# Daily Archives

• ### What is the best way to find the period of a (repeating) list in Mathematica?

##### - by Arnoud Buzing
What is the best way to find the period in a repeating list? For example: a = {4, 5, 1, 2, 3, 4, 5, 1, 2, 3, 4, 5, 1, 2} has repeat {4, 5, 1, 2, 3} with the remainder {4, 5, 1, 2} matching, but being incomplete. The algorithm should be fast enough to handle longer cases, like so: b = RandomInteger[10000, {100}]; a = Join[b, b, b, b, Take[b, 27]] The algorithm should return \$Failed if there is no repeating pattern like above.

• ### Drawing bezier curve with limited subdivisions in OpenGL

##### - by xEnOn
Is it possible to tell OpenGL to draw a 4 degree (5 control points) bezier curve with 10 subdivisions? I was trying with this: point ctrlpts[] = {..., ..., ..., ...}; glMap1f(GL_MAP1_VERTEX_3, 0, 1, 3, 5, ctrlpts); glBegin(GL_LINE_STRIP); for (i = 0; i <= 30; i++) glEvalCoord1f((GLfloat) i/30.0); glEnd(); But this just draws the curve nicely. I am thinking that I want the algorithm inside the bezier curve to draw only until 10 subdivisions and then stop. The line should look a little facet.

• ### Dealing with sequences in OpenCV?

I have 2 sequences. One (lets call this cvSeq x), which contains a number of contours (derived from cvFindContours) and a second (lets call this cvSeq y) which I have used cvCreateSeq upon, but doesn't actually have anything in it. I am looping through all the contours in x, and if a contour meets specific criteria, I add it to y. I am able to do the looping, but I don't know how to add an contour in x to y if it meets the criteria. Does anyone know how to add a contour in a sequence to another sequence (that is empty)? Code examples will be appreciated. PS: cvStartFindContours is not an option.

• ### Learning Hibernate: too many connections

##### - by stivlo
I'm trying to learn Hibernate and I wrote the simplest Person Entity and I was trying to insert 2000 of them. I know I'm using deprecated methods, I will try to figure out what are the new ones later. First, here is the class Person: @Entity public class Person { private int id; private String name; @Id @GeneratedValue(strategy = GenerationType.TABLE, generator = "person") @TableGenerator(name = "person", table = "sequences", allocationSize = 1) public int getId() { return id; } public void setId(int id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } } Then I wrote a small App class that insert 2000 entities with a loop: public class App { private static AnnotationConfiguration config; public static void insertPerson() { SessionFactory factory = config.buildSessionFactory(); Session session = factory.getCurrentSession(); session.beginTransaction(); Person aPerson = new Person(); aPerson.setName("John"); session.save(aPerson); session.getTransaction().commit(); } public static void main(String[] args) { config = new AnnotationConfiguration(); config.addAnnotatedClass(Person.class); config.configure("hibernate.cfg.xml"); //is the default already new SchemaExport(config).create(true, true); //print and execute for (int i = 0; i < 2000; i++) { insertPerson(); } } } What I get after a while is: Exception in thread "main" org.hibernate.exception.JDBCConnectionException: Cannot open connection Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Too many connections Now I know that probably if I put the transaction outside the loop it would work, but mine was a test to see what happens when executing multiple transactions. And since there is only one open at each time, it should work. I tried to add session.close() after the commit, but I got Exception in thread "main" org.hibernate.SessionException: Session was already closed So how to solve the problem?

• ### Excluding directories in Exuberant CTags

##### - by DeepYellow
I'm working with a very large code base and I find it useful to be selective about which directories are included for use with Exuberant Ctags. The --exclude option works well to eliminate individual file and directory names (with globing wildcards), but I can't figure out how to get it to exclude path patterns containing more than one directory. For example, I may want to exclude a directory tests, but only when processing thirdparty\tests (under Windows). The problem is if I just use --exclude=tests I exclude too many directories, including a test directory in the code I'm actively working on. Here are some things I've tried: --exclude=thirdparty\tests --exclude=thirdparty\\tests --exclude=*\thirdparty\tests --exclude=*\\thirdparty\\tests --exclude=thirdparty/tests Ctags silently ignores all these as evidenced by an examination of the tags file. How can I exclude a directory only when it is preceded by a given parent directory?

• ### initializer_list and move semantics

##### - by FredOverflow
Am I allowed to move elements out of a std::initializer_list<T>? #include <initializer_list> #include <utility> template<typename T> void foo(std::initializer_list<T> list) { for (auto it = list.begin(); it != list.end(); ++it) { bar(std::move(*it)); // kosher? } } Since std::intializer_list<T> requires special compiler attention and does not have value semantics like normal containers of the C++ standard library, I'd rather be safe than sorry and ask.

• ### Bings Search API always returns the same 10 results

##### - by Dofs
I am trying to figure Bings Seach API out. I have added the SOAP service to my solution, and I do receive results. The issue, is that the displayed results are always the same, not matter what I have set the request.Web to. When I do the search, it displays 98 results, so it isn't the lack of results. BingService soapClient = new BingService(); string resp = string.Empty; SearchRequest request = new SearchRequest(); request.AppId = ConfigurationManager.AppSettings["BingKey"]; request.Sources = new BingLiveSearchService.SourceType[] { SourceType.Web }; request.Query = query; request.Web = new BingLiveSearchService.WebRequest { Count = 10, Offset = 10 }; var response = soapClient.Search(request); if (response.Web != null && response.Web.Total > 0) { resp += "TOTAL COUNT:"+response.Web.Total +"<br/><br />"; foreach (var item in response.Web.Results) { resp += "<div style='padding-bottom:10px;'>" + item.Title + "</div>"; } }

• ### C# SortedList, getting value by key

##### - by user1004039
I have SortedList in descending order. public class MyComparer : IComparer<int> { public int Compare(int x, int y) { if (x.CompareTo(y) > 0) return -1; return 1; } } class Program { static void Main(string[] args) { SortedList<int, bool> myList = new SortedList<int, bool>(new MyComparer()); myList.Add(10, true); bool check = myList[10];//In this place an exception "Can't find key" occurs } } When SortedList created without my own IComparer the code works fine and no exception occurs.

• ### Keymap issues with NX from Mac OS X Lion

##### - by Andy
I tried to answer the question from Mark: Keymap issues with NX from Mac OS X Lion to Ubuntu However, it is locked so I figured I would post a new question / answer. I have been trying to answer this for a few days now because I have no issues when connecting through NX Client (technically OpenNX) to FreeNX server from an iMac (with Lion), but if I try to connect with a Macbook Pro I get horrible keyboard binding issues. The fix that is working for me is to go into: ~/.nx/config/HOST.nxs and change: <option key="Current keyboard" value="false"/> <option key="Custom keyboard layout" value="empty"/> <option key="Grab keyboard" value="false"/> I have tried this on three NX Servers and all are fixed. Hope it helps or gets you closer. Always check in the ~/.nx/temp/ for the sshlog and see if --keyboard="empty/empty" instead of "pc105/en" because the Mac is really pc104. 9:05:35: startsession --session="HOST" --type="unix-gnome" --cache="8M" --images="32M" --link="adsl" --geometry="2556\ x1396" --screeninfo="2560x1440x32+render" --keyboard="empty/empty" --backingstore="1" --encryption="1" --composite="1" --\ shmem="1" --shpix="1" --streaming="1" --samba="0" --cups="0" --nodelay="1" --defer="0" --client="macosx" --media="0" --st\ rict="0" --aux="1"

• ### "Error: Unknown error" when trying to start virtual machine from VMware server

##### - by slhck
Problem We are running VMware Server 2.0.0 build-116503 on a Ubuntu 10.04 LTS server. There is a virtual machine installed, running Lotus Domino on Windows Server 2003. Ever since a sudden power failure last week, the virtual machine won't properly start up. When I run the command: vmrun -T server -h https://127.0.0.1:8333/sdk -u root -p jk2x2208 start "[standard] lotus/test.vmx" … after 30 seconds it displays: Error: Unknown error That's about everything I get. I know the command is right, since that's what we've used all the time. This has happened last Saturday after a scheduled backup shutdown, and somehow I was able to start it again. This week, it happened again, and I can't get it back up. Occasionally, I also get: Error: Cannot connect to the virtual machine When I get this, and I run the start command, it seemingly works. Why is this so random? Which configuration could have been messed up? What I've tried / other info I already shut down VMware itself with /etc/init.d/vmware stop. This works. I tried to start VMware again with /etc/init.d/vmware start. It complains that it's "not configured", which is why I had to rm /etc/vmware/not_configured, and then try to start again. There have been no software updates on the machine, and no configuration changes

• ### Changing User/Group to allow PHP to chmod/rename and move_upload_file()

##### - by moe
It seems like I cannot do anything with my PHP script on my VPS. It returns 'Permission denied' when I try to upload something to a directory. Yes, I have changed the permission to 777, and it works, but I do not like the insecurity When running the command: ps axu|grep apache|grep -v grep It returns nobody 7689 0.1 3.8 50604 20036 ? S 21:38 0:00 /usr/local/apache/bin/httpd -k start -DSSL root 13600 0.0 3.8 50304 20348 ? Ss Jun06 0:46 /usr/local/apache/bin/httpd -k start -DSSL nobody 15733 0.1 3.8 50700 20156 ? S 21:39 0:00 /usr/local/apache/bin/httpd -k start -DSSL nobody 15818 0.1 3.8 51492 20180 ? S 21:39 0:00 /usr/local/apache/bin/httpd -k start -DSSL nobody 23843 0.1 3.7 51336 19592 ? S 21:40 0:00 /usr/local/apache/bin/httpd -k start -DSSL nobody 30335 0.0 3.5 50436 18496 ? S 21:41 0:00 /usr/local/apache/bin/httpd -k start -DSSL nobody 30406 0.0 3.5 50444 18544 ? S 21:41 0:00 /usr/local/apache/bin/httpd -k start -DSSL nobody 30407 0.0 3.5 50556 18696 ? S 21:41 0:00 /usr/local/apache/bin/httpd -k start -DSSL nobody 30472 0.0 3.6 50828 19348 ? S 21:41 0:00 /usr/local/apache/bin/httpd -k start -DSSL nobody 30474 0.0 3.5 50668 18868 ? S 21:41 0:00 /usr/local/apache/bin/httpd -k start -DSSL nobody 30476 0.0 3.6 50532 19064 ? S 21:41 0:00 /usr/local/apache/bin/httpd -k start -DSSL nobody 30501 0.0 3.8 50556 20080 ? S 21:36 0:00 /usr/local/apache/bin/httpd -k start -DSSL nobody 32341 0.0 3.5 50444 18492 ? S 21:41 0:00 /usr/local/apache/bin/httpd -k start -DSSL nobody 32370 0.0 3.5 50444 18476 ? S 21:42 0:00 /usr/local/apache/bin/httpd -k start -DSSL nobody 32414 0.1 3.7 51336 19524 ? S 21:42 0:00 /usr/local/apache/bin/httpd -k start -DSSL nobody 32416 0.1 3.5 50668 18816 ? S 21:42 0:00 /usr/local/apache/bin/httpd -k start -DSSL nobody 32457 0.1 3.6 50828 19320 ? S 21:42 0:00 /usr/local/apache/bin/httpd -k start -DSSL nobody 32458 0.1 3.6 50772 19276 ? S 21:42 0:00 /usr/local/apache/bin/httpd -k start -DSSL nobody 32459 0.0 3.5 50444 18504 ? S 21:42 0:00 /usr/local/apache/bin/httpd -k start -DSSL nobody 32460 0.2 3.6 50828 19320 ? S 21:42 0:00 /usr/local/apache/bin/httpd -k start -DSSL nobody 32463 0.0 3.5 50444 18472 ? S 21:42 0:00 /usr/local/apache/bin/httpd -k start -DSSL nobody 32466 0.0 3.4 50436 17960 ? S 21:42 0:00 /usr/local/apache/bin/httpd -k start -DSSL The owner of the directory is 'user [505]' and the group is 'user[508]' (as seen in WinSCP) What can I do to change the Apache Handler to the right owner and group to allow my PHP scripts to work? P.S My PHP is not set to safe mode, and the open_basedir is set to no value EDIT: This is what my httpd.conf looks like (for the associative domain) <VirtualHost *:80> ServerName domain.com ServerAlias www.domain.com DocumentRoot /home/domain/public_html ServerAdmin [email protected] ## User <theUsername> # Needed for Cpanel::ApacheConf <IfModule mod_userdir.c> Userdir disabled Userdir enabled <userName> </IfModule> <IfModule mod_suphp.c> suPHP_UserGroup <userName> <userName> </IfModule> <IfModule !mod_disable_suexec.c> SuexecUserGroup <userName> <userName> </IfModule> CustomLog /usr/local/apache/domlogs/domain.com-bytes_log "%{%s}t %I .\n%{%s}t %O ." CustomLog /usr/local/apache/domlogs/domain.com combined ScriptAlias /cgi-bin/ /home/domain/public_html/cgi-bin/ #Options -ExecCGI -Includes #RemoveHandler cgi-script .cgi .pl .plx .ppl .perl

• ### verisign certificate into jboss server SSL

##### - by rfders
i'm trying to enable jboss to uses ssl protocol using a previously generated certificate from verisign, i imported both certificate, server certificate and ca certificate into the keytore file, and i configured the server.xml to use that keystore and activate ssl protocol, then when i run the jboss, I got this error "certificate or key corresponds to the SSL cipher suites which are enabled" Question, reading some post on internet, i found that every example was made it generating a Certificate Request, it stricly necesary to do that if i already have the server certificate and that CSR has to be imported into the keystore as well ? at this point i'm very confused about this issue, i tried almost every solutions posted in several forums but till now i haven't any luck !! can you give me some tips in order to solve this problem. thanks in advance this are my keystore file: Keystore type: jks Keystore provider: SUN Your keystore contains 2 entries j2ee, Dec 29, 2009, trustedCertEntry, Certificate fingerprint (MD5): 69:CC:2D:2A:2D:EF:C4:DB:A2:26:35:57:06:29:7D:4C ugent, Dec 29, 2009, trustedCertEntry, Certificate fingerprint (MD5): AC:D8:0E:A2:7B:B7:2C:E7:00:DC:22:72:4A:5F:1E:92 and my server.xml configuration:

• ### how to customize debian installation cd for your needs

##### - by Frank
I have with me a Debian CD, which I want to customize for my own needs. I have extracted the CD and started to change some parts of it, e.g Splash screen (splash.png) installer Title (through isolinux.cfg) etc These are the things that I want to do: Change the Splash logo at start up of installation to have my own (which is done) Change the grub boot parameters to use my comapny name on it. Change the set of packages in it, so that I can have my own set of packages in it and only those packages are installed Do some post installation steps Customize it's startup and login screen to have my company name. After I am done with this customization, I need to build its live installer CD so that I can install it on my own, on any other system.

• ### Asus P6X58-E WS motherboard memory limits

##### - by Arsen Zahray
I've just ordered motherboard Asus P6X58-E WS, and now I'm, looking for memory for it. It has 6 slots, but the strange thing is, that in specifications it says that it is limited to 24G of memory . I'm planning on using 8G Kingston KVR1333D3D4R9S/8G sticks with it. Using those sticks, I'll be teoretically limited to 48G. Does the 24G limitation mean, that even if I install all 6 sticks, I still will be limited by 24G of possible memory? Sorry if the question seems dumb, but I never faced such a limitation before

• ### IE9 apprears to be ignoring RewriteRule in htaccess file

##### - by mouli
I have a site that uses SEF URLs and htaccess RewriteRules to serve up the pages. This has worked fine for several years until the arrival of IE9. Now it appears that the links are not being rewritten and the site is dead in the water. I have tried different compatabilty modes, to no avail, and I've played with the Rewrite Rules over and over, tried different doctypes and a few other browser settings. I agree that it cannot in theory be a browser specific problem if the problem is with the htaccess file but this site works in IE8, firefox and chrome. I have run the rewriterule through a validator and it looks fine. Any ideas would be appreciated as I am running out of ideas. The site is www.marlboroughsounds.co.nz a sample link is http://www.marlboroughsounds.co.nz/walking/freedom-walk-queen-charlotte-track/4dfw and the rewrite rule thats not working looks like this: RewriteRule ^walking/.*/([a-z0-9_]*)/?\$ /walking.php?act_code=\$1 [L] The link fails and it serves up a browser 404 page, not even the custom 404 I have for the site. Any ideas would be much appreciated as I am stumped.

• ### Why is my filesystem being mounted read-only in linux?

##### - by Tim
I am trying to set up a small linux system based on Gentoo on a VirtualBox machine, as a step towards deploying the same system onto a low-spec Single Board Computer. For some reason, my filesystem is being mounted read-only. In my /etc/fstab, I have: /dev/sda1 / ext3 defaults 0 0 none /proc proc defaults 0 0 none /sys sysfs defaults 0 0 none /dev/shm tmpfs defaults 0 0 However, once booted /proc/mounts shows rootfs / rootfs rw 0 0 /dev/root / ext3 ro,relatime,errors=continue,barrier=0,data=writeback 0 0 proc /proc proc rw,nosuid,nodev,noexec,relatime 0 0 sysfs /sys sysfs rw,nosuid,nodev,noexec,relatime 0 0 udev /dev tmpfs rw,nosuid,relatime,size=10240k,mode=755 0 0 devpts /dev/pts devpts rw,nosuid,noexec,relatime,gid=5,mode=620 0 0 none /dev/shm tmpfs rw,relatime 0 0 usbfs /proc/bus/usb usbfs rw,nosuid,noexec,relatime,devgid=85,devmode=664 0 0 binfmt_misc /proc/sys/fs/binfmt_misc binfmt_misc rw,nosuid,nodev,noexec,relatime 0 0 (the above may contain errors: there's no practical way to copy and paste) The partition at /dev/hda1 is clearly being mounted OK, since I can read all the data, but it's not being mounted as described in fstab. How might I go about diagnosing / resolving this? Edit: I can remount with mount -o remount,rw / and it works as expected, except that /proc/mounts reports /dev/root mounted at / rather than /dev/sda1 as I'd expect. If I try to remount with mount -a I get mount: none already mounted or /sys busy mount: according to mtab, sysfs is already mounted on /sys Edit 2: I resolved the problem with mount -a (the same error was occuring during startup, it turned out) by changing the sysfs and proc lines to proc /proc proc [...] sysfs /sys sysfs [...] Now mount -a doesn't complain, but it doesn't result in a read-write root partition. mount -o remount / does cause the root partition to be remounted, however.

• ### Symmetrix gatekeepers on Solaris 10

##### - by Milner
I have some Solaris machines that are connected to EMC Symmetrix for SAN storage. Apparently the Symm has a gatekeeper device that is used with the symmetrix CLI. We don't need the CLI, but I have these gatekeeper devices that constantly fill /var/adm/messages and the like with corrupt label errors. Is there anything I can do (short of deleting the devices on machine start) to get rid of them? Or should I just try to get our SAN guy to get the installer for the CLI? These things are getting annoying, and the devfsadmd daemon keeps rediscovering them on boot.

• ### Insufficient channel capacity of 1GBit

##### - by Roman S
There is a Caching Server (Varnish): it receives data from Amazon S3 on request, saves it for some time and gives it to the client. We have encountered the problem of insufficient channel capacity of 1GBit. Peak load within 4 hours completely chokes the channel. Server performance is sufficient for now. Approximately 4.5TB of data are transmitted per day. More than 100TB are accumulated per month. The first thought that comes to mind is simply to add one more 1GBit port and sleep peacefully until 2GBit are not enough (it may happen quite quickly) or one server is not able to handle it. And then we just need to add new Caching Servers. But now we need a Load Balancer, which will send requests on one and the same URL, always on one and the same server (to avoid multiple copies of the same cached objects). Here are the questions: Does a Balancer need a band equal to sum of all bands of Caching Servers? What shall we do in case there are no ports in a Balancer? Should we add more Balancers or solve the problem by means of Round robin DNS? What are the standard approaches to such problems? Can anyone advise hosting-companies, which can solve this problem? We are interested in American and European markets.

• ### Routing for IPSec tunnel

##### - by Emre A
For Juniper NetScreen-NS25, I configured a site-to-site IPSec tunnnel. For the outside interface of remote site, I also needed to go through tunnel which has the same IP as IPSec gateway. Now, when I add static route to route that outside interface IP through tunnel while tunnel is up, there would be no problem at all but if the tunnel is down for some reason, it cannot be re-established as the routing for the IPSec gateway IP which is the same as outside interface IP is set to go through tunnel which it needed to re-etablish at that time. So, packets won't hit that IP. I tried adding another routing entry which has metric 2 through other gateway but it did'nt succeeded. So, what type of routing should I configure to reach that IP when tunnel is down. Thanks in advance.

• ### Decreasing Root Disk Size of an "EBS Boot" AMI on EC2

##### - by darkAsPitch
So I have followed Eric's wonderful article here: http://alestic.com/2009/12/ec2-ebs-boot-resize This was the code basically that helped me increase the default size of the AMI: ec2-run-sintances ami-ID -n 1 --key keypair.pem --block-device-mapping "/dev/sda1=:250" Running Ubuntu 11.10 I didn't even have to re-size the disk afterwards, it was immediately a 250GB drive. How do I go about decreasing the default size of the AMI??? I tried: ec2-run-sintances ami-ID -n 1 --key keypair.pem --block-device-mapping "/dev/sda1=:100" Obviously... but I was told: Client.InvalidBlockDeviceMapping: Volume of size 100GB is smaller than snapshot ####### <250

• ### Dell Windows 7 DVD includes IE9, where to find IE8?

##### - by mjmcinto
It appears as though we can now only get a 64 bit installation of windows 7 to come with IE9, and I cannot find an installer for IE 8 for it. This presents a problem, as I am building a new machine for a developer, but the company does not support IE9 yet, and all development needs to be able to be run on IE8. I would rather have them on a 64 bit version of windows so they can have more than 4GB of RAM (can get IE8 on 32 bit win 7). Does anyone know how to get IE 8 on a new 64 bit version of win 7?