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  • Using jQuery to Dynamically Insert Into List Alphabetically

    - by Dex
    I have two ordered lists next to each other. When I take a node out of one list I want to insert it alphabetically into the other list. The catch is that I want to take just the one element out and place it back in the other list without refreshing the entire list. The strange thing is that when I insert into the list on the right, it works fine, but when I insert back into the list on the left, the order never comes out right. I have also tried reading everything into an array and sorting it there just in case the children() method isn't returning things in the order they are displayed, but I still get the same results. Here is my jQuery: function moveNode(node, to_list, order_by){ rightful_index = 1; $(to_list) .children() .each(function(){ var ordering_field = (order_by == "A") ? "ingredient_display" : "local_counter"; var compA = $(node).attr(ordering_field).toUpperCase(); var compB = $(this).attr(ordering_field).toUpperCase(); var C = ((compA > compB) ? 1 : 0); if( C == 1 ){ rightful_index++; } }); if(rightful_index > $(to_list).children().length){ $(node).fadeOut("fast", function(){ $(to_list).append($(node)); $(node).fadeIn("fast"); }); }else{ $(node).fadeOut("fast", function(){ $(to_list + " li:nth-child(" + rightful_index + ")").before($(node)); $(node).fadeIn("fast"); }); } } Here is what my html looks like: <ol> <li ingredient_display="Enriched Pasta" ingredient_id="101635" local_counter="1"> <span class="rank">1</span> <span class="rounded-corners"> <span class="plus_sign">&nbsp;&nbsp;+&nbsp;&nbsp;</span> <div class="ingredient">Enriched Pasta</div> <span class="minus_sign">&nbsp;&nbsp;-&nbsp;&nbsp;</span> </span> </li> </ol>

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  • 301 redirect vs parking

    - by Pat
    I have several domain names registered, each a slight variant of each other. E.g, fastcar.com fast-car.com fastcar.co.uk fast-car.co.uk etc.. I don't wish to be penalized for duplicate content or spammy links by any of the major search engines. Should I park them all directly on the main domain I wish to promote, 301 redirect them to the main domain or not use them at all? Thanks

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  • Alpha-Beta cutoff

    - by Becky
    I understand the basics of this search, however the beta cut-off part is confusing me, when beta <= value of alphabeta I can either return beta, break, or continue the loop. return beta doesn't seem to work properly at all, it returns the wrong players move for a different state of the board (further into the search tree) break seems to work correctly, it is very fast but it seems a bit TOO fast continue is a lot slower than break but it seems more correct...I'm guessing this is the right way but pseudocode on google all use 'break' but because this is pseudocode I'm not sure what they mean by 'break'

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  • JQuery Treeview causes browser crash with certain parameters

    - by IP
    I have the following code, which causes Chrome and Safari to crash (Aw Snap in Chrome) jQuery(".filetree").treeview({ animated: "fast", collapsed: true, unique: true, persist: "cookie", toggle: function() { } }); If I change it to this: jQuery(".filetree").treeview({ animated: "fast", toggle: function() { } }); It doesn't crash...any ideas?

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  • Small objects allocator

    - by Felics
    Hello, Has anybody used SmallObjectAllocator from Modern C++ Design by Andrei Alexandrescu in a big project? I want to implement this allocator but I need some opinions about it before using it in my project. I made some tests and it seems very fast, but the tests were made in a small test environment. I want to know how fast it is when are lots of small objects(like events, smart pointers, etc) and how much extra memory it uses.

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  • Is there a good Fogbugz client for Windows

    - by Sebastian
    Funnily enough, I already found some pointers and a thread to an OSX client for Fogbugz. Here I am looking for a Windows client. I know there are web browsers for Windows, but I am looking for fast editing; fast changing of attributes ("one click"); zapping through cases and edits in milliseconds; no waiting for HTTP round trips, just pure speed. Are there any solutions for this?

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  • Dynamic data-entry value store

    - by simendsjo
    I'm creating a data-entry application where users are allowed to create the entry schema. My first version of this just created a single table per entry schema with each entry spanning a single or multiple columns (for complex types) with the appropriate data type. This allowed for "fast" querying (on small datasets as I didn't index all columns) and simple synchronization where the data-entry was distributed on several databases. I'm not quite happy with this solution though; the only positive thing is the simplicity... I can only store a fixed number of columns. I need to create indexes on all columns. I need to recreate the table on schema changes. Some of my key design criterias are: Very fast querying (Using a simple domain specific query language) Writes doesn't have to be fast Many concurrent users Schemas will change often Schemas might contain many thousand columns The data-entries might be distributed and needs syncronization. Preferable MySQL and SQLite - Databases like DB2 and Oracle is out of the question. Using .Net/Mono I've been thinking of a couple of possible designs, but none of them seems like a good choice. Solution 1: Union like table containing a Type column and one nullable column per type. This avoids joins, but will definitly use a lot of space. Solution 2: Key/value store. All values are stored as string and converted when needed. Also use a lot of space, and of course, I hate having to convert everything to string. Solution 3: Use an xml database or store values as xml. Without any experience I would think this is quite slow (at least for the relational model unless there is some very good xpath support). I also would like to avoid an xml database as other parts of the application fits better as a relational model, and being able to join the data is helpful. I cannot help to think that someone has solved (some of) this already, but I'm unable to find anything. Not quite sure what to search for either... I know market research is doing something like this for their questionnaires, but there are few open source implementations, and the ones I've found doesn't quite fit the bill. PSPP has much of the logic I'm thinking of; primitive column types, many columns, many rows, fast querying and merging. Too bad it doesn't work against a database.. And of course... I don't need 99% of the provided functionality, but a lot of stuff not included. I'm not sure this is the right place to ask such a design related question, but I hope someone here has some tips, know of any existing work, or can point me to a better place to ask such a question. Thanks in advance!

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  • What's a good matrix manipulation library available for C ?

    - by banister
    Hi, I am doing a lot of image processing in C and I need a good, reasonably lightweight, and above all FAST matrix manipulation library. I am mostly focussing on affine transformations and matrix inversions, so i do not need anything too sophisticated or bloated. Primarily I would like something that is very fast (using SSE perhaps?), with a clean API and (hopefully) prepackaged by many of the unix package management systems. Note this is for C not for C++. Thanks :)

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  • Are there any protocols/standards on top of TCP optimized for high throughput and low latency?

    - by Nosrama
    Are there any protocols/standards that work over TCP that are optimized for high throughput and low latency? The only one I can think of is FAST. At the moment I have devised just a simple text-based protocol delimited by special characters. I'd like to adopt a protocol which is designed for fast transfer and supports perhaps compression and minification of the data that travels over the TCP socket.

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  • Does the Python 3 interpreter have a JIT feature?

    - by guz
    I found that when I ask something more to Python, python doesn't use my machine resource at 100% and it's not really fast, it's fast if compared to many other interpreted languages, but when compared to compiled languages i think that the difference is really remarkable. It's possible to speedup things with a JIT compiler in Python 3 ? Usually a JIT compiler is the only thing that can improve performances in interpreted languages, so i'm referring to this one, if other solutions are available i would love to accept new answers.

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  • Very difficult question !

    - by cibercitizen1
    I'm absolutely impressed by how fast the questions are answered. Some guys seems to be spending all day long waiting for questions: congratulations ! Your help is very appreciated, really. but ... I guess you don't work, don't have friends, or family, even you don't sleep at all? Do you? Or how do you manage to be so fast?

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  • Database design (MySql)::should we put html data in text field inside database table or more efficie

    - by meyosef
    Hi, We building big Web Application and we use mysql, we want to make mysql database more fast. Some of us think if we will put message html body inside table and not inside text.txt in will make database heavy and not fast. Thanks, *Part of main table that hold message: option 1:hold html message body inside database message { id (int) subject (varchar) body (text) } option 2: hold html message body inside body1.txt file message { id (int) subject (varchar) file_body_path (varchar) } *

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  • Random selection in jQuery

    - by danit
    Im using the following function to hide a series of forms on a page: $('.ask').toggle(function() { $(this).text('-').next('.addtitle').slideDown('fast'); }, function() { $(this).text('+').next('.addtitle').slideUp('fast'); }); There can be anything from 0 to 5 forms on the page all with the class .ask What I want to be able to do is to select one form NOT to hide, so the jQuery needs to hide all put one of the forms on the page randomly. How can I achieve this?

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  • show div for a set time, then hide it

    - by Patrick
    Im using jquery for various things on my site, but one thing im not sure how to do, is have it show an element, then wait X seconds, and hide the element. $('#form').ajaxForm(function() { $('#cartcontents').fadeOut("fast").load('cart.php').fadeIn("fast"); }); That's the JavaScript that I'm using now. How could I have it (when the form submits) display the div #notice for 5 seconds, then fadeOut?

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  • Returning an error code in Erlang

    - by Zubair
    I'm writing some Erlang code and I'm very unsure whether I should let everything fail fast. One problem I find with fail fast is that for the developer/user the exception generated is pretty meaningless. Any idea what I should return which would not give esoteric and hard to read stack traces?

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  • Huge performance difference between two web servers, odd behavior seen using process monitor

    - by Francis Gagnon
    We have two Coldfusion servers that have a huge performance difference running the exact same code on the exact same input data. The code in questions instantiates a large amount of CFCs (Coldfusion Components, which are similar to objects in OOP languages). I compared the two servers by running Process Monitor and then calling the problematic code on both machines. I learned two things. First, Coldfusion opens CFC files every time it instantiates an object. Both servers do this, so it cannot be the cause of the performance difference. Second, the fast server opens the CFC files directly while the server with the performance problem seems to navigate its way through the path until it reaches the desired CFC file. It does this for every file, even the ones it has previously loaded, and because the code instantiates so many CFCs it becomes very slow. See below the partial Promon traces that show this behavior. It can take over 60 seconds for the slow server to do what the fast one does in 2 seconds. Can anyone tell me what causes this behavior? Is it a Coldfusion setting? Since Coldfusion runs on top of Java, is it a Java setting? Is it an OS option? The fast server is running Windows XP and I think the slow server is a Windows Server 2003. Bonus question: Coldfusion doesn't seem to perform any READ FILE operations on any of the CFC or CFM files. How can this be? Sample of the fast server opening CFC files: 11:25:14.5588975 jrun.exe QueryOpen C:\CF\wwwroot\APP\com\HtmlUtils.cfc 11:25:14.5592758 jrun.exe CreateFile C:\CF\wwwroot\APP\com\HtmlUtils.cfc 11:25:14.5595024 jrun.exe QueryBasicInformationFile C:\CF\wwwroot\APP\com\HtmlUtils.cfc 11:25:14.5595940 jrun.exe CloseFile C:\CF\wwwroot\APP\com\HtmlUtils.cfc 11:25:14.5599628 jrun.exe CreateFile C:\CF\wwwroot\APP\com\HtmlUtils.cfc 11:25:14.5601600 jrun.exe QueryBasicInformationFile C:\CF\wwwroot\APP\com\HtmlUtils.cfc 11:25:14.5602463 jrun.exe CloseFile C:\CF\wwwroot\APP\com\HtmlUtils.cfc Equivalent sample of the slow server opening CFC files: 11:15:08.1249230 jrun.exe CreateFile D:\ 11:15:08.1250100 jrun.exe QueryDirectory D:\org 11:15:08.1252852 jrun.exe CloseFile D:\ 11:15:08.1259670 jrun.exe CreateFile D:\org 11:15:08.1260319 jrun.exe QueryDirectory D:\org\cli 11:15:08.1260769 jrun.exe CloseFile D:\org 11:15:08.1269451 jrun.exe CreateFile D:\org\cli 11:15:08.1270613 jrun.exe QueryDirectory D:\org\cli\cpn 11:15:08.1271140 jrun.exe CloseFile D:\org\cli 11:15:08.1279312 jrun.exe CreateFile D:\org\cli\cpn 11:15:08.1280086 jrun.exe QueryDirectory D:\org\cli\cpn\APP 11:15:08.1280789 jrun.exe CloseFile D:\org\cli\cpn 11:15:08.1291034 jrun.exe CreateFile D:\org\cli\cpn\APP 11:15:08.1291709 jrun.exe QueryDirectory D:\org\cli\cpn\APP\com 11:15:08.1292224 jrun.exe CloseFile D:\org\cli\cpn\APP 11:15:08.1300568 jrun.exe CreateFile D:\org\cli\cpn\APP\com 11:15:08.1301321 jrun.exe QueryDirectory D:\org\cli\cpn\APP\com\HtmlUtils.cfc 11:15:08.1301843 jrun.exe CloseFile D:\org\cli\cpn\APP\com 11:15:08.1312049 jrun.exe CreateFile D:\org\cli\cpn\APP\com\HtmlUtils.cfc 11:15:08.1314409 jrun.exe QueryBasicInformationFile D:\org\cli\cpn\APP\com\HtmlUtils.cfc 11:15:08.1314633 jrun.exe CloseFile D:\org\cli\cpn\APP\com\HtmlUtils.cfc 11:15:08.1315881 jrun.exe CreateFile D:\ 11:15:08.1316379 jrun.exe QueryDirectory D:\org 11:15:08.1316926 jrun.exe CloseFile D:\ 11:15:08.1330951 jrun.exe CreateFile D:\org 11:15:08.1338656 jrun.exe QueryDirectory D:\org\cli 11:15:08.1339118 jrun.exe CloseFile D:\org 11:15:08.1526468 jrun.exe CreateFile D:\org\cli 11:15:08.1527295 jrun.exe QueryDirectory D:\org\cli\cpn 11:15:08.1527989 jrun.exe CloseFile D:\org\cli 11:15:08.1531977 jrun.exe CreateFile D:\org\cli\cpn 11:15:08.1532589 jrun.exe QueryDirectory D:\org\cli\cpn\APP 11:15:08.1533575 jrun.exe CloseFile D:\org\cli\cpn 11:15:08.1538457 jrun.exe CreateFile D:\org\cli\cpn\APP 11:15:08.1539083 jrun.exe QueryDirectory D:\org\cli\cpn\APP\com 11:15:08.1539553 jrun.exe CloseFile D:\org\cli\cpn\APP 11:15:08.1544126 jrun.exe CreateFile D:\org\cli\cpn\APP\com 11:15:08.1544980 jrun.exe QueryDirectory D:\org\cli\cpn\APP\com\HtmlUtils.cfc 11:15:08.1545482 jrun.exe CloseFile D:\org\cli\cpn\APP\com 11:15:08.1551034 jrun.exe CreateFile D:\org\cli\cpn\APP\com\HtmlUtils.cfc 11:15:08.1552878 jrun.exe QueryBasicInformationFile D:\org\cli\cpn\APP\com\HtmlUtils.cfc 11:15:08.1553044 jrun.exe CloseFile D:\org\cli\cpn\APP\com\HtmlUtils.cfc Thanks

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  • Does this prove a network bandwidth bottleneck?

    - by Yuji Tomita
    I've incorrectly assumed that my internal AB testing means my server can handle 1k concurrency @3k hits per second. My theory at at the moment is that the network is the bottleneck. The server can't send enough data fast enough. External testing from blitz.io at 1k concurrency shows my hits/s capping off at 180, with pages taking longer and longer to respond as the server is only able to return 180 per second. I've served a blank file from nginx and benched it: it scales 1:1 with concurrency. Now to rule out IO / memcached bottlenecks (nginx normally pulls from memcached), I serve up a static version of the cached page from the filesystem. The results are very similar to my original test; I'm capped at around 180 RPS. Splitting the HTML page in half gives me double the RPS, so it's definitely limited by the size of the page. If I internally ApacheBench from the local server, I get consistent results of around 4k RPS on both the Full Page and the Half Page, at high transfer rates. Transfer rate: 62586.14 [Kbytes/sec] received If I AB from an external server, I get around 180RPS - same as the blitz.io results. How do I know it's not intentional throttling? If I benchmark from multiple external servers, all results become poor which leads me to believe the problem is in MY servers outbound traffic, not a download speed issue with my benchmarking servers / blitz.io. So I'm back to my conclusion that my server can't send data fast enough. Am I right? Are there other ways to interpret this data? Is the solution/optimization to set up multiple servers + load balancing that can each serve 180 hits per second? I'm quite new to server optimization, so I'd appreciate any confirmation interpreting this data. Outbound traffic Here's more information about the outbound bandwidth: The network graph shows a maximum output of 16 Mb/s: 16 megabits per second. Doesn't sound like much at all. Due to a suggestion about throttling, I looked into this and found that linode has a 50mbps cap (which I'm not even close to hitting, apparently). I had it raised to 100mbps. Since linode caps my traffic, and I'm not even hitting it, does this mean that my server should indeed be capable of outputting up to 100mbps but is limited by some other internal bottleneck? I just don't understand how networks at this large of a scale work; can they literally send data as fast as they can read from the HDD? Is the network pipe that big? In conclusion 1: Based on the above, I'm thinking I can definitely raise my 180RPS by adding an nginx load balancer on top of a multi nginx server setup at exactly 180RPS per server behind the LB. 2: If linode has a 50/100mbit limit that I'm not hitting at all, there must be something I can do to hit that limit with my single server setup. If I can read / transmit data fast enough locally, and linode even bothers to have a 50mbit/100mbit cap, there must be an internal bottleneck that's not allowing me to hit those caps that I'm not sure how to detect. Correct? I realize the question is huge and vague now, but I'm not sure how to condense it. Any input is appreciated on any conclusion I've made.

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  • Does the .NET Framework need to be reoptimized after upgrading to a new CPU microarchitecture?

    - by Louis
    I believe that the .NET Framework will optimize certain binaries targeting features specific to the machine it's installed on. After changing the CPU from an Intel Nehalem to a Haswell chip, should the optimization be run again manually? If so, what is the process for that? Between generations here are some notable additions: Westmere: AES instruction set Sandy Bridge: Advanced Vector Extensions Ivy Bridge: RdRand (hardware random number generator), F16C (16-bit Floating-point conversion instructions) Haswell: Haswell New Instructions (includes Advanced Vector Extensions 2 (AVX2), gather, BMI1, BMI2, ABM and FMA3 support) So my, albeit naive, thought process was that the optimizations could take advantage of these in general cases. For example, perhaps calls to the Random library could utilize the hardware-RNG on Ivy Bridge and later models.

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  • How do you traverse and store XML in Blackberry Java app?

    - by Greg
    I'm having a problem accessing the contents of an XML document. My goal is this: Take an XML source and parse it into a fair equivalent of an associative array, then store it as a persistable object. the xml is pretty simple: <root> <element> <category_id>1</category_id> <name>Cars</name> </element> <element> <category_id>2</category_id> <name>Boats</name> </element> </root> Basic java class below. I'm pretty much just calling save(xml) after http response above. Yes, the xml is properly formatted. import java.io.IOException; import java.util.Hashtable; import org.w3c.dom.Document; import org.w3c.dom.Node; import org.w3c.dom.NodeList; import java.util.Vector; import net.rim.device.api.system.PersistentObject; import net.rim.device.api.system.PersistentStore; import net.rim.device.api.xml.parsers.DocumentBuilder; import net.rim.device.api.xml.parsers.DocumentBuilderFactory; public class database{ private static PersistentObject storeVenue; static final long key = 0x2ba5f8081f7ef332L; public Hashtable hashtable; public Vector venue_list; String _node,_element; public database() { storeVenue = PersistentStore.getPersistentObject(key); } public void save(Document xml) { venue_list = new Vector(); storeVenue.setContents(venue_list); Hashtable categories = new Hashtable(); try{ DocumentBuilderFactory docBuilderFactory = DocumentBuilderFactory. newInstance(); DocumentBuilder docBuilder = docBuilderFactory.newDocumentBuilder(); docBuilder.isValidating(); xml.getDocumentElement ().normalize (); NodeList list=xml.getElementsByTagName("*"); _node=new String(); _element = new String(); for (int i=0;i<list.getLength();i++){ Node value=list.item(i).getChildNodes().item(0); _node=list.item(i).getNodeName(); _element=value.getNodeValue(); categories.put(_element, _node); } } catch (Exception e){ System.out.println(e.toString()); } venue_list.addElement(categories); storeVenue.commit(); } The code above is the work in progress, and is most likely heavily flawed. However, I have been at this for days now. I can never seem to get all child nodes, or the name / value pair. When I print out the vector as a string, I usually end up with results like this: [{ = root, = element}] and that's it. No "category_id", no "name" Ideally, I would end up with something like [{1 = cars, 2 = boats}] Any help is appreciated. Thanks

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  • Identifier is undefined

    - by hawk
    I wrote the following code in C++ using VS2012 Express. void ac_search( uint num_patterns, uint pattern_length, const char *patterns, uint num_records, uint record_length, const char *records, int *matches, Node* trie) { // Irrelevant code omitted. } vector<int> ac_benchmark_search( uint num_patterns, uint pattern_length, const char *patterns, uint num_records, uint record_length, const char *records, double &time) { // Prepare the container for the results vector<int> matches(num_records * num_patterns); Trie T; Node* trie = T.addWord(records, num_records, record_length); // error line ac_search(num_patterns, pattern_length, patterns, num_records, record_length, records, matches.data(), trie); // Irrelevant code omitted. return matches; } I get the error identifier "ac_search" is undefined at the function invoking line. I am a bit confused here. because the function ac_search is declared as a global (not inside any container). Why can't I call it at this place? Am I missing something? Update I tried ignore irrelevant code and then included it gradually and found that everything is fine until I include the outer loop of ac_search I get the aforementioned error. here is updated code of the function ac_search: void ac_cpu_string_search(uint num_patterns, uint pattern_length, const char *patterns, uint num_records, uint record_length, const char *records, int *matches, Node* trie) { // Loop over all records //for (uint record_number = 0; record_number < num_records; ++record_number) //{ // // Loop over all patterns for (uint pattern_number = 0; pattern_number < num_patterns; ++pattern_number) { // Execute string search const char *ptr_record = &records[record_number * record_length]; const char *ptr_match = std::strstr(ptr_record, &patterns[pattern_number * pattern_length]); // If pattern was found, then calculate offset, otherwise result is -1 if (ptr_match) { matches[record_number * num_patterns + pattern_number] = static_cast<int>(std::distance(ptr_record, ptr_match)); } else { matches[record_number * num_patterns + pattern_number] = -1; } // } //} } Update 2 I think the error has something to do with the function addWord which belongs to the class Trie. When I commented out this function, I did not get the error anymore. Node* Trie::addWord(const char *records, uint num_records, uint record_length) { // Loop over all records for (uint record_number = 0; record_number < num_records; ++record_number) { const char *ptr_record = &records[record_number * record_length]; string s = ptr_record; Node* current = root; if ( s.length() == 0 ) { current->setWordMarker(); // an empty word return; } for ( int i = 0; i < s.length(); i++ ) { Node* child = current->findChild(s[i]); if ( child != NULL ) { current = child; } else { Node* tmp = new Node(); tmp->setContent(s[i]); current->appendChild(tmp); current = tmp; } if ( i == s.length() - 1 ) current->setWordMarker(); } return current; } void ac_search( uint num_patterns, uint pattern_length, const char *patterns, uint num_records, uint record_length, const char *records, int *matches, Node* trie) { // Irrelevant code omitted. } vector<int> ac_benchmark_search( uint num_patterns, uint pattern_length, const char *patterns, uint num_records, uint record_length, const char *records, double &time) { // Prepare the container for the results vector<int> matches(num_records * num_patterns); Trie T; Node* trie = T.addWord(records, num_records, record_length); // error line ac_search(num_patterns, pattern_length, patterns, num_records, record_length, records, matches.data(), trie); // Irrelevant code omitted. return matches; }

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  • STL find performs bettern than hand-crafter loop

    - by dusha
    Hello all, I have some question. Given the following C++ code fragment: #include <boost/progress.hpp> #include <vector> #include <algorithm> #include <numeric> #include <iostream> struct incrementor { incrementor() : curr_() {} unsigned int operator()() { return curr_++; } private: unsigned int curr_; }; template<class Vec> char const* value_found(Vec const& v, typename Vec::const_iterator i) { return i==v.end() ? "no" : "yes"; } template<class Vec> typename Vec::const_iterator find1(Vec const& v, typename Vec::value_type val) { return find(v.begin(), v.end(), val); } template<class Vec> typename Vec::const_iterator find2(Vec const& v, typename Vec::value_type val) { for(typename Vec::const_iterator i=v.begin(), end=v.end(); i<end; ++i) if(*i==val) return i; return v.end(); } int main() { using namespace std; typedef vector<unsigned int>::const_iterator iter; vector<unsigned int> vec; vec.reserve(10000000); boost::progress_timer pt; generate_n(back_inserter(vec), vec.capacity(), incrementor()); //added this line, to avoid any doubts, that compiler is able to // guess the data is sorted random_shuffle(vec.begin(), vec.end()); cout << "value generation required: " << pt.elapsed() << endl; double d; pt.restart(); iter found=find1(vec, vec.capacity()); d=pt.elapsed(); cout << "first search required: " << d << endl; cout << "first search found value: " << value_found(vec, found)<< endl; pt.restart(); found=find2(vec, vec.capacity()); d=pt.elapsed(); cout << "second search required: " << d << endl; cout << "second search found value: " << value_found(vec, found)<< endl; return 0; } On my machine (Intel i7, Windows Vista) STL find (call via find1) runs about 10 times faster than the hand-crafted loop (call via find2). I first thought that Visual C++ performs some kind of vectorization (may be I am mistaken here), but as far as I can see assembly does not look the way it uses vectorization. Why is STL loop faster? Hand-crafted loop is identical to the loop from the STL-find body. I was asked to post program's output. Without shuffle: value generation required: 0.078 first search required: 0.008 first search found value: no second search required: 0.098 second search found value: no With shuffle (caching effects): value generation required: 1.454 first search required: 0.009 first search found value: no second search required: 0.044 second search found value: no Many thanks, dusha. P.S. I return the iterator and write out the result (found or not), because I would like to prevent compiler optimization, that it thinks the loop is not required at all. The searched value is obviously not in the vector.

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  • Can't get Jacobi algorithm to work in Objective-C

    - by Chris Long
    Hi, For some reason, I can't get this program to work. I've had other CS majors look at it and they can't figure it out either. This program performs the Jacobi algorithm (you can see step-by-step instructions and a MATLAB implementation here). BTW, it's different from the Wikipedia article of the same name. Since NSArray is one-dimensional, I added a method that makes it act like a two-dimensional C array. After running the Jacobi algorithm many times, the diagonal entries in the NSArray (i[0][0], i[1][1], etc.) are supposed to get bigger and the others approach 0. For some reason though, they all increase exponentially. For instance, i[2][4] should equal 0.0000009, not 9999999, while i[2][2] should be big. Thanks in advance, Chris NSArray+Matrix.m @implementation NSArray (Matrix) @dynamic offValue, transposed; - (double)offValue { double sum = 0.0; for ( MatrixItem *item in self ) if ( item.nonDiagonal ) sum += pow( item.value, 2.0 ); return sum; } - (NSMutableArray *)transposed { NSMutableArray *transpose = [[[NSMutableArray alloc] init] autorelease]; int i, j; for ( i = 0; i < 5; i++ ) { for ( j = 0; j < 5; j++ ) { [transpose addObject:[self objectAtRow:j andColumn:i]]; } } return transpose; } - (id)objectAtRow:(NSUInteger)row andColumn:(NSUInteger)column { NSUInteger index = 5 * row + column; return [self objectAtIndex:index]; } - (NSMutableArray *)multiplyWithMatrix:(NSArray *)array { NSMutableArray *result = [[NSMutableArray alloc] init]; int i = 0, j = 0, k = 0; double value; for ( i = 0; i < 5; i++ ) { value = 0.0; for ( j = 0; j < 5; j++ ) { for ( k = 0; k < 5; k++ ) { MatrixItem *firstItem = [self objectAtRow:i andColumn:k]; MatrixItem *secondItem = [array objectAtRow:k andColumn:j]; value += firstItem.value * secondItem.value; } MatrixItem *item = [[MatrixItem alloc] initWithValue:value]; item.row = i; item.column = j; [result addObject:item]; } } return result; } @end Jacobi_AlgorithmAppDelegate.m // ... - (void)jacobiAlgorithmWithEntry:(MatrixItem *)entry { MatrixItem *b11 = [matrix objectAtRow:entry.row andColumn:entry.row]; MatrixItem *b22 = [matrix objectAtRow:entry.column andColumn:entry.column]; double muPlus = ( b22.value + b11.value ) / 2.0; muPlus += sqrt( pow((b22.value - b11.value), 2.0) + 4.0 * pow(entry.value, 2.0) ); Vector *u1 = [[[Vector alloc] initWithX:(-1.0 * entry.value) andY:(b11.value - muPlus)] autorelease]; [u1 normalize]; Vector *u2 = [[[Vector alloc] initWithX:-u1.y andY:u1.x] autorelease]; NSMutableArray *g = [[[NSMutableArray alloc] init] autorelease]; for ( int i = 0; i <= 24; i++ ) { MatrixItem *item = [[[MatrixItem alloc] init] autorelease]; if ( i == 6*entry.row ) item.value = u1.x; else if ( i == 6*entry.column ) item.value = u2.y; else if ( i == ( 5*entry.row + entry.column ) || i == ( 5*entry.column + entry.row ) ) item.value = u1.y; else if ( i % 6 == 0 ) item.value = 1.0; else item.value = 0.0; [g addObject:item]; } NSMutableArray *firstResult = [[g.transposed multiplyWithMatrix:matrix] autorelease]; matrix = [firstResult multiplyWithMatrix:g]; } // ...

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