to controller layer Controller layer - uses Service layer - service layer uses DAO interfaces DAOs are then implemented for each data access strategy - for example for mybatis: DAO class uses mapper interface to access data and sends them to service layer, service layer then do whatever it needs to do with them and sends them to controller layer I prefer the first strategy as it seems to be less complicated, but then I would have to write all of the service code for another data access again. What do you think? Thank You

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  • SQL, moving million records from a database to other database [migrated]

    - by Ryoma
    I am a C# developer, I am not really good with SQL. I have a simple questions here. I need to move more than 50 millions records from a database to other database. I tried to use the import function in ms SQL, however it got stuck because the log was full (I got an error message The transaction log for database 'mydatabase' is full due to 'LOG_BACKUP'). The database recovery model was set to simple. My friend said that importing millions records using task-import data will cause the log to be massive and told me to use loop instead to transfer the data, does anyone know how and why? thanks in advance

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  • MBO in software development

    - by Euphoric
    I just found out our middle sized software development company is going to implement MBO. As a big fan of Agile, I see this as counter-intuitive, because I believe it is impossible to create a objective, that is measurable. Especialy where creativity, experience, knowledge and profesionalism are important traits and expanding those are objectives and goals of many. So my question is, what is your opinion on using MBO in software development? And if there are development companies using MBO, either successfuly or unsucessfuly.

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  • Optimizing hash lookup & memory performance in Go

    - by Moishe
    As an exercise, I'm implementing HashLife in Go. In brief, HashLife works by memoizing nodes in a quadtree so that once a given node's value in the future has been calculated, it can just be looked up instead of being re-calculated. So eg. if you have a node at the 8x8 level, you remember it by its four children (each at the 2x2 level). So next time you see an 8x8 node, when you calculate the next generation, you first check if you've already seen a node with those same four children. This is extended up through all levels of the quadtree, which gives you some pretty amazing optimizations if eg. you're 10 levels above the leaves. Unsurprisingly, it looks like the perfmance crux of this is the lookup of nodes by child-node values. Currently I have a hashmap of {&upper_left_node,&upper_right_node,&lower_left_node,&lower_right_node} -> node So my lookup function is this: func FindNode(ul, ur, ll, lr *Node) *Node { var node *Node var ok bool nc := NodeChildren{ul, ur, ll, lr} node, ok = NodeMap[nc] if ok { return node } node = &Node{ul, ur, ll, lr, 0, ul.Level + 1, nil} NodeMap[nc] = node return node } What I'm trying to figure out is if the "nc := NodeChildren..." line causes a memory allocation each time the function is called. If it does, can I/should I move the declaration to the global scope and just modify the values each time this function is called? Or is there a more efficient way to do this? Any advice/feedback would be welcome. (even coding style nits; this is literally the first thing I've written in Go so I'd love any feedback)

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  • Why should you document code?

    - by Edwin Tripp
    I am a graduate software developer for a financial company that uses an old COBOL-like language/flat-file record storage system. The code is completely undocumented, both code comments and overall system design and there is no help on the web (unused outside the industry). The current developers have been working on the system for between 10 and 30 years and are adamant that documentation is unnecessary as you can just read the code to work out what's going on and that you can't trust comments. Why should such a system be documented?

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  • Developing Web Portal

    - by Ya Basha
    I'm php, Ruby on Rails and HTML5 developer I need some advises and suggestions for a web portal project that I will build from scratch. This is my first time to build a web portal, Which developing scripting language you prefer and why? and how I should start planing my project as it will contains many modules. I'm excited to start building this project and I want to build it in the right way with planing, if you know some web resources that help me decide and plan my project please give them to me. Best Regards,

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  • Should I organize my folders by business domain or by technical domain?

    - by Florian Margaine
    For example, if I'm using some MVC-like architecture, which folder structure should I use: domain1/ controller model view domain2/ controller model view Or: controllers/ domain1 domain2 models/ domain1 domain2 views/ domain1 domain2 I deliberately left out file extensions to keep this question language-agnostic. Personally, I'd prefer to separate by business domain (gut feeling), but I see that most/many frameworks separate by technical domain. Why whould I choose one over the other?

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  • Does it matter the direction of a Huffman's tree child node?

    - by Omega
    So, I'm on my quest about creating a Java implementation of Huffman's algorithm for compressing/decompressing files (as you might know, ever since Why create a Huffman tree per character instead of a Node?) for a school assignment. I now have a better understanding of how is this thing supposed to work. Wikipedia has a great-looking algorithm here that seemed to make my life way easier. Taken from http://en.wikipedia.org/wiki/Huffman_coding: Create a leaf node for each symbol and add it to the priority queue. While there is more than one node in the queue: Remove the two nodes of highest priority (lowest probability) from the queue Create a new internal node with these two nodes as children and with probability equal to the sum of the two nodes' probabilities. Add the new node to the queue. The remaining node is the root node and the tree is complete. It looks simple and great. However, it left me wondering: when I "merge" two nodes (make them children of a new internal node), does it even matter what direction (left or right) will each node be afterwards? I still don't fully understand Huffman coding, and I'm not very sure if there is a criteria used to tell whether a node should go to the right or to the left. I assumed that, perhaps the highest-frequency node would go to the right, but I've seen some Huffman trees in the web that don't seem to follow such criteria. For instance, Wikipedia's example image http://upload.wikimedia.org/wikipedia/commons/thumb/8/82/Huffman_tree_2.svg/625px-Huffman_tree_2.svg.png seems to put the highest ones to the right. But other images like this one http://thalia.spec.gmu.edu/~pparis/classes/notes_101/img25.gif has them all to the left. However, they're never mixed up in the same image (some to the right and others to the left). So, does it matter? Why?

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