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  • Where is the bottleneck in this code?

    - by Mikhail
    I have the following tight loop that makes up the serial bottle neck of my code. Ideally I would parallelize the function that calls this but that is not possible. //n is about 60 for (int k = 0;k < n;k++) { double fone = z[k*n+i+1]; double fzer = z[k*n+i]; z[k*n+i+1]= s*fzer+c*fone; z[k*n+i] = c*fzer-s*fone; } Are there any optimizations that can be made such as vectorization or some evil inline that can help this code? I am looking into finding eigen solutions of tridiagonal matrices. http://www.cimat.mx/~posada/OptDoglegGraph/DocLogisticDogleg/projects/adjustedrecipes/tqli.cpp.html

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  • online CSS optimizer?

    - by Dand
    Is there an online CSS optimizer equivalent to Googles JavaScript Closure Optimizer. I've found plenty of CSS compressors online, but I'm looking for a CSS optimizer ... where it actually removes redundant/conflicting attributes

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  • prevent using functions before initialization, constructors-like in C

    - by Hernán Eche
    This is the way I get to prevent funA,funB,funC, etc.. for being used before init #define INIT_KEY 0xC0DE //any number except 0, is ok static int initialized=0; int Init() { //many init task initialized=INIT_KEY; } int funA() { if (initialized!=INIT_KEY) return 1 //.. } int funB() { if (initialized!=INIT_KEY) return 1 //.. } int funC() { if (initialized!=INIT_KEY) return 1 //.. } The problem with this approach is that if some of those function is called within a loop so "if (initialized!=INIT_KEY)" is called again, and again, although it's not necessary. It's a good example of why constructors are useful haha, If it were an object I would be sure that when was created initialization was called, but in C, I don't know how to do it. Any other ideas are welcome!

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  • django - order query set by postgres function

    - by thebiglife
    My initial question was here and was related to the postgres backend. http://stackoverflow.com/questions/2408965/postgres-subquery-ordering-by-subquery Now my problem has moved onwards to the Django ORM layer. I essentially want to order a query by a postgres function ('idx', taken from the above stackoverflow work) I've gone through trying to use model.objects.extra(order_by ) or simply order_by but I believe both of these need the order_by parameter to be an attribute or a field known to Django. I'm trying to think how to solve this without having to revert to using an entirely raw SQL query through a model manager.

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  • How to make Visual C++ 9 not emit code that is actually never called?

    - by sharptooth
    My native C++ COM component uses ATL. In DllRegisterServer() I call CComModule::RegisterServer(): STDAPI DllRegisterServer() { return _Module.RegisterServer(FALSE); // <<< notice FALSE here } FALSE is passed to indicate to not register the type library. ATL is available as sources, so I in fact compile the implementation of CComModule::RegisterServer(). Somewhere down the call stack there's an if statement: if( doRegisterTypeLibrary ) { //<< FALSE goes here // do some stuff, then call RegisterTypeLib() } The compiler sees all of the above code and so it can see that in fact the if condition is always false, yet when I inspect the linker progress messages I see that the reference to RegisterTypeLib() is still there, so the if statement is not eliminated. Can I make Visual C++ 9 perform better static analysis and actually see that some code is never called and not emit that code?

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  • Wordpress Custom Query

    - by InnateDev
    I have posts that use a custom field for start date and end date. Query_posts returns an array of posts that exist in the category I'm filtering. How do I query posts using this custom field that has date i.e. 03/11/2010 and not the full array. Pagination works on the full array so it returns all posts. I can use an if else to only show the posts newer that today, then pagination doesn't work. Would I have to build a custom mysql query?

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  • MySQL - How do I insert an additional where clause into this full-text search query

    - by Steven
    I want to add a WHERE clause to a full text search query (to limit to past 24 hours), but wherever I insert it I get Low Level Error. Is it possible to add the clause and if so, how? $query = "SELECT * WHERE story_time > time()-86400 AND MATCH (story_title) AGAINST ('".validate_input($_GET['q'])."' IN BOOLEAN MODE) AS Relevance FROM ".$config['db']['pre']."stories WHERE MATCH (story_title) AGAINST ('+".validate_input($_GET['q'])."' IN BOOLEAN MODE) HAVING Relevance > 0.2 ORDER BY Relevance DESC, story_time DESC LIMIT ".validate_input(($_GET['page']-1)*10).",10";

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  • Resize an image and maintain quality?

    - by JasonS
    Hi, I have a problem with resizing images. What happens is that if you upload a file larger than the stated parameters, the image is cropped, then saved at 100% quality. So if I upload a large jpeg which is 272Kb. The image is cropped by 100 odd pixels. The file size then goes up to 1.2Mb. We are saving images at a 100% quality. I assume that this is what is causing the problem. The image is exported from Photoshop at 30% quality which reduces the file size. Resaving the image at 100% quality creates the same image but I assume with a lot of redundant file data. Has anyone encountered this before? Does anyone have a solution? This is what we are using. $source_im = imagecreatefromjpeg ($file); $dest_im = imagecreatetruecolor ($newsize_x, $newsize_y); imagecopyresampled ( $dest_im, $source_im, 0, 0, $offset_x, $offset_y, $newsize_x, $newsize_y, $sourceWidth, $sourceHeight ); imagedestroy ($source_im); if ($greyscale) { $dest_im = $this->imageconvertgreyscale ($dest_im); } imagejpeg($dest_im, $save_to_file, $quality); break;

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  • sql query need a help.

    - by benjamin button
    If i have a table with two fields.customer id and order. let's say i have in total order ID 1,2,3,4 all the customer can have all the four orders.like below 1234 1 1234 2 1234 3 1234 4 3245 3 3245 4 5436 2 5436 4 you can see above that 3245 customer doesnt have order id 1 and 2. how could i print in the query output like 3245 1 3245 2 5436 1 5436 3 EDIT: i dont order table but i have list of order's like we can hard code it in the query(1,2,3,4) i dont have an orders table.

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  • Adding a Third Table to a Two-Table Join Query

    - by John
    Hello, The query below works just fine. It pulls fields from two MySQL tables, "comment" and "login". It does this for rows where "username" in the table "login" equals the variable "$profile." It also pulls fields for rows where "loginid" in the table "comment" equals the "loginid" that is also being pulled from "login." I would like to pull data from a third table called "submission," which has the following fields: submissionid loginid title url displayurl datesubmitted I would like to pull fields from rows in "submission" where "loginid" equals the "loginid" that is already being pulled from the other two tables, "login" and "comment." How can I do this? Thanks in advance, John Query: $sqlStrc = "SELECT l.username, l.loginid, c.loginid, c.commentid, c.submissionid, c.comment, c.datecommented FROM comment AS c INNER JOIN login AS l ON c.loginid = l.loginid WHERE l.username = '$profile' ORDER BY c.datecommented DESC LIMIT 10";

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  • PHP Increasing writing to page speed.

    - by Frederico
    I'm currently writing out xml and have done the following: header ("content-type: text/xml"); header ("content-length: ".strlen($xml)); $xml being the xml to be written out. I'm near about 1.8 megs of text (which I found via firebug), it seems as the writing is taking more time than the script to run.. is there a way to increase this write speed? Thank you in advance.

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  • MYSQL Query with 2 columns in Table A related to 1 column in Table B

    - by CYREX
    I have 2 Tables, User and Mail. In User Table i have 2 columns that i will use, the ID column which makes the relation with the Mail Table and it is the Index of User Table and the Name column. In Mail Table i have Receiver Column and Sender Column. Both columns, Receiver and Sender have a number that relates to the ID Column in the User Table. In the User Table is where the name columns resides and i want to make a query that shows me the Receiver and Sender Columns but with the name of the user, not the ID. Up to this point i have this: SELECT name AS Send, name AS Receive FROM mail,user WHERE sender=guid; I know there is still a part of the query missing but i can not figure out what else to put to tell it to show in the SEND output column the name of the sender and in the RECEIVE output column the name of the receiver.

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  • Cleaner way of using modulus for columns

    - by WmasterJ
    I currently have a list (<ul>) of people that I have divided up into two columns. But after finishing the code for it I keept wondering if there is a more effective or clean way to do the same thing. echo "<table class='area_list'><tr>"; // Loop users within areas, divided up in 2 columns $count = count($areaArray); for($i=0 ; $i<$count ; $i++) { $uid = $areaArray[$i]; // get the modulus value + ceil for uneven numbers $rowCalc = ($i+1) % ceil($count/2); if ($rowCalc == 1) echo "<td><ul>"; // OUTPUT the actual list item echo "<li>{$users[$uid]->profile_lastname}</li>"; if ($rowCalc == 0 && $i!=0) echo "</ul></td>"; } echo "</tr></table>"; Any ideas of how to make this cleaner or do it in another way?

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  • SQL Not Exists in this Query - is it possible

    - by jason barry
    This is my script - it simply looks for the image file associated to a person record. Now the error will display if there is NO .jpg evident when the query runs. Msg 4860, Level 16, State 1, Line 1 Cannot bulk load. The file "C:\Dev\ClientServices\Defence\RAN\Shore\Config\Photos\002054.2009469432270600.001.jpg" does not exist. Is there a way to write this query to 'IF not exists then set id_number = '002054.2009469432270427.001' - so it wil always display this photo for any records without a picture. ALTER procedure [dbo].[as_ngn_sp_REP_PH108_photo] (@PMKEYS nvarchar(50)) AS ---exec [as_ngn_sp_REP_PH108_photo] '8550733' SET NOCOUNT ON DECLARE @PATH AS NVARCHAR(255) DECLARE @ID_NUMBER NVARCHAR(27) DECLARE @SQL AS NVARCHAR(MAX) EXEC DB_GET_DB_SETTING'STAFF PICTURE FILE LOCATION', 0, @PATH OUTPUT IF RIGHT(@PATH,1) <> '\' SET @PATH = @PATH + '\' SELECT @ID_NUMBER = ID_NUMBER FROM aView_person WHERE EXTRA_CODE_1 = @PMKEYS SET @PATH = @PATH + @ID_NUMBER + '.jpg' SET @SQL = 'SELECT ''Picture1'' [Picture], BulkColumn FROM OPENROWSET(Bulk ''' + REPLACE(@PATH,'''','''''') + ''', SINGLE_BLOB) AS RAN' EXEC SP_EXECUTESQL @SQL

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  • Does anybody have any suggestions on which of these two approaches is better for large delete?

    - by RPS
    Approach #1: DECLARE @count int SET @count = 2000 DECLARE @rowcount int SET @rowcount = @count WHILE @rowcount = @count BEGIN DELETE TOP (@count) FROM ProductOrderInfo WHERE ProductId = @product_id AND bCopied = 1 AND FileNameCRC = @localNameCrc SELECT @rowcount = @@ROWCOUNT WAITFOR DELAY '000:00:00.400' Approach #2: DECLARE @count int SET @count = 2000 DECLARE @rowcount int SET @rowcount = @count WHILE @rowcount = @count BEGIN DELETE FROM ProductOrderInfo WHERE ProductId = @product_id AND FileNameCRC IN ( SELECT TOP(@count) FileNameCRC FROM ProductOrderInfo WITH (NOLOCK) WHERE bCopied = 1 AND FileNameCRC = @localNameCrc ) SELECT @rowcount = @@ROWCOUNT WAITFOR DELAY '000:00:00.400' END

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  • Need help optimizing MYSQL query with join

    - by makeee
    I'm doing a join between the "favorites" table (3 million rows) the "items" table (600k rows). The query is taking anywhere from .3 seconds to 2 seconds, and I'm hoping I can optimize it some. Favorites.faver_profile_id and Items.id are indexed. Instead of using the faver_profile_id index I created a new index on (faver_profile_id,id), which eliminated the filesort needed when sorting by id. Unfortunately this index doesn't help at all and I'll probably remove it (yay, 3 more hours of downtime to drop the index..) Any ideas on how I can optimize this query? In case it helps: Favorite.removed and Item.removed are "0" 98% of the time. Favorite.collection_id is NULL about 80% of the time. SELECT `Item`.`id`, `Item`.`source_image`, `Item`.`cached_image`, `Item`.`source_title`, `Item`.`source_url`, `Item`.`width`, `Item`.`height`, `Item`.`fave_count`, `Item`.`created` FROM `favorites` AS `Favorite` LEFT JOIN `items` AS `Item` ON (`Item`.`removed` = 0 AND `Favorite`.`notice_id` = `Item`.`id`) WHERE ((`faver_profile_id` = 1) AND (`collection_id` IS NULL) AND (`Favorite`.`removed` = 0) AND (`Item`.`removed` = '0')) ORDER BY `Favorite`.`id` desc LIMIT 50;

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  • DataTable linq query iteration

    - by Ravi
    Hi, I want to Enumerate Linq Query. Below i specified example. EX: DataTable _slidingDataTable = new DataTable("test"); for(int i=0; i<5;i++) { DataRow row = _slidingDataTable.NewRow(); startPosition = DateTime.Now; for(int i=0; i<5;i++) { _slidingDataTable.Columns.Add("TransferTime"); row[columnName] = startPosition ; _slidingDataTable.Columns.Add("TransferData"); row[columnName] = "Test"+i; } _slidingDataTable.Rows.Add(row); } var query1 = from myRow in _slidingDataTable.AsEnumerable() where myRow.Field<DateTime>("TransferTime") == startPosition select myRow; This query output should be collection of rows. How to get collection row & iterate.

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  • How to optimize a postgreSQL server for a "write once, read many"-type infrastructure ?

    - by mhu
    Greetings, I am working on a piece of software that logs entries (and related tagging) in a PostgreSQL database for storage and retrieval. We never update any data once it has been inserted; we might remove it when the entry gets too old, but this is done at most once a day. Stored entries can be retrieved by users. The insertion of new entries can happen rather fast and regularly, thus the database will commonly hold several millions elements. The tables used are pretty simple : one table for ids, raw content and insertion date; and one table storing tags and their values associated to an id. User search mostly concern tags values, so SELECTs usually consist of JOIN queries on ids on the two tables. To sum it up : 2 tables Lots of INSERT no UPDATE some DELETE, once a day at most some user-generated SELECT with JOIN huge data set What would an optimal server configuration (software and hardware, I assume for example that RAID10 could help) be for my PostgreSQL server, given these requirements ? By optimal, I mean one that allows SELECT queries taking a reasonably little amount of time. I can provide more information about the current setup (like tables, indexes ...) if needed.

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  • optimized grid for rectangular items

    - by peterchen
    I have N rectangular items with an aspect ratio Aitem (X:Y). I have a rectangular display area with an aspect ratio Aview The items should be arranged in a table-like layout (i.e. r rows, c columns). what is the ideal grid rows x columns, so that individual items are largest? (rows * colums = N, of course - i.e. there may be "unused" grid places). A simple algorithm could iterate over rows = 1..N, calculate the required number of columns, and keep the row/column pair with the largest items. I wonder if there's a non-iterative algorithm, though (e.g. for Aitem = Aview = 1, rows / cols can be approximated by sqrt(N)).

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  • Nginx , Apache , Mysql , Memcache with server 4G ram. How optimize to enoigh of memory?

    - by TomSawyer
    i have 1 dedicated server with Nginx proxy for Apache. Memcache, mysql, 4G Ram. These day, my visitor on my site wasn't increased, but my server get overload always in some specified time. (9AM - 15PM) Ram in use is increased second by second to full. that's moment, my server will get overload. i have to kill all apache , mysql service and reboot it to get free memory. and it'll full again. that's the terrible circle. here is my ram in use at the moment 160(nginx) 220(apache) 512(memcache) 924(mysql) here's process number 4(nginx) 14(apache) 5(memcache) 20(mysql) and here's my my.cnf config. someone can help me to optimize it? [mysqld] datadir=/var/lib/mysql socket=/var/lib/mysql/mysql.sock user=mysql skip-locking skip-networking skip-name-resolve # enable log-slow-queries log-slow-queries = /var/log/mysql-slow-queries.log long_query_time=3 max_connections=200 wait_timeout=64 connect_timeout = 10 interactive_timeout = 25 thread_stack = 512K max_allowed_packet=16M table_cache=1500 read_buffer_size=4M join_buffer_size=4M sort_buffer_size=4M read_rnd_buffer_size = 4M max_heap_table_size=256M tmp_table_size=256M thread_cache=256 query_cache_type=1 query_cache_limit=4M query_cache_size=16M thread_concurrency=8 myisam_sort_buffer_size=128M # Disabling symbolic-links is recommended to prevent assorted security risks symbolic-links=0 [mysqldump] quick max_allowed_packet=16M [mysql] no-auto-rehash [isamchk] key_buffer=256M sort_buffer=256M read_buffer=64M write_buffer=64M [myisamchk] key_buffer=256M sort_buffer=256M read_buffer=64M write_buffer=64M [mysqlhotcopy] interactive-timeout [mysql.server] user=mysql basedir=/var/lib [mysqld_safe] log-error=/var/log/mysqld.log pid-file=/var/run/mysqld/mysqld.pid

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