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  • Speed up math code in C# by writing a C dll?

    - by Projectile Fish
    I have a very large nested for loop in which some multiplications and additions are performed on floating point numbers. for (int i = 0; i < length1; i++) { s = GetS(i); c = GetC(i); for(int j = 0; j < length2; j++) { double oldU = u[j]; u[j] = c * oldU + s * omega[i][j]; omega[i][j] = c * omega[i][j] - s * oldU; } } This loop is taking up the majority of my processing time and is a bottleneck. Would I be likely to see any speed improvements if I rewrite this loop in C and interface to it from C#?

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  • PHP Class Question

    - by Jerry
    Hi all I am trying to build a PHP class to check the username and password in MySql. I am getting "mysql_query(): supplied argument is not a valid MySQL-Link resource in D:\2010Portfolio\football\main.php on line 38" database has errors:" message. When I move my userQuery code out of my Class, it works fine. Only if it is inside my Class. I am not sure if the problem is that I don't build the connection to mysql inside my Class or not. Thanks for any helps!! Here is my code <?php $userName=$_POST['userName']; $userPw=$_POST['password']; class checkUsers { public $userName; public $userPw; function checkUsers($userName='', $userPw=''){ $this->userName=$userName; $this->userPw=$userPw; } function check1(){ if (empty($this->userName) || empty($this->userPw)){ $message="<strong>Please Enter Username and Password</strong>"; }else{ //line 38 is next line $userQuery=mysql_query("SELECT userName, userPw FROM user WHERE userName='$this->userName' and userPw='$this->userPw'", $connection); if (!$userQuery){ die("database has errors: ". mysql_error()); } if(mysql_num_rows($userQuery)==0){ $message="Please enter valid username and password"; } }//end empty check return $message; }//end check1 method }//end Class $checkUser=new checkUsers($userName, $userPw); echo $checkUser->check1(); ?> I appreciate any helps!!!!

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  • integer division in php

    - by oezi
    hi guys, i'm looking for the fastest way to do an integer division in php. for example, 5 / 2 schould be 4 | 6 / 2 should be 3 and so on. if i simply do this, php will return 2.5 in the first case, the only solution i could find was using intval($my_number/2) - wich isn't as fast as i want it to be (but gives the expected results). can anyone help me out with this?

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  • Jmeter- HTTP Cache Manager, Unable to cache everything what it is being cached by Browser

    - by chinmay brahma
    I used HTTP Chache Manager to Cache files which are being cached in browser. I am successful of doing it for some of the pages. Number of files being cached in Jmeter is equal to Number of files being cached by browser. But in some cases : I found number files being cached is lesser than the files being cached by browser. Using Jmeter I found only 5 files are being cached but in real browser 12 files are getting cached. Thanks in advance

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  • MySQL InnoDB Cascade Rule that looks at 2 columns?

    - by Travis
    I have the following MySQL InnoDB tables... TABLE foldersA ( ID title ) TABLE foldersB ( ID title ) TABLE records ( ID folderID folderType title ) folderID in table "records" can point to ID in either "foldersA" or "foldersB" depending on the value of folderType. (0 or 1). I am wondering: Is there a way to create a CASCADE rule such that the appropriate rows in table records are automatically deleted when a row in either foldersA or folderB is deleted? Or in this situation, am I forced to have to delete the rows in table "records" programatically? Thanks for you help!

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  • Creating C++ client app for some abstract windows server - how to manage TCP connection to server speed?

    - by Kabumbus
    So we have some server with some address port and ip. we are developing that server so we can implement on it what ever we need for help. What are standard/best practices for data transfer speed management between C++ windows client app and server (C++)? My main point is in how to get how much data can be uploaded/downloaded from/to client via his low speed network to my relatively super fast server. (I need it for set up of his live stream Audio/Video bit rate) My try on explaining number 3. We do not care how fast is our server. It is always faster than needed. We care about client tyring to stream out to our server his media. he streams encoded (via ffmpeg) live video data to our server. But he has say ADSL with 500kb/s of outgoing traffic. Also he uses some ICQ or what so ever so he has less than 500 kb/s per second. And he wants to stream live video! So we need to set up our ffmpeg to encode video with respect to the bit rate user can provide. We develop server side and client side. We need a way of finding out how much user can upload per second currently (so value can change dynamically over time)

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  • one two-directed tcp socket OR two one-directed? (linux, high volume, low latency)

    - by osgx
    Hello I need to send (interchange) a high volume of data periodically with the lowest possible latency between 2 machines. The network is rather fast (e.g. 1Gbit or even 2G+). Os is linux. Is it be faster with using 1 tcp socket (for send and recv) or with using 2 uni-directed tcp sockets? The test for this task is very like NetPIPE network benchmark - measure latency and bandwidth for sizes from 2^1 up to 2^13 bytes, each size sent and received 3 times at least (in teal task the number of sends is greater. both processes will be sending and receiving, like ping-pong maybe). The benefit of 2 uni-directed connections come from linux: http://lxr.linux.no/linux+v2.6.18/net/ipv4/tcp_input.c#L3847 3847/* 3848 * TCP receive function for the ESTABLISHED state. 3849 * 3850 * It is split into a fast path and a slow path. The fast path is 3851 * disabled when: ... 3859 * - Data is sent in both directions. Fast path only supports pure senders 3860 * or pure receivers (this means either the sequence number or the ack 3861 * value must stay constant) ... 3863 * 3864 * When these conditions are not satisfied it drops into a standard 3865 * receive procedure patterned after RFC793 to handle all cases. 3866 * The first three cases are guaranteed by proper pred_flags setting, 3867 * the rest is checked inline. Fast processing is turned on in 3868 * tcp_data_queue when everything is OK. All other conditions for disabling fast path is false. And only not-unidirected socket stops kernel from fastpath in receive

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  • Database structure for ecommerce site

    - by imanc
    Hey Guys, I have been tasked with designing an ecommerce solution. The aspect that is causing me the most problems is the database. Currently the site consists of 10+ country based shops each with their own database (all residing on the same mysql instance). For the new site I'd rather all these shop databases be merged into one database so that all tables (products, orders, customers etc.) have a shop_id field. From a programming perspective this seems to make the most sense as we won't have to manage data across multiple databases. Currently the entire site generates about 120k orders a year, but is experiencing fairly heavy growth and we need to design a solution that will scale. In 5 years there may be more than a million orders per year and a database that contains 5 years order history (archiving maybe a solution here). The question is - do we use a single database, or do we keep the database-per-shop structure? I am currently trying to find supporting evidence for either avenue. The company I am designing the solution for prefer the per-shop database structure because they believe it will allow the sites to scale. But my argument is that the shop's database probably won't get that busy over the next few years that they exceed the capacity of a mysql database and a "no expenses spared" hardware set-up. I am wondering if anyone has any advice either way? Does anyone have experience with websites / ecommerce sites that have tables containing millions of records? I know there is probably not a clear answer here, but at what stage do we have too many records or too large table files to have a fast loading site? Also, if anyone has any advice on sources of information - books, websites, etc. where I can do further research, it would be highly appreciated! Cheers, imanc

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  • How to order results based on number of search term matches?

    - by Travis
    I am using the following tables in mysql to describe records that can have multiple searchtags associated with them: TABLE records ID title desc TABLE searchTags ID name TABLE recordSearchTags recordID searchTagID To SELECT records based on arbitrary search input, I have a statement that looks sort of like this: SELECT recordID FROM recordSearchTags LEFT JOIN searchTags ON recordSearchTags.searchTagID = searchTags.ID WHERE searchTags.name LIKE CONCAT('%','$search1','%') OR searchTags.name LIKE CONCAT('%','$search2','%') OR searchTags.name LIKE CONCAT('%','$search3','%') OR searchTags.name LIKE CONCAT('%','$search4','%'); I'd like to ORDER this resultset, so that rows that match with more search terms are displayed in front of rows that match with fewer search terms. For example, if a row matches all 4 search terms, it will be top of the list. A row that matches only 2 search terms will be somewhere in the middle. And a row that matches just one search term will be at the end. Any suggestions on what is the best way to do this? Thanks!

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  • LDAP query using Python: always no result

    - by Grey
    I am trying to use python to query LDAP server, and it always returns me no result. and anyone help me find what wrong with my python code? it runs fine without excpetions, and it always has no result. i played around with the filter like "cn=partofmyname" but just no luck. thanks for help import ldap try: l = ldap.open("server") l.protocol_version = ldap.VERSION3 l.set_option(ldap.OPT_REFERRALS, 0) output =l.simple_bind("cn=username,cn=Users,dc=domian, dc=net",'password$R') print output except ldap.LDAPError, e: print e baseDN = "DC=rim,DC=net" searchScope = ldap.SCOPE_SUBTREE ## retrieve all attributes - again adjust to your needs - see documentation for more options retrieveAttributes = None Filter = "(&(objectClass=user)(sAMAccountName=myaccount))" try: ldap_result_id = l.search(baseDN, searchScope, Filter, retrieveAttributes) print ldap_result_id result_set = [] while 1: result_type, result_data = l.result(ldap_result_id, 0) if len(result_data) == 0: print 'no reslut' break else: for i in range(len(result_set)): for entry in result_set[i]: try: name = entry[1]['cn'][0] email = entry[1]['mail'][0] phone = entry[1]['telephonenumber'][0] desc = entry[1]['description'][0] count = count + 1 print "%d.\nName: %s\nDescription: %s\nE-mail: %s\nPhone: %s\n" %\ (count, name, desc, email, phone) except: pass ## here you don't have to append to a list ## you could do whatever you want with the individual entry #if result_type == ldap.RES_SEARCH_ENTRY: # result_set.append(result_data) # print result_set except ldap.LDAPError, e: print e l.unbind()

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  • Sturts DB query execution problem

    - by henderunal
    Hello, I am trying to insert a data to my db2 9.7 database from IBM RAD 7.5 using struts 1.3 But when i execute the query i got this errors [Pastebin link][1] Here is my code KayitBean kayit=(KayitBean)form; //String name = kayit.getName(); String name="endee"; DBConn hb = new DBConn(); Connection conn =hb.getConnection(); System.out.println("basarili"); //String sql = "SELECT * FROM ENDER.\"MEKANDENEME\""; String sql = "INSERT INTO ENDER.\"MEKANDENEME\" VALUES (\'endere\' ,\'bos\');"; System.out.println(sql); System.out.println("basarili2"); PreparedStatement ps = conn.prepareStatement(sql); System.out.println("basarili3"); ResultSet rs = ps.executeQuery(); // String ender=rs.getArray(1).toString(); System.out.println("basarili4"); // System.out.println(rs); conn.close(); I am receiving this after System.out.println("basarili3");" Please help me.

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  • PHP Show all data in column

    - by user342391
    I am trying to show all of the data in the 'status' column of my table but am having troubles. What am I doing wrong: <?php $query1 = "SELECT id, status FROM alerts WHERE customerid='".$_SESSION['customerid']."' ORDER BY id LIMIT $start, $limit "; $result = mysql_query($query1); while ($row = mysql_fetch_array($result)) { echo $row['status'] ; } ?>

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  • Which fieldtype is best for storing PRICE values?

    - by BerggreenDK
    Hi there I am wondering whats the best "price field" in MSSQL for a shoplike structure? Looking at this overview: http://www.teratrax.com/sql_guide/data_types/sql_server_data_types.html We have datatypes called money, smallmoney, then we have decimal/numeric and lastly float and real Name, memory/disk-usage and value ranges: Money: 8 bytes (values: -922,337,203,685,477.5808 to +922,337,203,685,477.5807) Smallmoney: 4 bytes (values: -214,748.3648 to +214,748.3647) Decimal: 9 [default, min. 5] bytes (values: -10^38 +1 to 10^38 -1 ) Float: 8 bytes (values: -1.79E+308 to 1.79E+308 ) Real: 4 bytes (values: -3.40E+38 to 3.40E+38 ) My question is: is it really wise to store pricevalues in those types? what about eg. INT? Int: 4 bytes (values: -2,147,483,648 to 2,147,483,647) Lets say a shop uses dollars, they have cents, but I dont see prices being $49.2142342 so the use of a lot of decimals showing cents seems waste of SQL bandwidth. Secondly, most shops wouldn't show any prices near 200.000.000 (not in normal webshops at least... unless someone is trying to sell me a famous tower in Paris) So why not go for an int? An int is fast, its only 4 bytes and you can easily make decimals, by saving values in cents instead of dollars and then divide when you present the values. The other approach would be to use smallmoney which is 4 bytes too, but this will require the math part of the CPU to do the calc, where as Int is integer power... on the downside you will need to divide every single outcome. Are there any "currency" related problems with regionalsettings when using smallmoney/money fields? what will these transfer too in C#/.NET ? Any pros/cons? Go for integer prices or smallmoney or some other? Whats does your experience tell?

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  • Are closures in javascript recompiled

    - by Discodancer
    Let's say we have this code (forget about prototypes for a moment): function A(){ var foo = 1; this.method = function(){ return foo; } } var a = new A(); is the inner function recompiled each time the function A is run? Or is it better (and why) to do it like this: function method = function(){ return this.foo; } function A(){ this.foo = 1; this.method = method; } var a = new A(); Or are the javascript engines smart enough not to create a new 'method' function every time? Specifically Google's v8 and node.js. Also, any general recommendations on when to use which technique are welcome. In my specific example, it really suits me to use the first example, but I know thath the outer function will be instantiated many times.

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  • What database field should this be?

    - by alex
    I have a table called "Event". A column has "duration"--which is...how long that event lasts. What database type should this be? Integer? (in seconds)? In the future, I will do statements such as: If now() > event.duration THEN don't display the event.

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  • JOIN two tables to show already purchased items

    - by Norbert
    I have a table where I keep all my templates: templates template_id template_name template_price These templates can be purchased by a registered user and then are inserted in the payments table: payments payment_id template_id user_id Is there a way to join these two tables and get not just a list of templates that have been purchased by a certain user, but all the templates? And then figure out from there which ones have already been purchased? I used this SELECT, but only the ones that the user bought showed up. I would like to have all the rows from templates, but empty in case the user_id doesn't match. SELECT * FROM templates LEFT JOIN payments ON templates.template_id = payments.template_id WHERE user_id = 2 GROUP BY templates.template_id

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  • List of divisors of an integer n (Haskell)

    - by Code-Guru
    I currently have the following function to get the divisors of an integer: -- All divisors of a number divisors :: Integer -> [Integer] divisors 1 = [1] divisors n = firstHalf ++ secondHalf where firstHalf = filter (divides n) (candidates n) secondHalf = filter (\d -> n `div` d /= d) (map (n `div`) (reverse firstHalf)) candidates n = takeWhile (\d -> d * d <= n) [1..n] I ended up adding the filter to secondHalf because a divisor was repeating when n is a square of a prime number. This seems like a very inefficient way to solve this problem. So I have two questions: How do I measure if this really is a bottle neck in my algorithm? And if it is, how do I go about finding a better way to avoid repetitions when n is a square of a prime?

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  • one two-directed tcp socket of two one-directed? (linux, high volume, low latency)

    - by osgx
    Hello I need to send (interchange) a high volume of data periodically with the lowest possible latency between 2 machines. The network is rather fast (e.g. 1Gbit or even 2G+). Os is linux. Is it be faster with using 1 tcp socket (for send and recv) or with using 2 uni-directed tcp sockets? The test for this task is very like NetPIPE network benchmark - measure latency and bandwidth for sizes from 2^1 up to 2^13 bytes, each size sent and received 3 times at least (in teal task the number of sends is greater. both processes will be sending and receiving, like ping-pong maybe). The benefit of 2 uni-directed connections come from linux: http://lxr.linux.no/linux+v2.6.18/net/ipv4/tcp_input.c#L3847 3847/* 3848 * TCP receive function for the ESTABLISHED state. 3849 * 3850 * It is split into a fast path and a slow path. The fast path is 3851 * disabled when: ... 3859 * - Data is sent in both directions. Fast path only supports pure senders 3860 * or pure receivers (this means either the sequence number or the ack 3861 * value must stay constant) ... 3863 * 3864 * When these conditions are not satisfied it drops into a standard 3865 * receive procedure patterned after RFC793 to handle all cases. 3866 * The first three cases are guaranteed by proper pred_flags setting, 3867 * the rest is checked inline. Fast processing is turned on in 3868 * tcp_data_queue when everything is OK. All other conditions for disabling fast path is false. And only not-unidirected socket stops kernel from fastpath in receive

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  • XSLT 1.0: restrict entries in a nodeset

    - by Mike
    Hi, Being relatively new to XSLT I have what I hope is a simple question. I have some flat XML files, which can be pretty big (eg. 7MB) that I need to make 'more hierarchical'. For example, the flat XML might look like this: <D0011> .... .... and it should end up looking like this: <D0011> .... .... I have a working XSLT for this, and it essentially gets a nodeset of all the b elements and then uses the 'following-sibling' axis to get a nodeset of the nodes following the current b node (ie. following-sibling::*[position() =$nodePos]). Then recursion is used to add the siblings into the result tree until another b element is found (I have parameterised it of course, to make it more generic). I also have a solution that just sends the position in the XML of the next b node and selects the nodes after that one after the other (using recursion) via a *[position() = $nodePos] selection. The problem is that the time to execute the transformation increases unacceptably with the size of the XML file. Looking into it with XML Spy it seems that it is the 'following-sibling' and 'position()=' that take the time in the two respective methods. What I really need is a way of restricting the number of nodes in the above selections, so fewer comparisons are performed: every time the position is tested, every node in the nodeset is tested to see if its position is the right one. Is there a way to do that ? Any other suggestions ? Thanks, Mike

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  • How to use group by for grouping varchar data.

    - by Shantanu Gupta
    I have a table that contains some data given below pk_map_id preferences ImmediateParent Department_Id -------------------- -------------------- -------------------- -------------------- 20 14 5 1 21 15 5 1 22 16 6 1 23 9 4 2 24 4 3 2 25 24 20 2 26 25 20 2 27 23 13 2 I want to group my records on behalf of department then immediate parent then preferences each seperated by ',' i.e. department Immediate Parent preferences 1 5,6 14,15,16 2 4,3,20,13 9,4,24,25,23 and this table also Immediate parent preferences 5 14,15 6 16 4 9 3 4 20 24,25 13 13 In actual scenario all these are my ids which are to be replaced by their string fields. I am using sql server 2k5

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