Search Results

Search found 6992 results on 280 pages for 'engineered systems'.

Page 77/280 | < Previous Page | 73 74 75 76 77 78 79 80 81 82 83 84  | Next Page >

• What is a good programming language for AI?

  - by Mark

  Besides Lisp and Prolog what is a good programming language for programming intelligent systems?

  Read the article

• Why do companies use Source Safe?

  - by Nate

  Why do you (and/or your company) use Visual Source Safe instead of the "other" version control systems?

  Read the article

• How to filter/sort/rank object model nodes?

  - by BCS

  I have some kind of object model and I need to filter and sort it's nodes for some kind of property. What kinds of automated systems exist to generate and select properties of the object model that correlate to what I want? (I'm intentionally being abstract and non-specific) I'm thinking of a system that works kind of like spam filters or supervised classification systems in that given an example data set it identifies rules that find nodes of interest. However I'm looking for a more general system in that it shouldn't require any design time information about the object model. It should work equality well as a spam filter on e-mail, a bug finder on a code base, an interest filter in a newsgroup or bot accounts finder on a social networking site. As long as it can explore the object model via reflection and be given a set of "interesting" nodes, it should be able to find rules that will find more nodes like them.

  Read the article

• How to identify/handle text file newlines in Java?

  - by rafrafUk

  Hi Everyone! I get files in different formats coming from different systems that I need to import into our database. Part of the import process it to check the line length to make sure the format is correct. We seem to be having issues with files coming from UNIX systems where one character is added. I suspect this is due to the return carriage being encoded differently on UNIX and windows platform. Is there a way to detect on which file system a file was created, other than checking the last character on the line? Or maybe a way of reading the files as text and not binary which I suspect is the issue? Thanks Guys !

  Read the article

• question about Littles Law

  - by davit-datuashvili

  I know that Little's Law states (paraphrased): the average number of things in a system is the product of the average rate at which things leave the system and the average time each one spends in the system, or: n=x*(r+z); x-throughput r-response time z-think time r+z - average response time now i have question about a problem from programming pearls: Suppose that system makes 100 disk accesses to process a transaction (although some systems require fewer, some systems will require several hundred disk access per transaction). How many transactions per hour per disk can the system handle? please help

  Read the article

• JQuery or Javascript solution for selecting default value in drop down

  - by user1446843

  I have a calender list in a webpart page, this webpart page has a version number in it's title e.g. "WebPart 1.62". What I need to do is when a New item is created in the calender list on a webpart page, the New Item form has a dropdown menu 'SystemID' which gets it's values from the title column of a 'Systems' list, which is pre-populated with all versions of webpart forms. This dropdown menu 'SystemID' should select the version of the webpart page it is in as the default value. I need a JQuery solution for this, or even Javascript. I am finding it difficult as I am new to both JQuery and Sharepoint. I am using SP2007. I'll appreciate any guidance in solving this. At the moment the Create New Item form of the Calender list has the 'SystemID' drop down list pre-populated with the versions from the Systems list. If anyhthing is unclear pls let me know and I'll explain in more detail.

  Read the article

• creating a heirarchy of terminals or workspaces

  - by intuited

  <rant This question occurred to me ('occurred' meaning 'whispered seductively in my ear for the 100th time') while using GNU-screen, so I'll make that my example. However this is a much more general question about user interfaces and what I perceive as a flawmissing feature in every implementation I've yet seen. I'm wondering if there is some way to create a heirarchy/tree of terminals in a screen session. EG I'd like to have something like 1 bash 1.1 bash 1.2 bash 2 bash 3 bash 3.1 bash 3.1.1 bash 3.1.2 bash It would be good if the terminals could be labelled instead of having to be navigated to via some arrangement that I suspect doesn't exist. So then you could jump to one using eg ^A:goto happydays or ^A:goto dykstra.angry. So to generalize that: Firefox, Chrome, Internet Explorer, gnome-terminal, roxterm, konsole, yakuake, OpenOffice, Microsoft Office, Mr. Snuffaluppagus's Funtime Carousel™, and Your Mom's Jam Browser™ all offer the ability to create a flat set of tabs containing documents of an identical nature: web pages, terminals, documents, fun rideable animals, and jams. GNU-screen implements the same functionality without using tabs. Linux and OS/X window managers provide the ability to organize windows into an array of workspaces, which amounts to again, the same deal. Over the past few years, this has become a more or less ubiquitous concept which has been righteously welcomed into the far reaches of the computer interface funfest. Heavy users of these systems quickly encounter a problem with it: the set of entities is flat. In the case of workspaces, an option may be available to create a 2d array. However none of these applications furnish their users with the ability to create heirarchies, similar to filesystem directory structures, containing instances of their particular contained type. I for one am consistently bothered by this, and am wondering if the community can offer some wisdom as to why this has not happened in any of the foremost collections of computational functionality our culture has yet produced. Or if perhaps it has and I'm just an ignorant savage. I'd like to be able to not only group things into a tree structure, but also to create references (aka symbolic links, aka pointers) from one part of the structure to another, as well as apply properties (eg default directory, colorscheme, ...) recursively downward from a given node. I see no reason why we shouldn't be able to save these structures as known sessions, and apply tags to particular instances. So then you can sort through them by tag, find them by name, or just use the arrow keys (with an appropriate modifier) to move left or right and in or out of a given level. Another key combo would serve to create a branch in the place of the current terminal/webpage/lifelike statue/spreadsheet/spreadsheet sheet/presentation/jam and move that entity into the new branch, then create a fresh one as a sibling to it: a second leaf node within the same branch node. They would get along well. I find it a bit astonishing that this hasn't happened yet, and the only reason I can venture as a guess is that the creators of these fine systems do not consider such functionality to be useful to a significant portion of their userbase. I posit that the probability that that such an assumption would be correct is pretty low. On the other hand, given the relative ease with which such structures can be implemented using modern libraries/languages, it doesn't seem likely that difficulty of implementation would be a major roadblock. If it could be done in 1972 or whenever within the constraints of a filesystem driver, it should be relatively painless to implement in 2010 in a fullblown application. Given that all of these systems are capable of maintaining a set of equivalent entities, it seems unlikely that a major infrastructure overhaul would be necessary in order to enable a navigable heirarchy of them. </rant Mostly I'm just looking to start up a discussion and/or brainstorming on this topic. Any ideas, examples, criticism, or analysis are quite welcome. * Mr. Snuffaluppagus's Funtime Carousel is a registered trademark of Children's Television Workshop Inc. * Your Mom's Jam Browser is a registered trademark of Your Mom Inc.

  Read the article

• Did a recent WinXP update break CD/DVD read speeds? SP2/SP3

  - by quack quixote

  I have two systems with fresh installations of Windows XP Pro SP3 (SP3 slipstreamed into the installer; fully updated after install). One's a refurbished 2.4GHz Pentium4 system; the other is a new 1.6GHz Atom330 build. Both have brand-new dual-layer CD/DVD burners (one's a LiteOn IDE, the other an LG SATA). Both take a really looooong time to read a single-layer DVD in Windows with Cygwin tools. Specifically, 40 minutes or more. I burn backup data to single-layer DVD+/-R and use MD5 hashes for data verification (made with the standard md5sum tool in Unix or Cygwin). The hashes are burned to disc with the data files, and I use this command to verify: $ cd /path/to/disc/mountpoint ; time md5sum -c < md5.txt Here's how long that takes to run on a full single-layer DVD+/-R disc: Old system (WinXP SP2, 1.8GHz Athlon 2500+, last summer): ~10 minutes Old system (Ubuntu 9.04, 1.8GHz Athlon 2500+): ~10 minutes Old system (Debian 5, dual 550MHz P3): ~10 minutes New Pentium4 system (running Ubuntu 9.04): ~5 minutes New Pentium4 system (running WinXP SP3, file copy from Win Explorer): ~6 minutes New Atom330 system (running WinXP SP3, file copy from Win Explorer): ~6 minutes Now the weird stuff: Old system (WinXP SP2, 1.8GHz Athlon 2500+, today): ~25 minutes New Pentium4 system (running WinXP SP3, read from Cygwin): ~40-50 minutes (?!!) New Atom330 system (running WinXP SP3, read from Cygwin): ~40 minutes (can do it in ~30 minutes ...if i have another program spin up the drive first) Since both systems will copy files in 6 minutes using Windows Explorer, I know it's not a hardware problem. Windows just never spins up the drive during the Cygwin read, so it stays super-slow the whole time. Other programs like EAC and DVD Decrypter seem to spin up the disc just fine during their processing. DMA is enabled on both systems. (Can confirm in Windows' Device Manager on the Atom330, not on the P4.) Nero's DriveSpeed tool doesn't seem to have any effect. Copy times are comparable from commandline with Windows' xcopy. Copying with Cygwin's cp looks more like the problem state -- it will spin up the drive for a short time, never reaches full speed, and lets it spin back down again for most of the copy. What I need is to get full read speeds from Cygwin. Is this a known issue with SP3 or some other recent Windows update? Any other ideas? Update: More testing; Windows will spin up the drive when data is copied with Windows tools, but not when read in place or copied with Cygwin tools. It doesn't make sense to me that Windows spins up the drive for copying, but not for other reads. Might be more of a Cygwin problem? Update 2: GUI activity is sluggish during the problem state -- during the Cygwin verifies, there's a slight but noticable delay when dragging windows or icons around on the desktop, switching windows, Alt-Tabbing through open applications, opening new windows, etc. It reminds me of the delay when opening a Windows Explorer window on My Computer just after inserting a DVD. I've tried updating Cygwin (from 1.5.x to 1.7.x), but no change in the problem behavior. I've also noticed this issue occurs on WinXP SP2, but it's not exactly the same -- some spin-up occurs, so the read happens in ~25-30 minutes instead of 40+. The SP2 system used to run the verifies in ~10 minutes, and when it first changed (not sure exactly when, maybe in late November or early December 2009) I thought it was dying hardware. This is why I suspect an official update of breaking this functionality; this has worked for years on that SP2 box.

  Read the article

• Lustre - issues with simple setup

  - by ethrbunny

  Issue: I'm trying to assess the (possible) use of Lustre for our group. To this end I've been trying to create a simple system to explore the nuances. I can't seem to get past the 'llmount.sh' test with any degree of success. What I've done: Each system (throwaway PCs with 70Gb HD, 2Gb RAM) is formatted with CentOS 6.2. I then update everything and install the Lustre kernel from downloads.whamcloud.com and add on the various (appropriate) lustre and e2fs RPM files. Systems are rebooted and tested with 'llmount.sh' (and then cleared with 'llmountcleanup.sh'). All is well to this point. First I create an MDS/MDT system via: /usr/sbin/mkfs.lustre --mgs --mdt --fsname=lustre --device-size=200000 --param sys.timeout=20 --mountfsoptions=errors=remount-ro,user_xattr,acl --param lov.stripesize=1048576 --param lov.stripecount=0 --param mdt.identity_upcall=/usr/sbin/l_getidentity --backfstype ldiskfs --reformat /tmp/lustre-mdt1 and then mkdir -p /mnt/mds1 mount -t lustre -o loop,user_xattr,acl /tmp/lustre-mdt1 /mnt/mds1 Next I take 3 systems and create a 2Gb loop mount via: /usr/sbin/mkfs.lustre --ost --fsname=lustre --device-size=200000 --param sys.timeout=20 --mgsnode=lustre_MDS0@tcp --backfstype ldiskfs --reformat /tmp/lustre-ost1 mkdir -p /mnt/ost1 mount -t lustre -o loop /tmp/lustre-ost1 /mnt/ost1 The logs on the MDT box show the OSS boxes connecting up. All appears ok. Last I create a client and attach to the MDT box: mkdir -p /mnt/lustre mount -t lustre -o user_xattr,acl,flock luster_MDS0@tcp:/lustre /mnt/lustre Again, the log on the MDT box shows the client connection. Appears to be successful. Here's where the issues (appear to) start. If I do a 'df -h' on the client it hangs after showing the system drives. If I attempt to create files (via 'dd') on the lustre mount the session hangs and the job can't be killed. Rebooting the client is the only solution. If I do a 'lctl dl' from the client it shows that only 2/3 OST boxes are found and 'UP'. [root@lfsclient0 etc]# lctl dl 0 UP mgc MGC10.127.24.42@tcp 282d249f-fcb2-b90f-8c4e-2f1415485410 5 1 UP lov lustre-clilov-ffff880037e4d400 00fc176e-3156-0490-44e1-da911be9f9df 4 2 UP lmv lustre-clilmv-ffff880037e4d400 00fc176e-3156-0490-44e1-da911be9f9df 4 3 UP mdc lustre-MDT0000-mdc-ffff880037e4d400 00fc176e-3156-0490-44e1-da911be9f9df 5 4 UP osc lustre-OST0000-osc-ffff880037e4d400 00fc176e-3156-0490-44e1-da911be9f9df 5 5 UP osc lustre-OST0003-osc-ffff880037e4d400 00fc176e-3156-0490-44e1-da911be9f9df 5 Doing a 'lfs df' from the client shows: [root@lfsclient0 etc]# lfs df UUID 1K-blocks Used Available Use% Mounted on lustre-MDT0000_UUID 149944 16900 123044 12% /mnt/lustre[MDT:0] OST0000 : inactive device OST0001 : Resource temporarily unavailable OST0002 : Resource temporarily unavailable lustre-OST0003_UUID 187464 24764 152636 14% /mnt/lustre[OST:3] filesystem summary: 187464 24764 152636 14% /mnt/lustre Given that each OSS box has a 2Gb (loop) mount I would expect to see this reflected in available size. There are no errors on the MDS/MDT box to indicate that multiple OSS/OST boxes have been lost. EDIT: each system has all other systems defined in /etc/hosts and entries in iptables to provide access. SO: I'm clearly making several mistakes. Any pointers as to where to start correcting them?

  Read the article

• Ajax Control Toolkit and Superexpert

  - by Stephen Walther

  Microsoft has asked my company, Superexpert Consulting, to take ownership of the development and maintenance of the Ajax Control Toolkit moving forward. In this blog entry, I discuss our strategy for improving the Ajax Control Toolkit. Why the Ajax Control Toolkit? The Ajax Control Toolkit is one of the most popular projects on CodePlex. In fact, some have argued that it is among the most successful open-source projects of all time. It consistently receives over 3,500 downloads a day (not weekends -- workdays). A mind-boggling number of developers use the Ajax Control Toolkit in their ASP.NET Web Forms applications. Why does the Ajax Control Toolkit continue to be such a popular project? The Ajax Control Toolkit fills a strong need in the ASP.NET Web Forms world. The Toolkit enables Web Forms developers to build richly interactive JavaScript applications without writing any JavaScript. For example, by taking advantage of the Ajax Control Toolkit, a Web Forms developer can add modal dialogs, popup calendars, and client tabs to a web application simply by dragging web controls onto a page. The Ajax Control Toolkit is not for everyone. If you are comfortable writing JavaScript then I recommend that you investigate using jQuery plugins instead of the Ajax Control Toolkit. However, if you are a Web Forms developer and you don’t want to get your hands dirty writing JavaScript, then the Ajax Control Toolkit is a great solution. The Ajax Control Toolkit is Vast The Ajax Control Toolkit consists of 40 controls. That’s a lot of controls (For the sake of comparison, jQuery UI consists of only 8 controls – those slackers J). Furthermore, developers expect the Ajax Control Toolkit to work on browsers both old and new. For example, people expect the Ajax Control Toolkit to work with Internet Explorer 6 and Internet Explorer 9 and every version of Internet Explorer in between. People also expect the Ajax Control Toolkit to work on the latest versions of Mozilla Firefox, Apple Safari, and Google Chrome. And, people expect the Ajax Control Toolkit to work with different operating systems. Yikes, that is a lot of combinations. The biggest challenge which my company faces in supporting the Ajax Control Toolkit is ensuring that the Ajax Control Toolkit works across all of these different browsers and operating systems. Testing, Testing, Testing Because we wanted to ensure that we could easily test the Ajax Control Toolkit with different browsers, the very first thing that we did was to set up a dedicated testing server. The dedicated server -- named Schizo -- hosts 4 virtual machines so that we can run Internet Explorer 6, Internet Explorer 7, Internet Explorer 8, and Internet Explorer 9 at the same time (We also use the virtual machines to host the latest versions of Firefox, Chrome, Opera, and Safari). The five developers on our team (plus me) can each publish to a separate FTP website on the testing server. That way, we can quickly test how changes to the Ajax Control Toolkit affect different browsers. QUnit Tests for the Ajax Control Toolkit Introducing regressions – introducing new bugs when trying to fix existing bugs – is the concern which prevents me from sleeping well at night. There are so many people using the Ajax Control Toolkit in so many unique scenarios, that it is difficult to make improvements to the Ajax Control Toolkit without introducing regressions. In order to avoid regressions, we decided early on that it was extremely important to build good test coverage for the 40 controls in the Ajax Control Toolkit. We’ve been focusing a lot of energy on building automated JavaScript unit tests which we can use to help us discover regressions. We decided to write the unit tests with the QUnit test framework. We picked QUnit because it is quickly becoming the standard unit testing framework in the JavaScript world. For example, it is the unit testing framework used by the jQuery team, the jQuery UI team, and many jQuery UI plugin developers. We had to make several enhancements to the QUnit framework in order to test the Ajax Control Toolkit. For example, QUnit does not support tests which include postbacks. We modified the QUnit framework so that it works with IFrames so we could perform postbacks in our automated tests. At this point, we have written hundreds of QUnit tests. For example, we have written 135 QUnit tests for the Accordion control. The QUnit tests are included with the Ajax Control Toolkit source code in a project named AjaxControlToolkit.Tests. You can run all of the QUnit tests contained in the project by opening the Default.aspx page. Automating the QUnit Tests across Multiple Browsers Automated tests are useless if no one ever runs them. In order for the QUnit tests to be useful, we needed an easy way to run the tests automatically against a matrix of browsers. We wanted to run the unit tests against Internet Explorer 6, Internet Explorer 7, Internet Explorer 8, Internet Explorer 9, Firefox, Chrome, and Safari automatically. Expecting a developer to run QUnit tests against every browser after every check-in is just too much to expect. It takes 20 seconds to run the Accordion QUnit tests. We are testing against 8 browsers. That would require the developer to open 8 browsers and wait for the results after each change in code. Too much work. Therefore, we built a JavaScript Test Server. Our JavaScript Test Server project was inspired by John Resig’s TestSwarm project. The JavaScript Test Server runs our QUnit tests in a swarm of browsers (running on different operating systems) automatically. Here’s how the JavaScript Test Server works: 1. We created an ASP.NET page named RunTest.aspx that constantly polls the JavaScript Test Server for a new set of QUnit tests to run. After the RunTest.aspx page runs the QUnit tests, the RunTest.aspx records the test results back to the JavaScript Test Server. 2. We opened the RunTest.aspx page on instances of Internet Explorer 6, Internet Explorer 7, Internet Explorer 8, Internet Explorer 9, FireFox, Chrome, Opera, Google, and Safari. Now that we have the JavaScript Test Server setup, we can run all of our QUnit tests against all of the browsers which we need to support with a single click of a button. A New Release of the Ajax Control Toolkit Each Month The Ajax Control Toolkit Issue Tracker contains over one thousand five hundred open issues and feature requests. So we have plenty of work on our plates J At CodePlex, anyone can vote for an issue to be fixed. Originally, we planned to fix issues in order of their votes. However, we quickly discovered that this approach was inefficient. Constantly switching back and forth between different controls was too time-consuming. It takes time to re-familiarize yourself with a control. Instead, we decided to focus on two or three controls each month and really focus on fixing the issues with those controls. This way, we can fix sets of related issues and avoid the randomization caused by context switching. Our team works in monthly sprints. We plan to do another release of the Ajax Control Toolkit each and every month. So far, we have competed one release of the Ajax Control Toolkit which was released on April 1, 2011. We plan to release a new version in early May. Conclusion Fortunately, I work with a team of smart developers. We currently have 5 developers working on the Ajax Control Toolkit (not full-time, they are also building two very cool ASP.NET MVC applications). All the developers who work on our team are required to have strong JavaScript, jQuery, and ASP.NET MVC skills. In the interest of being as transparent as possible about our work on the Ajax Control Toolkit, I plan to blog frequently about our team’s ongoing work. In my next blog entry, I plan to write about the two Ajax Control Toolkit controls which are the focus of our work for next release.

  Read the article

• Ask the Readers: Do You Use the Command Line?

  - by Asian Angel

  Most people have heard of it but not everyone is familiar or comfortable with how to use this bastion of geekdom. This week we would like to know if you use the command line or not. The command line…the bastion of ultimate geekery in many peoples’ eyes. You often hear people referring to doing things using the command line, so there must be something to it, right? For some people using the command line is the best, most efficient, and easiest way to do things on their systems. These are the people that many of us wish we were like. Next you have those who are proficient at using the command line but do not rely on it for everything they do on their systems. Then there are people who know how to perform some tasks or hacks using the command line but may not be as comfortable or knowledgeable as they wish to be using it. Moving on you find those who are interested in learning how to use the command line and just need a small push to get started.  Perhaps you feel too intimidated to learn it and just need the right opportunity to come along. And maybe you do not care one way or the other so long as you get done what you want to do on your system. Or you may prefer to simply use a graphical interface since that is quicker and easier for you (along with being familiar). You can find the whole range of people when it comes to using the command line… This week we would like to know if you use the command line or not. What command line category do you fit into? Power user? Casual usage? Totally lost? Let us know in the comments! How-To Geek Polls require Javascript. Please Click Here to View the Poll. Latest Features How-To Geek ETC The How-To Geek Holiday Gift Guide (Geeky Stuff We Like) LCD? LED? Plasma? The How-To Geek Guide to HDTV Technology The How-To Geek Guide to Learning Photoshop, Part 8: Filters Improve Digital Photography by Calibrating Your Monitor Our Favorite Tech: What We’re Thankful For at How-To Geek The How-To Geek Guide to Learning Photoshop, Part 7: Design and Typography Fun and Colorful Firefox Theme for Windows 7 Happy Snow Bears Theme for Chrome and Iron [Holiday] Download Full Command and Conquer: Tiberian Sun Game for Free Scorched Cometary Planet Wallpaper Quick Fix: Add the RSS Button Back to the Firefox Awesome Bar Dropbox Desktop Client 1.0.0 RC for Windows, Linux, and Mac Released

  Read the article

• A Taxonomy of Numerical Methods v1

  - by JoshReuben

  Numerical Analysis – When, What, (but not how) Once you understand the Math & know C++, Numerical Methods are basically blocks of iterative & conditional math code. I found the real trick was seeing the forest for the trees – knowing which method to use for which situation. Its pretty easy to get lost in the details – so I’ve tried to organize these methods in a way that I can quickly look this up. I’ve included links to detailed explanations and to C++ code examples. I’ve tried to classify Numerical methods in the following broad categories: Solving Systems of Linear Equations Solving Non-Linear Equations Iteratively Interpolation Curve Fitting Optimization Numerical Differentiation & Integration Solving ODEs Boundary Problems Solving EigenValue problems Enjoy – I did ! Solving Systems of Linear Equations Overview Solve sets of algebraic equations with x unknowns The set is commonly in matrix form Gauss-Jordan Elimination http://en.wikipedia.org/wiki/Gauss%E2%80%93Jordan_elimination C++: http://www.codekeep.net/snippets/623f1923-e03c-4636-8c92-c9dc7aa0d3c0.aspx Produces solution of the equations & the coefficient matrix Efficient, stable 2 steps: · Forward Elimination – matrix decomposition: reduce set to triangular form (0s below the diagonal) or row echelon form. If degenerate, then there is no solution · Backward Elimination –write the original matrix as the product of ints inverse matrix & its reduced row-echelon matrix à reduce set to row canonical form & use back-substitution to find the solution to the set Elementary ops for matrix decomposition: · Row multiplication · Row switching · Add multiples of rows to other rows Use pivoting to ensure rows are ordered for achieving triangular form LU Decomposition http://en.wikipedia.org/wiki/LU_decomposition C++: http://ganeshtiwaridotcomdotnp.blogspot.co.il/2009/12/c-c-code-lu-decomposition-for-solving.html Represent the matrix as a product of lower & upper triangular matrices A modified version of GJ Elimination Advantage – can easily apply forward & backward elimination to solve triangular matrices Techniques: · Doolittle Method – sets the L matrix diagonal to unity · Crout Method - sets the U matrix diagonal to unity Note: both the L & U matrices share the same unity diagonal & can be stored compactly in the same matrix Gauss-Seidel Iteration http://en.wikipedia.org/wiki/Gauss%E2%80%93Seidel_method C++: http://www.nr.com/forum/showthread.php?t=722 Transform the linear set of equations into a single equation & then use numerical integration (as integration formulas have Sums, it is implemented iteratively). an optimization of Gauss-Jacobi: 1.5 times faster, requires 0.25 iterations to achieve the same tolerance Solving Non-Linear Equations Iteratively find roots of polynomials – there may be 0, 1 or n solutions for an n order polynomial use iterative techniques Iterative methods · used when there are no known analytical techniques · Requires set functions to be continuous & differentiable · Requires an initial seed value – choice is critical to convergence à conduct multiple runs with different starting points & then select best result · Systematic - iterate until diminishing returns, tolerance or max iteration conditions are met · bracketing techniques will always yield convergent solutions, non-bracketing methods may fail to converge Incremental method if a nonlinear function has opposite signs at 2 ends of a small interval x1 & x2, then there is likely to be a solution in their interval – solutions are detected by evaluating a function over interval steps, for a change in sign, adjusting the step size dynamically. Limitations – can miss closely spaced solutions in large intervals, cannot detect degenerate (coinciding) solutions, limited to functions that cross the x-axis, gives false positives for singularities Fixed point method http://en.wikipedia.org/wiki/Fixed-point_iteration C++: http://books.google.co.il/books?id=weYj75E_t6MC&pg=PA79&lpg=PA79&dq=fixed+point+method++c%2B%2B&source=bl&ots=LQ-5P_taoC&sig=lENUUIYBK53tZtTwNfHLy5PEWDk&hl=en&sa=X&ei=wezDUPW1J5DptQaMsIHQCw&redir_esc=y#v=onepage&q=fixed%20point%20method%20%20c%2B%2B&f=false Algebraically rearrange a solution to isolate a variable then apply incremental method Bisection method http://en.wikipedia.org/wiki/Bisection_method C++: http://numericalcomputing.wordpress.com/category/algorithms/ Bracketed - Select an initial interval, keep bisecting it ad midpoint into sub-intervals and then apply incremental method on smaller & smaller intervals – zoom in Adv: unaffected by function gradient à reliable Disadv: slow convergence False Position Method http://en.wikipedia.org/wiki/False_position_method C++: http://www.dreamincode.net/forums/topic/126100-bisection-and-false-position-methods/ Bracketed - Select an initial interval , & use the relative value of function at interval end points to select next sub-intervals (estimate how far between the end points the solution might be & subdivide based on this) Newton-Raphson method http://en.wikipedia.org/wiki/Newton's_method C++: http://www-users.cselabs.umn.edu/classes/Summer-2012/csci1113/index.php?page=./newt3 Also known as Newton's method Convenient, efficient Not bracketed – only a single initial guess is required to start iteration – requires an analytical expression for the first derivative of the function as input. Evaluates the function & its derivative at each step. Can be extended to the Newton MutiRoot method for solving multiple roots Can be easily applied to an of n-coupled set of non-linear equations – conduct a Taylor Series expansion of a function, dropping terms of order n, rewrite as a Jacobian matrix of PDs & convert to simultaneous linear equations !!! Secant Method http://en.wikipedia.org/wiki/Secant_method C++: http://forum.vcoderz.com/showthread.php?p=205230 Unlike N-R, can estimate first derivative from an initial interval (does not require root to be bracketed) instead of inputting it Since derivative is approximated, may converge slower. Is fast in practice as it does not have to evaluate the derivative at each step. Similar implementation to False Positive method Birge-Vieta Method http://mat.iitm.ac.in/home/sryedida/public_html/caimna/transcendental/polynomial%20methods/bv%20method.html C++: http://books.google.co.il/books?id=cL1boM2uyQwC&pg=SA3-PA51&lpg=SA3-PA51&dq=Birge-Vieta+Method+c%2B%2B&source=bl&ots=QZmnDTK3rC&sig=BPNcHHbpR_DKVoZXrLi4nVXD-gg&hl=en&sa=X&ei=R-_DUK2iNIjzsgbE5ID4Dg&redir_esc=y#v=onepage&q=Birge-Vieta%20Method%20c%2B%2B&f=false combines Horner's method of polynomial evaluation (transforming into lesser degree polynomials that are more computationally efficient to process) with Newton-Raphson to provide a computational speed-up Interpolation Overview Construct new data points for as close as possible fit within range of a discrete set of known points (that were obtained via sampling, experimentation) Use Taylor Series Expansion of a function f(x) around a specific value for x Linear Interpolation http://en.wikipedia.org/wiki/Linear_interpolation C++: http://www.hamaluik.com/?p=289 Straight line between 2 points à concatenate interpolants between each pair of data points Bilinear Interpolation http://en.wikipedia.org/wiki/Bilinear_interpolation C++: http://supercomputingblog.com/graphics/coding-bilinear-interpolation/2/ Extension of the linear function for interpolating functions of 2 variables – perform linear interpolation first in 1 direction, then in another. Used in image processing – e.g. texture mapping filter. Uses 4 vertices to interpolate a value within a unit cell. Lagrange Interpolation http://en.wikipedia.org/wiki/Lagrange_polynomial C++: http://www.codecogs.com/code/maths/approximation/interpolation/lagrange.php For polynomials Requires recomputation for all terms for each distinct x value – can only be applied for small number of nodes Numerically unstable Barycentric Interpolation http://epubs.siam.org/doi/pdf/10.1137/S0036144502417715 C++: http://www.gamedev.net/topic/621445-barycentric-coordinates-c-code-check/ Rearrange the terms in the equation of the Legrange interpolation by defining weight functions that are independent of the interpolated value of x Newton Divided Difference Interpolation http://en.wikipedia.org/wiki/Newton_polynomial C++: http://jee-appy.blogspot.co.il/2011/12/newton-divided-difference-interpolation.html Hermite Divided Differences: Interpolation polynomial approximation for a given set of data points in the NR form - divided differences are used to approximately calculate the various differences. For a given set of 3 data points , fit a quadratic interpolant through the data Bracketed functions allow Newton divided differences to be calculated recursively Difference table Cubic Spline Interpolation http://en.wikipedia.org/wiki/Spline_interpolation C++: https://www.marcusbannerman.co.uk/index.php/home/latestarticles/42-articles/96-cubic-spline-class.html Spline is a piecewise polynomial Provides smoothness – for interpolations with significantly varying data Use weighted coefficients to bend the function to be smooth & its 1st & 2nd derivatives are continuous through the edge points in the interval Curve Fitting A generalization of interpolating whereby given data points may contain noise à the curve does not necessarily pass through all the points Least Squares Fit http://en.wikipedia.org/wiki/Least_squares C++: http://www.ccas.ru/mmes/educat/lab04k/02/least-squares.c Residual – difference between observed value & expected value Model function is often chosen as a linear combination of the specified functions Determines: A) The model instance in which the sum of squared residuals has the least value B) param values for which model best fits data Straight Line Fit Linear correlation between independent variable and dependent variable Linear Regression http://en.wikipedia.org/wiki/Linear_regression C++: http://www.oocities.org/david_swaim/cpp/linregc.htm Special case of statistically exact extrapolation Leverage least squares Given a basis function, the sum of the residuals is determined and the corresponding gradient equation is expressed as a set of normal linear equations in matrix form that can be solved (e.g. using LU Decomposition) Can be weighted - Drop the assumption that all errors have the same significance –-> confidence of accuracy is different for each data point. Fit the function closer to points with higher weights Polynomial Fit - use a polynomial basis function Moving Average http://en.wikipedia.org/wiki/Moving_average C++: http://www.codeproject.com/Articles/17860/A-Simple-Moving-Average-Algorithm Used for smoothing (cancel fluctuations to highlight longer-term trends & cycles), time series data analysis, signal processing filters Replace each data point with average of neighbors. Can be simple (SMA), weighted (WMA), exponential (EMA). Lags behind latest data points – extra weight can be given to more recent data points. Weights can decrease arithmetically or exponentially according to distance from point. Parameters: smoothing factor, period, weight basis Optimization Overview Given function with multiple variables, find Min (or max by minimizing –f(x)) Iterative approach Efficient, but not necessarily reliable Conditions: noisy data, constraints, non-linear models Detection via sign of first derivative - Derivative of saddle points will be 0 Local minima Bisection method Similar method for finding a root for a non-linear equation Start with an interval that contains a minimum Golden Search method http://en.wikipedia.org/wiki/Golden_section_search C++: http://www.codecogs.com/code/maths/optimization/golden.php Bisect intervals according to golden ratio 0.618.. Achieves reduction by evaluating a single function instead of 2 Newton-Raphson Method Brent method http://en.wikipedia.org/wiki/Brent's_method C++: http://people.sc.fsu.edu/~jburkardt/cpp_src/brent/brent.cpp Based on quadratic or parabolic interpolation – if the function is smooth & parabolic near to the minimum, then a parabola fitted through any 3 points should approximate the minima – fails when the 3 points are collinear , in which case the denominator is 0 Simplex Method http://en.wikipedia.org/wiki/Simplex_algorithm C++: http://www.codeguru.com/cpp/article.php/c17505/Simplex-Optimization-Algorithm-and-Implemetation-in-C-Programming.htm Find the global minima of any multi-variable function Direct search – no derivatives required At each step it maintains a non-degenerative simplex – a convex hull of n+1 vertices. Obtains the minimum for a function with n variables by evaluating the function at n-1 points, iteratively replacing the point of worst result with the point of best result, shrinking the multidimensional simplex around the best point. Point replacement involves expanding & contracting the simplex near the worst value point to determine a better replacement point Oscillation can be avoided by choosing the 2nd worst result Restart if it gets stuck Parameters: contraction & expansion factors Simulated Annealing http://en.wikipedia.org/wiki/Simulated_annealing C++: http://code.google.com/p/cppsimulatedannealing/ Analogy to heating & cooling metal to strengthen its structure Stochastic method – apply random permutation search for global minima - Avoid entrapment in local minima via hill climbing Heating schedule - Annealing schedule params: temperature, iterations at each temp, temperature delta Cooling schedule – can be linear, step-wise or exponential Differential Evolution http://en.wikipedia.org/wiki/Differential_evolution C++: http://www.amichel.com/de/doc/html/ More advanced stochastic methods analogous to biological processes: Genetic algorithms, evolution strategies Parallel direct search method against multiple discrete or continuous variables Initial population of variable vectors chosen randomly – if weighted difference vector of 2 vectors yields a lower objective function value then it replaces the comparison vector Many params: #parents, #variables, step size, crossover constant etc Convergence is slow – many more function evaluations than simulated annealing Numerical Differentiation Overview 2 approaches to finite difference methods: · A) approximate function via polynomial interpolation then differentiate · B) Taylor series approximation – additionally provides error estimate Finite Difference methods http://en.wikipedia.org/wiki/Finite_difference_method C++: http://www.wpi.edu/Pubs/ETD/Available/etd-051807-164436/unrestricted/EAMPADU.pdf Find differences between high order derivative values - Approximate differential equations by finite differences at evenly spaced data points Based on forward & backward Taylor series expansion of f(x) about x plus or minus multiples of delta h. Forward / backward difference - the sums of the series contains even derivatives and the difference of the series contains odd derivatives – coupled equations that can be solved. Provide an approximation of the derivative within a O(h^2) accuracy There is also central difference & extended central difference which has a O(h^4) accuracy Richardson Extrapolation http://en.wikipedia.org/wiki/Richardson_extrapolation C++: http://mathscoding.blogspot.co.il/2012/02/introduction-richardson-extrapolation.html A sequence acceleration method applied to finite differences Fast convergence, high accuracy O(h^4) Derivatives via Interpolation Cannot apply Finite Difference method to discrete data points at uneven intervals – so need to approximate the derivative of f(x) using the derivative of the interpolant via 3 point Lagrange Interpolation Note: the higher the order of the derivative, the lower the approximation precision Numerical Integration Estimate finite & infinite integrals of functions More accurate procedure than numerical differentiation Use when it is not possible to obtain an integral of a function analytically or when the function is not given, only the data points are Newton Cotes Methods http://en.wikipedia.org/wiki/Newton%E2%80%93Cotes_formulas C++: http://www.siafoo.net/snippet/324 For equally spaced data points Computationally easy – based on local interpolation of n rectangular strip areas that is piecewise fitted to a polynomial to get the sum total area Evaluate the integrand at n+1 evenly spaced points – approximate definite integral by Sum Weights are derived from Lagrange Basis polynomials Leverage Trapezoidal Rule for default 2nd formulas, Simpson 1/3 Rule for substituting 3 point formulas, Simpson 3/8 Rule for 4 point formulas. For 4 point formulas use Bodes Rule. Higher orders obtain more accurate results Trapezoidal Rule uses simple area, Simpsons Rule replaces the integrand f(x) with a quadratic polynomial p(x) that uses the same values as f(x) for its end points, but adds a midpoint Romberg Integration http://en.wikipedia.org/wiki/Romberg's_method C++: http://code.google.com/p/romberg-integration/downloads/detail?name=romberg.cpp&can=2&q= Combines trapezoidal rule with Richardson Extrapolation Evaluates the integrand at equally spaced points The integrand must have continuous derivatives Each R(n,m) extrapolation uses a higher order integrand polynomial replacement rule (zeroth starts with trapezoidal) à a lower triangular matrix set of equation coefficients where the bottom right term has the most accurate approximation. The process continues until the difference between 2 successive diagonal terms becomes sufficiently small. Gaussian Quadrature http://en.wikipedia.org/wiki/Gaussian_quadrature C++: http://www.alglib.net/integration/gaussianquadratures.php Data points are chosen to yield best possible accuracy – requires fewer evaluations Ability to handle singularities, functions that are difficult to evaluate The integrand can include a weighting function determined by a set of orthogonal polynomials. Points & weights are selected so that the integrand yields the exact integral if f(x) is a polynomial of degree <= 2n+1 Techniques (basically different weighting functions): · Gauss-Legendre Integration w(x)=1 · Gauss-Laguerre Integration w(x)=e^-x · Gauss-Hermite Integration w(x)=e^-x^2 · Gauss-Chebyshev Integration w(x)= 1 / Sqrt(1-x^2) Solving ODEs Use when high order differential equations cannot be solved analytically Evaluated under boundary conditions RK for systems – a high order differential equation can always be transformed into a coupled first order system of equations Euler method http://en.wikipedia.org/wiki/Euler_method C++: http://rosettacode.org/wiki/Euler_method First order Runge–Kutta method. Simple recursive method – given an initial value, calculate derivative deltas. Unstable & not very accurate (O(h) error) – not used in practice A first-order method - the local error (truncation error per step) is proportional to the square of the step size, and the global error (error at a given time) is proportional to the step size In evolving solution between data points xn & xn+1, only evaluates derivatives at beginning of interval xn à asymmetric at boundaries Higher order Runge Kutta http://en.wikipedia.org/wiki/Runge%E2%80%93Kutta_methods C++: http://www.dreamincode.net/code/snippet1441.htm 2nd & 4th order RK - Introduces parameterized midpoints for more symmetric solutions à accuracy at higher computational cost Adaptive RK – RK-Fehlberg – estimate the truncation at each integration step & automatically adjust the step size to keep error within prescribed limits. At each step 2 approximations are compared – if in disagreement to a specific accuracy, the step size is reduced Boundary Value Problems Where solution of differential equations are located at 2 different values of the independent variable x à more difficult, because cannot just start at point of initial value – there may not be enough starting conditions available at the end points to produce a unique solution An n-order equation will require n boundary conditions – need to determine the missing n-1 conditions which cause the given conditions at the other boundary to be satisfied Shooting Method http://en.wikipedia.org/wiki/Shooting_method C++: http://ganeshtiwaridotcomdotnp.blogspot.co.il/2009/12/c-c-code-shooting-method-for-solving.html Iteratively guess the missing values for one end & integrate, then inspect the discrepancy with the boundary values of the other end to adjust the estimate Given the starting boundary values u1 & u2 which contain the root u, solve u given the false position method (solving the differential equation as an initial value problem via 4th order RK), then use u to solve the differential equations. Finite Difference Method For linear & non-linear systems Higher order derivatives require more computational steps – some combinations for boundary conditions may not work though Improve the accuracy by increasing the number of mesh points Solving EigenValue Problems An eigenvalue can substitute a matrix when doing matrix multiplication à convert matrix multiplication into a polynomial EigenValue For a given set of equations in matrix form, determine what are the solution eigenvalue & eigenvectors Similar Matrices - have same eigenvalues. Use orthogonal similarity transforms to reduce a matrix to diagonal form from which eigenvalue(s) & eigenvectors can be computed iteratively Jacobi method http://en.wikipedia.org/wiki/Jacobi_method C++: http://people.sc.fsu.edu/~jburkardt/classes/acs2_2008/openmp/jacobi/jacobi.html Robust but Computationally intense – use for small matrices < 10x10 Power Iteration http://en.wikipedia.org/wiki/Power_iteration For any given real symmetric matrix, generate the largest single eigenvalue & its eigenvectors Simplest method – does not compute matrix decomposition à suitable for large, sparse matrices Inverse Iteration Variation of power iteration method – generates the smallest eigenvalue from the inverse matrix Rayleigh Method http://en.wikipedia.org/wiki/Rayleigh's_method_of_dimensional_analysis Variation of power iteration method Rayleigh Quotient Method Variation of inverse iteration method Matrix Tri-diagonalization Method Use householder algorithm to reduce an NxN symmetric matrix to a tridiagonal real symmetric matrix vua N-2 orthogonal transforms     Whats Next Outside of Numerical Methods there are lots of different types of algorithms that I’ve learned over the decades: Data Mining – (I covered this briefly in a previous post: http://geekswithblogs.net/JoshReuben/archive/2007/12/31/ssas-dm-algorithms.aspx ) Search & Sort Routing Problem Solving Logical Theorem Proving Planning Probabilistic Reasoning Machine Learning Solvers (eg MIP) Bioinformatics (Sequence Alignment, Protein Folding) Quant Finance (I read Wilmott’s books – interesting) Sooner or later, I’ll cover the above topics as well.

  Read the article

• Serious about Embedded: Java Embedded @ JavaOne 2012

  - by terrencebarr

  It bears repeating: More than ever, the Java platform is the best technology for many embedded use cases. Java’s platform independence, high level of functionality, security, and developer productivity address the key pain points in building embedded solutions. Transitioning from 16 to 32 bit or even 64 bit? Need to support multiple architectures and operating systems with a single code base? Want to scale on multi-core systems? Require a proven security model? Dynamically deploy and manage software on your devices? Cut time to market by leveraging code, expertise, and tools from a large developer ecosystem? Looking for back-end services, integration, and management? The Java platform has got you covered. Java already powers around 10 billion devices worldwide, with traditional desktops and servers being only a small portion of that. And the ‘Internet of Things‘ is just really starting to explode … it is estimated that within five years, intelligent and connected embedded devices will outnumber desktops and mobile phones combined, and will generate the majority of the traffic on the Internet. Is your platform and services strategy ready for the coming disruptions and opportunities? It should come as no surprise that Oracle is keenly focused on Java for Embedded. At JavaOne 2012 San Francisco the dedicated track for Java ME, Java Card, and Embedded keeps growing, with 52 sessions, tutorials, Hands-on-Labs, and BOFs scheduled for this track alone, plus keynotes, demos, booths, and a variety of other embedded content. To further prove Oracle’s commitment, in 2012 for the first time there will be a dedicated sub-conference focused on the business aspects of embedded Java: Java Embedded @ JavaOne. This conference will run for two days in parallel to JavaOne in San Francisco, will have its own business-oriented track and content, and targets C-level executives, architects, business leaders, and decision makers. Registration and Call For Papers for Java Embedded @ JavaOne are now live. We expect a lot of interest in this new event and space is limited, so be sure to submit your paper and register soon. Hope to see you there! Cheers, – Terrence Filed under: Mobile & Embedded Tagged: ARM, Call for Papers, Embedded Java, Java Embedded, Java Embedded @ JavaOne, Java ME, Java SE Embedded, Java SE for Embedded, JavaOne San Francisco, PowerPC

  Read the article

• SQL SERVER – What is MDS? – Master Data Services in Microsoft SQL Server 2008 R2

  - by pinaldave

  What is MDS? Master Data Services helps enterprises standardize the data people rely on to make critical business decisions. With Master Data Services, IT organizations can centrally manage critical data assets company wide and across diverse systems, enable more people to securely manage master data directly, and ensure the integrity of information over time. (Source: Microsoft) Today I will be talking about the same subject at Microsoft TechEd India. If you want to learn about how to standardize your data and apply the business rules to validate data you must attend my session. MDS is very interesting concept, I will cover super short but very interesting 10 quick slides about this subject. I will make sure in very first 20 mins, you will understand following topics Introduction to Master Data Management What is Master Data and Challenges MDM Challenges and Advantage Microsoft Master Data Services Benefits and Key Features Uses of MDS Capabilities Key Features of MDS This slides decks will be followed by around 30 mins demo which will have story of entity, hierarchies, versions, security, consolidation and collection. I will be tell this story keeping business rules in center. We take one business rule which will be simple validation rule and will make it much more complex and yet very useful to product. I will also demonstrate few real life scenario where I will be talking about MDS and its usage. Do not miss this session. At the end of session there will be book awarded to best participant. My session details: Session: Master Data Services in Microsoft SQL Server 2008 R2 Date: April 12, 2010  Time: 2:30pm-3:30pm SQL Server Master Data Services will ship with SQL Server 2008 R2 and will improve Microsoft’s platform appeal. This session provides an in depth demonstration of MDS features and highlights important usage scenarios. Master Data Services enables consistent decision making by allowing you to create, manage and propagate changes from single master view of your business entities. Also with MDS – Master Data-hub which is the vital component helps ensure reporting consistency across systems and deliver faster more accurate results across the enterprise. We will talk about establishing the basis for a centralized approach to defining, deploying, and managing master data in the enterprise. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Business Intelligence, Data Warehousing, MVP, Pinal Dave, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority Author Visit, T SQL, Technology Tagged: TechEd, TechEdIn

  Read the article

• Tellago is still hiring….

  - by gsusx

  Tellago 's SOA practice is rapidly growing and we are still hiring. In that sense, we are looking to for Connected Systems (WCF, BizTalk, WF) experts who are passionate about building game changing solutions with the latest Microsoft technologies. You will be working alongside technology gurus like DonXml , Pablo Cibraro or Dwight Goins . If you are interested and not afraid of working with a bunch of crazy people ;)please drop me a line at jesus dot rodriguez at tellago dot com. Hope to hear from...(read more)

  Read the article

• Defend Your Servers from the Bad Guys in ‘Install D’

  - by Akemi Iwaya

  If you love playing tower defense games, then you will definitely want to give today’s offering a try. In ‘Install D’, you must defend your servers from all manner of problems such as glitches, bugs, and viruses that are ready to bring your systems to their knees! Can you succeed, or will the IT department be hanging out the ‘Help Wanted’ sign?Click Here to Continue Reading

  Read the article

• EBS 11i and R12 certified with DB 11gR2 11.2.0.1 on Windows

  - by Steven Chan

  Oracle Database 11g Release 2 (11gR2) version 11.2.0.1 is now certified with Oracle E-Business Suite 11i and 12 on the following Microsoft Windows Server (32-bit) and Windows x64 (64-bit) operating systems:Windows Server 2003 (32-bit and 64-bit) Windows Server 2003 R2 (32-bit and 64-bit)Windows Server 2008 (32-bit and 64-bit)Windows Server 2008 R2 (64-bit only)Certified EBS ReleasesOracle E-Business Suite Release 11.5.10.2Oracle E-Business Suite Release 12.0.4 or higherOracle E-Business Suite Release  12.1.1 or higher

  Read the article

• What is the actual difference between Computer Programmers and Software Engineers? Is this description accurate?

  - by Ari

  According to the Bureau of Labor Statistics, this is the difference: Computer programmers write programs. After computer software engineers and systems analysts design software programs, the programmer converts that design into a logical series of instructions that the computer can follow They predict employment to increase for software engineers by 34% but to decline for programmers. Is there actually any such real distinction between the 2 jobs? How can one get a job designing programs (to be implemented by others)?

  Read the article

• AppFabric Caching Feedback

  - by Michael Stephenson

  We are running a survey to collect feedback around scenarios where people were experimenting with velocity on windows 2003 in the CTP but are now in a position where the beta requires windows 2008. We would like to understand how important this scenario is precieved to be. If you are in the Connected Systems Community and would like to provide feedback please complete the following survey http://www.surveymonkey.com/s/N3VKZWN

  Read the article

• Make flash ignore transparent wmode — always display opaque background

  - by Tometzky

  How to make flash movie (an advertising banner) ignore <param name="wmode" value="transparent">? There are some CMS systems which insert flash movies automatically with transparent wmode option. Flash Player ignores banner's background color, makes it transparent and displays it on web page background. I can workaround it using additional layer at the bottom with a large rectangle of desired color, but I think it is inefficient and inelegant. How to do this better?

  Read the article

• Using VMware vCenter Update Manager to keep your vSphere Hosts Up-To-Date with Patching

  The chore of patching operating systems and applications is taking an increasing proportion of the time of a system administrator, so it is a a relief that at least VMware is keen to make the task easier. VMware provide a tool in vCenter Update Manager to assist in keeping VMware up to date. Jonathan Medd explains all.

  Read the article

• Interview with Lenz Grimmer about MySQL Connect

  - by Keith Larson

  Keith Larson: Thank you for allowing me to do this interview with you.  I have been talking with a few different Oracle ACEs   about the MySQL Connect Conference. I figured the MySQL community might be missing you as well. You have been very busy with Oracle Linux but I know you still have an eye on the MySQL Community. How have things been?Lenz Grimmer: Thanks for including me in this series of interviews, I feel honored! I've read the other interviews, and really liked them. I still try to follow what's going on over in the MySQL community and it's good to see that many of the familiar faces are still around. Over the course of the 9 years that I was involved with MySQL, many colleagues and contacts turned into good friends and we still maintain close relationships.It's been almost 1.5 years ago that I moved into my new role here in the Linux team at Oracle, and I really enjoy working on a Linux distribution again (I worked for SUSE before I joined MySQL AB in 2002). I'm still learning a lot - Linux in the data center has greatly evolved in so many ways and there are a lot of new and exciting technologies to explore. Keith Larson: What were your thoughts when you heard that Oracle was going to deliver the MySQL Connect conference to the MySQL Community?Lenz Grimmer: I think it's testament to the fact that Oracle deeply cares about MySQL, despite what many skeptics may say. What started as "MySQL Sunday" two years ago has now evolved into a full-blown sub-conference, with 80 sessions at one of the largest corporate IT events in the world. I find this quite telling, not many products at Oracle enjoy this level of exposure! So it certainly makes me feel proud to see how far MySQL has come. Keith Larson: Have you had a chance to look over the sessions? What are your thoughts on them?Lenz Grimmer: I did indeed look at the final schedule.The content committee did a great job with selecting these sessions. I'm glad to see that the content selection was influenced by involving well-known and respected members of the MySQL community. The sessions cover a broad range of topics and technologies, both covering established topics as well as recent developments. Keith Larson: When you get a chance, what sessions do you plan on attending?Lenz Grimmer: I will actually be manning the Oracle booth in the exhibition area on one of these days, so I'm not sure if I'll have a lot of time attending sessions. But if I do, I'd love to see the keynotes and catch some of the sessions that talk about recent developments and new features in MySQL, High Availability and Clustering . Quite a lot has happened and it's hard to keep up with this constant flow of new MySQL releases.In particular, the following sessions caught my attention: MySQL Connect Keynote: The State of the Dolphin Evaluating MySQL High-Availability Alternatives CERN’s MySQL “as a Service” Deployment with Oracle VM: Empowering Users MySQL 5.6 Replication: Taking Scalability and High Availability to the Next Level What’s New in MySQL Server 5.6? MySQL Security: Past and Present MySQL at Twitter: Development and Deployment MySQL Community BOF MySQL Connect Keynote: MySQL Perspectives Keith Larson: So I will ask you just like I have asked the others I have interviewed, any tips that you would give to people for handling the long hours at conferences?Lenz Grimmer: Wear comfortable shoes and make sure to drink a lot! Also prepare a plan of the sessions you would like to attend beforehand and familiarize yourself with the venue, so you can get to the next talk in time without scrambling to find the location. The good thing about piggybacking on such a large conference like Oracle OpenWorld is that you benefit from the whole infrastructure. For example, there is a nice schedule builder that helps you to keep track of your sessions of interest. Other than that, bring enough business cards and talk to people, build up your network among your peers and other MySQL professionals! Keith Larson: What features of the MySQL 5.6 release do you look forward to the most ?Lenz Grimmer: There has been solid progress in so many areas like the InnoDB Storage Engine, the Optimizer, Replication or Performance Schema, it's hard for me to really highlight anything in particular. All in all, MySQL 5.6 sounds like a very promising release. I'm confident it will follow the tradition that Oracle already established with MySQL 5.5, which received a lot of praise even from very critical members of the MySQL community. If I had to name a single feature, I'm particularly and personally happy that the precise GIS functions have finally made it into a GA release - that was long overdue. Keith Larson:  In your opinion what is the best reason for someone to attend this event?Lenz Grimmer: This conference is an excellent opportunity to get in touch with the key people in the MySQL community and ecosystem and to get facts and information from the domain experts and developers that work on MySQL. The broad range of topics should attract people from a variety of roles and relations to MySQL, beginning with Developers and DBAs, to CIOs considering MySQL as a viable solution for their requirements. Keith Larson: You will be attending MySQL Connect and have some Oracle Linux Demos, do you see a growing demand for MySQL on Oracle Linux ?Lenz Grimmer: Yes! Oracle Linux is our recommended Linux distribution and we have a good relationship to the MySQL engineering group. They use Oracle Linux as a base Linux platform for development and QA, so we make sure that MySQL and Oracle Linux are well tested together. Setting up a MySQL server on Oracle Linux can be done very quickly, and many customers recognize the benefits of using them both in combination.Because Oracle Linux is available for free (including free bug fixes and errata), it's an ideal choice for running MySQL in your data center. You can run the same Linux distribution on both your development/staging systems as well as on the production machines, you decide which of these should be covered by a support subscription and at which level of support. This gives you flexibility and provides some really attractive cost-saving opportunities. Keith Larson: Since I am a Linux user and fan, what is on the horizon for  Oracle Linux?Lenz Grimmer: We're working hard on broadening the ecosystem around Oracle Linux, building up partnerships with ISVs and IHVs to certify Oracle Linux as a fully supported platform for their products. We also continue to collaborate closely with the Linux kernel community on various projects, to make sure that Linux scales and performs well on large systems and meets the demands of today's data centers. These improvements and enhancements will then rolled into the Unbreakable Enterprise Kernel, which is the key ingredient that sets Oracle Linux apart from other distributions. We also have a number of ongoing projects which are making good progress, and I'm sure you'll hear more about this at the upcoming OpenWorld conference :) Keith Larson: What is something that more people should be aware of when it comes to Oracle Linux and MySQL ?Lenz Grimmer: Many people assume that Oracle Linux is just tuned for Oracle products, such as the Oracle Database or our Engineered Systems. While it's of course true that we do a lot of testing and optimization for these workloads, Oracle Linux is and will remain a general-purpose Linux distribution that is a very good foundation for setting up a LAMP-Stack, for example. We also provide MySQL RPM packages for Oracle Linux, so you can easily stay up to date if you need something newer than what's included in the stock distribution.One more thing that is really unique to Oracle Linux is Ksplice, which allows you to apply security patches to the running Linux kernel, without having to reboot. This ensures that your MySQL database server keeps up and running and is not affected by any downtime. Keith Larson: What else would you like to add ?Lenz Grimmer: Thanks again for getting in touch with me, I appreciated the opportunity. I'm looking forward to MySQL Connect and Oracle OpenWorld and to meet you and many other people from the MySQL community that I haven't seen for quite some time! Keith Larson:  Thank you Lenz!

  Read the article

• Software Architecture: Quality Attributes

  Quality is what all software engineers should strive for when building a new system or adding new functionality. Dictonary.com ambiguously defines quality as a grade of excellence. Unfortunately, quality must be defined within the context of a situation in that each engineer must extract quality attributes from a project’s requirements. Because quality is defined by project requirements the meaning of quality is constantly changing base on the project. Software architecture factors that indicate the relevance and effectiveness The relevance and effectiveness of architecture can vary based on the context in which it was conceived and the quality attributes that are required to meet. Typically when evaluating architecture for a specific system regarding relevance and effectiveness the following questions should be asked.   Architectural relevance and effectiveness questions: Does the architectural concept meet the needs of the system for which it was designed? Out of the competing architectures for a system, which one is the most suitable? If we look at the first question regarding meeting the needs of a system for which it was designed. A system that answers yes to this question must meet all of its quality goals. This means that it consistently meets or exceeds performance goals for the system. In addition, the system meets all the other required system attributers based on the systems requirements. The suitability of a system is based on several factors. In order for a project to be suitable the necessary resources must be available to complete the task. Standard Project Resources: Money Trained Staff Time Life cycle factors that affect the system and design The development life cycle used on a project can drastically affect how a system’s architecture is created as well as influence its design. In the case of using the software development life cycle (SDLC) each phase must be completed before the next can begin.  This waterfall approach does not allow for changes in a system’s architecture after that phase is completed. This can lead to major system issues when the architecture for the system is not as optimal because of missed quality attributes. This can occur when a project has poor requirements and makes misguided architectural decisions to name a few examples. Once the architectural phase is complete the concepts established in this phase must move on to the design phase that is bound to use the concepts and guidelines defined in the previous phase regardless of any missing quality attributes needed for the project. If any issues arise during this phase regarding the selected architectural concepts they cannot be corrected during the current project. This directly has an effect on the design of a system because the proper qualities required for the project where not used when the architectural concepts were approved. When this is identified nothing can be done to fix the architectural issues and system design must use the existing architectural concepts regardless of its missing quality properties because the architectural concepts for the project cannot be altered. The decisions made in the design phase then preceded to fall down to the implementation phase where the actual system is coded based on the approved architectural concepts established in the architecture phase regardless of its architectural quality. Conversely projects using more of an iterative or agile methodology to implement a system has more flexibility to correct architectural decisions based on missing quality attributes. This is due to each phase of the SDLC is executed more than once so any issues identified in architecture of a system can be corrected in the next architectural phase. Subsequently the corresponding changes will then be adjusted in the following design phase so that when the project is completed the optimal architectural and design decision are applied to the solution. Architecture factors that indicate functional suitability Systems that have function shortcomings do not have the proper functionality based on the project’s driving quality attributes. What this means in English is that the system does not live up to what is required of it by the stakeholders as identified by the missing quality attributes and requirements. One way to prevent functional shortcomings is to test the project’s architecture, design, and implementation against the project’s driving quality attributes to ensure that none of the attributes were missed in any of the phases. Another way to ensure a system has functional suitability is to certify that all its requirements are fully articulated so that there is no chance for misconceptions or misinterpretations by all stakeholders. This will help prevent any issues regarding interpreting the system requirements during the initial architectural concept phase, design phase and implementation phase. Consider the applicability of other architectural models When considering an architectural model for a project is also important to consider other alternative architectural models to ensure that the model that is selected will meet the systems required functionality and high quality attributes. Recently I can remember talking about a project that I was working on and a coworker suggested a different architectural approach that I had never considered. This new model will allow for the same functionally that is offered by the existing model but will allow for a higher quality project because it fulfills more quality attributes. It is always important to seek alternatives prior to committing to an architectural model. Factors used to identify high-risk components A high risk component can be defined as a component that fulfills 2 or more quality attributes for a system. An example of this can be seen in a web application that utilizes a remote database. One high-risk component in this system is the TCIP component because it allows for HTTP connections to handle by a web server and as well as allows for the server to also connect to a remote database server so that it can import data into the system. This component allows for the assurance of data quality attribute and the accessibility quality attribute because the system is available on the network. If for some reason the TCIP component was to fail the web application would fail on two quality attributes accessibility and data assurance in that the web site is not accessible and data cannot be update as needed. Summary As stated previously, quality is what all software engineers should strive for when building a new system or adding new functionality. The quality of a system can be directly determined by how closely it is implemented when compared to its desired quality attributes. One way to insure a higher quality system is to enforce that all project requirements are fully articulated so that no assumptions or misunderstandings can be made by any of the stakeholders. By doing this a system has a better chance of becoming a high quality system based on its quality attributes

  Read the article

• Built-in card-reader doesn't work. HP Compaq nx6325 notebook

  - by user10940

  I have a HP-Compaq nx6325 notebook with an built-in card-reader (SD, MS/Pro, MMC, SM, XD) and the ubuntu (10.10.) don't see it. I've tried to install it manually, with this steps (and with this tifmxx driver), but doesn't work. The compile log: $ echo /home/tvera/downloads/cr_install /home/tvera/downloads/cr_install $ make -C /lib/modules/2.6.35-25-generic/build M=/home/tvera/downloads/cr_install make[1]: Entering directory `/usr/src/linux-headers-2.6.35-25-generic' CC [M] /home/tvera/downloads/cr_install/tifm_core.o In file included from /home/tvera/downloads/cr_install/tifm_core.c:12: /home/tvera/downloads/cr_install/linux/tifm.h:128: error: field ‘cdev’ has incomplete type /home/tvera/downloads/cr_install/tifm_core.c: In function ‘tifm_uevent’: /home/tvera/downloads/cr_install/tifm_core.c:69: warning: passing argument 1 of ‘add_uevent_var’ from incompatible pointer type include/linux/kobject.h:244: note: expected ‘struct kobj_uevent_env *’ but argument is of type ‘char **’ /home/tvera/downloads/cr_install/tifm_core.c:69: warning: passing argument 2 of ‘add_uevent_var’ makes pointer from integer without a cast include/linux/kobject.h:244: note: expected ‘const char *’ but argument is of type ‘int’ /home/tvera/downloads/cr_install/tifm_core.c: At top level: /home/tvera/downloads/cr_install/tifm_core.c:161: warning: initialization from incompatible pointer type /home/tvera/downloads/cr_install/tifm_core.c: In function ‘tifm_free’: /home/tvera/downloads/cr_install/tifm_core.c:170: warning: type defaults to ‘int’ in declaration of ‘__mptr’ /home/tvera/downloads/cr_install/tifm_core.c:170: warning: initialization from incompatible pointer type /home/tvera/downloads/cr_install/tifm_core.c: At top level: /home/tvera/downloads/cr_install/tifm_core.c:177: error: unknown field ‘release’ specified in initializer /home/tvera/downloads/cr_install/tifm_core.c:178: warning: initialization from incompatible pointer type /home/tvera/downloads/cr_install/tifm_core.c: In function ‘tifm_alloc_adapter’: /home/tvera/downloads/cr_install/tifm_core.c:190: error: implicit declaration of function ‘class_device_initialize’ /home/tvera/downloads/cr_install/tifm_core.c: In function ‘tifm_add_adapter’: /home/tvera/downloads/cr_install/tifm_core.c:211: error: ‘BUS_ID_SIZE’ undeclared (first use in this function) /home/tvera/downloads/cr_install/tifm_core.c:211: error: (Each undeclared identifier is reported only once /home/tvera/downloads/cr_install/tifm_core.c:211: error: for each function it appears in.) /home/tvera/downloads/cr_install/tifm_core.c:212: error: implicit declaration of function ‘class_device_add’ /home/tvera/downloads/cr_install/tifm_core.c: In function ‘tifm_remove_adapter’: /home/tvera/downloads/cr_install/tifm_core.c:237: error: implicit declaration of function ‘class_device_del’ /home/tvera/downloads/cr_install/tifm_core.c: In function ‘tifm_free_adapter’: /home/tvera/downloads/cr_install/tifm_core.c:243: error: implicit declaration of function ‘class_device_put’ /home/tvera/downloads/cr_install/tifm_core.c: In function ‘tifm_alloc_device’: /home/tvera/downloads/cr_install/tifm_core.c:275: error: ‘struct device’ has no member named ‘bus_id’ /home/tvera/downloads/cr_install/tifm_core.c:275: error: ‘BUS_ID_SIZE’ undeclared (first use in this function) make[2]: *** [/home/tvera/downloads/cr_install/tifm_core.o] Error 1 make[1]: *** [_module_/home/tvera/downloads/cr_install] Error 2 make[1]: Leaving directory `/usr/src/linux-headers-2.6.35-25-generic' make: *** [all] Error 2 The output of lsusb: Bus 001 Device 005: ID 05e3:0702 Genesys Logic, Inc. USB 2.0 IDE Adapter Bus 003 Device 003: ID 0458:003a KYE Systems Corp. (Mouse Systems) NetScroll+ Mini Traveler Bus 003 Device 002: ID 08ff:2580 AuthenTec, Inc. AES2501 Fingerprint Sensor Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

  Read the article

• Company Review: Google Products

  Google, Inc offers an array of products and services to all of its end-users. However their search capabilities are the foundation for Google’s current success and their primary business focus. Currently, Google offers over twenty different search applications that allow users to search the internet for books, maps, videos, images, products and much more. Their product decisions have allowed users demands to be met while focusing on the free based model. This allows users to access Google data free of charge and indirectly gives Google a strong competitive advantage of other competitors along with the accuracy of the search results. According to Google, Inc, they offer the following types of searching capabilities: Alerts Get email updates on the topics of your choice Blog Search Find blogs on your favorite topics  Books Search the full text of books  Custom Search Create a customized search experience for your community  Desktop Search and personalize your computer  Dictionary Search for definitions of words and phrases Directory Search the web, organized by topic or category Earth Explore the world from your computer Finance Business info, news and interactive charts GOOG-411 Find and connect for free with businesses from your phone  Images Search for images on the web Maps View maps and directions News Search thousands of news stories Patent Search Search the full text of US Patents Product Search Search for stuff to buy Scholar Search scholarly papers Toolbar Add a search box to your browser Trends Explore past and present search trends Videos Search for videos on the web Web Search Search billions of web pages Web Search Features Find movies, music, stocks, books and more mapping Google’s free based business model is only one way it differentiates itself from its competition. There is also a strong focus on the accuracy of search results and the speed in which they are returned to the end-user. Quality function deployment (QFD) is a structured method used to help connect user needs to the design features of a project proposed to address those needs. This method is particularly useful in accounting for needs that are not easily articulated or precisely defined according to the U. S. Department of Transportation Federal Highway Administration. Due to the fact that QFD is so customer driven Google is always in a constant state of change in attempt to reengineer its search algorithms, and other dependant systems so that end-users requirements are constantly being met. Value engineering is a key example of this, Google is constantly trying to improve all aspects of its products, improve system maintainability, and system interoperability. Bridgefield Group defines value engineering as an organized methodology that identifies and selects the lowest lifecycle cost options in design, materials and processes that achieves the desired level of performance, reliability and customer satisfaction. In addition, it seeks to remove unnecessary costs in the above areas and is often a joint effort with cross-functional internal teams and relevant suppliers. Common issues that appear when developing large scale systems like Google’s search applications include modular design of a product and/or service and providing accurate value analysis. A design approach that adheres to four fundamental tenets of cohesiveness, encapsulation, self-containment, and high binding to design a system component as an independently operable unit subject to change is how the Open System Joint Task Force defines modular design. More specifically M. S. Schmaltz defines modular software design as having a large collection of statements strung together in one partition of in-line code; we segment or divide the statements into logical groups called modules. Each module performs one or two tasks, and then passes control to another module. By breaking up the code into "bite-sized chunks", so to speak, we are able to better control the flow of data and control. This is especially true in large software systems. Value analysis is a process to evaluate products and services based on effectiveness, safety, and cost. Value analysis involves assessing the quality as well as the cost of a product or service as defined by the Healthcare Financial Management Association.  “Operations Management deals with the design and management of products, processes, services and supply chains. It considers the acquisition, development, and utilization of resources that firms need to deliver the goods and services their clients want.” (MIT,2010) Google, Inc encourages an open environment between all employees, also known as Googlers. This is reinforced by a cross-section team or cross-functional teams comprised from multiple departments assigned to every project so that every department like marketing, finance, and quality assurance has input on every project. In addition, Google is known for their openness to new ideas regardless of the status or seniority of an employee. In fact, Google allows for 20% of an employee’s time can be devoted to developing new ideas and/or pet projects. HumTech.com defines a cross-functional team as a collection of people with varied levels of skills and experience brought together to accomplish a task. As the name implies, Cross-Functional Team members come from different organizational units. Cross-Functional Teams may be permanent or ad hoc. Google’s search application product strategy primarily focuses on mass customization. This is allows Google to create a base search application and allows results to be returned to the end-users quickly based on specific parameters and search settings. In addition, they also store the data that is returned in case other desire the same results based on other end-users supplying the same customized settings. This allows Google to appear to render search results in virtually real-time to the user while allowing for complete customization of the searching criteria. Greg Vogl, a professor at Uganda Martyrs University, defines mass customization as when a business gives its customers the opportunity to tailor its products or services to the customer's specifications. The IT staff at Google play a key role in ensuring that the search application’s product strategy is maintained simply because the IT staff designs, develops, and maintains all of their proprietary applications. In fact, they also maintain all network infrastructure to ensure that it is available to all end-users. References: http://www.google.com/intl/en/options/ http://ops.fhwa.dot.gov/freight/publications/ftat_user_guide/sec5.htm http://www.bridgefieldgroup.com/bridgefieldgroup/glos9.htm#V http://www.acq.osd.mil/osjtf/termsdef.html http://www.cise.ufl.edu/~mssz/Pascal-CGS2462/prog-dsn.html http://www.hfma.org/publications/business_caring_newsletter/exclusives/Supply+and+Inventory+Terms+Defined.htm http://mitsloan.mit.edu/omg/om-definition.php http://www.humtech.com/opm/grtl/ols/ols3.cfm http://www.gregvogl.net/courses/mis1/glossary.htm

  Read the article

< Previous Page | 73 74 75 76 77 78 79 80 81 82 83 84  | Next Page >