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  • 2 Days of Share &amp; Point

    - by Mark Rackley
    Groovy man… SharePoint Saturday Ozarks is back for 2010, bigger and better than before. Join us for a far out time and learn more about SharePoint in one day than you could in a year from the man… Yes! SharePoint Saturday Ozarks is back! SharePoint Saturday Ozarks is the largest SharePoint conference in Arkansas, Southern Missouri, and the very north east tip of Oklahoma. Last year we had a great turn out with 20 speakers, 5 MVPs, and attendees coming from Arkansas, Texas, Oklahoma, Missouri, Kansas, Nebraska, Indiana, Ohio, Alabama, Michigan, and Washington. Hey Man… what’s SharePoint Saturday anyway? Sounds like a conspiracy man… Not to worry, SharePoint Saturday is not an arm of the government bent on mind control or any attempt what-so-ever to bring you down man. SharePoint Saturday is grass roots effort started by Michael Lotter (http://www.sharepointsaturday.org/pages/about.aspx). It is a FREE one day event where the best SharePoint speakers gather to present their love, hatred, and frustrations of SharePoint to those lucky individuals who attend. Lessons are learned, contacts are made, prizes are won, food is eaten, assorted beverages are consumed until wee hours of the morning. SharePoint Saturday started with just a few sporadic one day events here and there. However, over the past year SharePoint Saturday has exploded and it’s hard to find a weekend where there is NOT a SharePoint Saturday event happing in some corner of the globe. There are even occasions where there are two SharePoint Saturdays on the same day! Many people are pleasantly surprised at the caliber of speakers at these SharePoint Saturday events. For the most part, these speakers are more eloquent, practiced, and practical than those speakers you find at the major multi-day conferences. These guys aren’t even paid to speak.. they do it out of love man… SharePoint Saturday Ozarks 2009 Alumni We had a star studded cast last year with many returning this year! Just check out the fun that they had… John Ferringer – Admin rockstar… I can still sense the awesomeness   SharePoint poster children Mike Watson & Laura Rogers     Lori Gowin spreading the SharePoint Love Eric Shupps is a little bit country and a little bit rock and roll       Cathy Dew, Sean McDonough, and JD Wade relaxing between gigs Actually, you can see real photos from last year’s SharePoint Saturday ozarks here:  picasaweb.google.com/mrackley/SharePointSaturdayOzarks#    What’s new for SharePoint Saturday Ozarks 2010 SharePoint Saturday Ozarks 2010 will totally blow your mind man. We’re getting the band back to together with many returning speakers and few new faces. Joel Oleson will be speaking this year, maybe he’ll grace us with his song stylings. Sadly, once again, Andrew Connell will not be able to attend SharePoint Saturday Ozarks, however he did feel the need to show his support in his own way. Prizes this year currently include books, software, a Zune HD, and much more! Wait Man… You said 2 days? I thought it was a one day event? Correct you are my herbal smelling friend… SharePoint Saturday Ozarks 2010 will spread the love an additional day this year. The first day will be all about the SharePoint love, on day 2 we will be taking a leisurely float down the Buffalo National River for those interested in a truly unique experience (no banjos allowed please).   Here are the details: WHAT 4 – 5 hour float down the Buffalo National River WHEN & WHERE Sunday June 13th. We will be leaving at 10am from the Parking Lot of: Gordon’s Motel & Canoe Rental Old Highway 7 Jasper, AR 72641 (870) 446-5252 Jasper is about 30 minutes south of Harrison, AR on Highway 7 South. You are responsible for bumming a ride to/from Gordon’s Motel, but they will be shuttling us to/from the river and providing canoes and a boxed lunch. WHAT ELSE? The float trip is dependent on the weather of course, we won’t be floating down the river in a thunderstorm, however I planned SPS Ozarks around a time of year ideal for floating. We aren’t talking class 5 rapids here, you don’t need any real skill, but you need to be okay with possibly tipping your canoe over once or twice. You can bring your own assorted beverages with you, but glass containers are not allowed on the river. I suggest a small cooler with extra snacks and drinks. Also bring clothing you can get wet in (these SharePoint people can get ornery). HOW DO I SIGN UP? When you register for SharePoint Saturday Ozarks, you will have the option to also sign up for the float trip. Seats are limited though! If you do not intend to go, please do not take someone else’s place.  The cost for the float trip will be about $35 dollars per person (which you are responsible for unless we find a sponsor). The price includes shuttle to/from river, canoe, life jackets, paddles, and boxed lunch. Far out man… how do I register??? You can register for SharePoint Saturday Ozarks by going to http://spsozarks.eventbrite.com/ We are limited to 200 people for the conference and 50 people for the float trip, so register today before we are sold out. Lodging for SharePoint Saturday Ozarks will once again take place at the Hotel Seville: Annex Suites are available for $103.20 This is So Groovy.. How can I help? I’m glad you asked! We are still looking for a few sponsors and one or two more speakers. If you are interested please let me know!  You can find out more information at http://www.sharepointsaturday.org/ozarks Hey… wait a minute…. what exactly IS SharePoint man??? Come to SharePoint Saturday Ozarks and find out!!  See you guys there!

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  • Beginner&amp;#8217;s Guide to Git

    <b>Make Tech Easier:</b> "Git is the revision control system created by the Linux kernel&#8217;s famous Linus Torvalds due to a lack of satisfaction with existing solutions. The main emphasis in the design was on speed, or more specifically, efficiency."

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  • array and array_view from amp.h

    - by Daniel Moth
    This is a very long post, but it also covers what are probably the classes (well, array_view at least) that you will use the most with C++ AMP, so I hope you enjoy it! Overview The concurrency::array and concurrency::array_view template classes represent multi-dimensional data of type T, of N dimensions, specified at compile time (and you can later access the number of dimensions via the rank property). If N is not specified, it is assumed that it is 1 (i.e. single-dimensional case). They are rectangular (not jagged). The difference between them is that array is a container of data, whereas array_view is a wrapper of a container of data. So in that respect, array behaves like an STL container, whereas the closest thing an array_view behaves like is an STL iterator (albeit with random access and allowing you to view more than one element at a time!). The data in the array (whether provided at creation time or added later) resides on an accelerator (which is specified at creation time either explicitly by the developer, or set to the default accelerator at creation time by the runtime) and is laid out contiguously in memory. The data provided to the array_view is not stored by/in the array_view, because the array_view is simply a view over the real source (which can reside on the CPU or other accelerator). The underlying data is copied on demand to wherever the array_view is accessed. Elements which differ by one in the least significant dimension of the array_view are adjacent in memory. array objects must be captured by reference into the lambda you pass to the parallel_for_each call, whereas array_view objects must be captured by value (into the lambda you pass to the parallel_for_each call). Creating array and array_view objects and relevant properties You can create array_view objects from other array_view objects of the same rank and element type (shallow copy, also possible via assignment operator) so they point to the same underlying data, and you can also create array_view objects over array objects of the same rank and element type e.g.   array_view<int,3> a(b); // b can be another array or array_view of ints with rank=3 Note: Unlike the constructors above which can be called anywhere, the ones in the rest of this section can only be called from CPU code. You can create array objects from other array objects of the same rank and element type (copy and move constructors) and from other array_view objects, e.g.   array<float,2> a(b); // b can be another array or array_view of floats with rank=2 To create an array from scratch, you need to at least specify an extent object, e.g. array<int,3> a(myExtent);. Note that instead of an explicit extent object, there are convenience overloads when N<=3 so you can specify 1-, 2-, 3- integers (dependent on the array's rank) and thus have the extent created for you under the covers. At any point, you can access the array's extent thought the extent property. The exact same thing applies to array_view (extent as constructor parameters, incl. convenience overloads, and property). While passing only an extent object to create an array is enough (it means that the array will be written to later), it is not enough for the array_view case which must always wrap over some other container (on which it relies for storage space and actual content). So in addition to the extent object (that describes the shape you'd like to be viewing/accessing that data through), to create an array_view from another container (e.g. std::vector) you must pass in the container itself (which must expose .data() and a .size() methods, e.g. like std::array does), e.g.   array_view<int,2> aaa(myExtent, myContainerOfInts); Similarly, you can create an array_view from a raw pointer of data plus an extent object. Back to the array case, to optionally initialize the array with data, you can pass an iterator pointing to the start (and optionally one pointing to the end of the source container) e.g.   array<double,1> a(5, myVector.begin(), myVector.end()); We saw that arrays are bound to an accelerator at creation time, so in case you don’t want the C++ AMP runtime to assign the array to the default accelerator, all array constructors have overloads that let you pass an accelerator_view object, which you can later access via the accelerator_view property. Note that at the point of initializing an array with data, a synchronous copy of the data takes place to the accelerator, and then to copy any data back we'll see that an explicit copy call is required. This does not happen with the array_view where copying is on demand... refresh and synchronize on array_view Note that in the previous section on constructors, unlike the array case, there was no overload that accepted an accelerator_view for array_view. That is because the array_view is simply a wrapper, so the allocation of the data has already taken place before you created the array_view. When you capture an array_view variable in your call to parallel_for_each, the copy of data between the non-CPU accelerator and the CPU takes place on demand (i.e. it is implicit, versus the explicit copy that has to happen with the array). There are some subtleties to the on-demand-copying that we cover next. The assumption when using an array_view is that you will continue to access the data through the array_view, and not through the original underlying source, e.g. the pointer to the data that you passed to the array_view's constructor. So if you modify the data through the array_view on the GPU, the original pointer on the CPU will not "know" that, unless one of two things happen: you access the data through the array_view on the CPU side, i.e. using indexing that we cover below you explicitly call the array_view's synchronize method on the CPU (this also gets called in the array_view's destructor for you) Conversely, if you make a change to the underlying data through the original source (e.g. the pointer), the array_view will not "know" about those changes, unless you call its refresh method. Finally, note that if you create an array_view of const T, then the data is copied to the accelerator on demand, but it does not get copied back, e.g.   array_view<const double, 5> myArrView(…); // myArrView will not get copied back from GPU There is also a similar mechanism to achieve the reverse, i.e. not to copy the data of an array_view to the GPU. copy_to, data, and global copy/copy_async functions Both array and array_view expose two copy_to overloads that allow copying them to another array, or to another array_view, and these operations can also be achieved with assignment (via the = operator overloads). Also both array and array_view expose a data method, to get a raw pointer to the underlying data of the array or array_view, e.g. float* f = myArr.data();. Note that for array_view, this only works when the rank is equal to 1, due to the data only being contiguous in one dimension as covered in the overview section. Finally, there are a bunch of global concurrency::copy functions returning void (and corresponding concurrency::copy_async functions returning a future) that allow copying between arrays and array_views and iterators etc. Just browse intellisense or amp.h directly for the full set. Note that for array, all copying described throughout this post is deep copying, as per other STL container expectations. You can never have two arrays point to the same data. indexing into array and array_view plus projection Reading or writing data elements of an array is only legal when the code executes on the same accelerator as where the array was bound to. In the array_view case, you can read/write on any accelerator, not just the one where the original data resides, and the data gets copied for you on demand. In both cases, the way you read and write individual elements is via indexing as described next. To access (or set the value of) an element, you can index into it by passing it an index object via the subscript operator. Furthermore, if the rank is 3 or less, you can use the function ( ) operator to pass integer values instead of having to use an index object. e.g. array<float,2> arr(someExtent, someIterator); //or array_view<float,2> arr(someExtent, someContainer); index<2> idx(5,4); float f1 = arr[idx]; float f2 = arr(5,4); //f2 ==f1 //and the reverse for assigning, e.g. arr(idx[0], 7) = 6.9; Note that for both array and array_view, regardless of rank, you can also pass a single integer to the subscript operator which results in a projection of the data, and (for both array and array_view) you get back an array_view of rank N-1 (or if the rank was 1, you get back just the element at that location). Not Covered In this already very long post, I am not going to cover three very cool methods (and related overloads) that both array and array_view expose: view_as, section, reinterpret_as. We'll revisit those at some point in the future, probably on the team blog. Comments about this post by Daniel Moth welcome at the original blog.

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  • simplejson double escapes data causing invalid JSON string

    - by mike_hornbeck
    I have a simple form for managing manufacturers in my shop. After posting form, ajax call returns json with updated data to the form. Problem is, that the returned string is invalid. It looks like it was double-escaped. Strangely similar approach across the whole shop works without any problems. I'm also using jquery 1.6 as javascript framework. Model contains of 3 fields : char for name, text for description and image field for manufacturer logo. The function : def update_data(request, manufacturer_id): """Updates data of manufacturer with given manufacturer id. """ manufacturer = Manufacturer.objects.get(pk=manufacturer_id) form = ManufacturerDataForm(request.FILES, request.POST, instance=manufacturer) if form.is_valid(): form.save() msg = _(u"Manufacturer data has been saved.") html = [ ["#data", manufacturer_data_inline(request, manufacturer_id, form)], ["#selectable-factories-inline", selectable_manufacturers_inline(request, manufacturer_id)], ] result = simplejson.dumps({ "html": html }, cls=LazyEncoder) return HttpResponse(result) The error in console : error with invalid JSON : uncaught exception: Invalid JSON: {"html": [["#data", "\n<h2>Dane</h2>\n<div class="\&quot;manufacturer-image\&quot;">\n \n</div>\n<form action="\&quot;/manage/update-manufacturer-data/1\&quot;" method="\&quot;post\&quot;">\n \n <div class="\&quot;field\&quot;">\n <div class="\&quot;label\&quot;">\n <label for="\&quot;id_name\&quot;">Nazwa</label>:\n </div>\n \n \n <div class="\&quot;error\&quot;">\n <input id="\&quot;id_name\&quot;" name="\&quot;name\&quot;" maxlength="\&quot;50\&quot;" type="\&quot;text\&quot;">\n <ul class="\&quot;errorlist\&quot;"><li>Pole wymagane</li></ul>\n </div>\n \n </div>\n\n <div class="\&quot;field\&quot;">\n <div class="\&quot;label\&quot;">\n <label for="\&quot;id_image\&quot;">Zdjecie</label>:\n </div>\n \n \n <div>\n <input name="\&quot;image\&quot;" id="\&quot;id_image\&quot;" type="\&quot;file\&quot;">\n </div>\n \n </div>\n\n <div class="\&quot;field\&quot;">\n <div class="\&quot;label\&quot;">\n <label for="\&quot;id_description\&quot;">Opis</label>:\n </div>\n \n \n <div>\n <textarea id="\&quot;id_description\&quot;" rows="\&quot;10\&quot;" cols="\&quot;40\&quot;" name="\&quot;description\&quot;"></textarea>\n </div>\n \n </div>\n \n <div class="\&quot;buttons\&quot;">\n <input class="\&quot;ajax-save-button" button\"="" type="\&quot;submit\&quot;">\n </div>\n</form>"], ["#selectable-factories-inline", "\n <div>\n <a class="\&quot;selectable" selected\"\n="" href="%5C%22/manage/manufacturer/1%5C%22">\n L1\n </a>\n </div>\n\n <div>\n <a class="\&quot;selectable" \"\n="" href="%5C%22/manage/manufacturer/4%5C%22">\n KR3W\n </a>\n </div>\n\n <div>\n <a class="\&quot;selectable" \"\n="" href="%5C%22/manage/manufacturer/3%5C%22">\n L1TA\n </a>\n </div>\n\n"]]} Any ideas ?

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  • C++ AMP recording and slides

    - by Daniel Moth
    Yesterday we announced C++ Accelerated Massive Parallelism. Many of you want to know more about the API instead of just meta information. I will trickle more code over the coming months leading up to the date when we will share actual bits. Until you have bits in your hand, it is only your curiosity that is blocked, so I ask you to be patient with that and allow me to release this on our own schedule ;-) You can now watch my 45-minute session introducing C++ AMP on channel9. You will also want to download the slides (pdf), because they are not readable in the recording. Comments about this post welcome at the original blog.

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  • Direct3D - Zooming into Mouse Position

    - by roohan
    I'm trying to implement my camera class for a simulation. But I cant figure out how to zoom into my world based on the mouse position. I mean the object under the mouse cursor should remain at the same screen position. My zooming looks like this: VOID ZoomIn(D3DXMATRIX& WorldMatrix, FLOAT const& MouseX, FLOAT const& MouseY) { this->Position.z = this->Position.z * 0.9f; D3DXMatrixLookAtLH(&this->ViewMatrix, &this->Position, &this->Target, &this->UpDirection); } I passed the world matrix to the function because I had the idea to move my drawing origin according to the mouse position. But I cant find out how to calculate the offset in to move my drawing origin. Anyone got an idea how to calculate this? Thanks in advance. SOLVED Ok I solved my problem. Here is the code if anyone is interested: VOID CAMERA2D::ZoomIn(FLOAT const& MouseX, FLOAT const& MouseY) { // Get the setting of the current view port. D3DVIEWPORT9 ViewPort; this->Direct3DDevice->GetViewport(&ViewPort); // Convert the screen coordinates of the mouse to world space coordinates. D3DXVECTOR3 VectorOne; D3DXVECTOR3 VectorTwo; D3DXVec3Unproject(&VectorOne, &D3DXVECTOR3(MouseX, MouseY, 0.0f), &ViewPort, &this->ProjectionMatrix, &this->ViewMatrix, &WorldMatrix); D3DXVec3Unproject(&VectorTwo, &D3DXVECTOR3(MouseX, MouseY, 1.0f), &ViewPort, &this->ProjectionMatrix, &this->ViewMatrix, &WorldMatrix); // Calculate the resulting vector components. float WorldZ = 0.0f; float WorldX = ((WorldZ - VectorOne.z) * (VectorTwo.x - VectorOne.x)) / (VectorTwo.z - VectorOne.z) + VectorOne.x; float WorldY = ((WorldZ - VectorOne.z) * (VectorTwo.y - VectorOne.y)) / (VectorTwo.z - VectorOne.z) + VectorOne.y; // Move the camera into the screen. this->Position.z = this->Position.z * 0.9f; D3DXMatrixLookAtLH(&this->ViewMatrix, &this->Position, &this->Target, &this->UpDirection); // Calculate the world space vector again based on the new view matrix, D3DXVec3Unproject(&VectorOne, &D3DXVECTOR3(MouseX, MouseY, 0.0f), &ViewPort, &this->ProjectionMatrix, &this->ViewMatrix, &WorldMatrix); D3DXVec3Unproject(&VectorTwo, &D3DXVECTOR3(MouseX, MouseY, 1.0f), &ViewPort, &this->ProjectionMatrix, &this->ViewMatrix, &WorldMatrix); // Calculate the resulting vector components. float WorldZ2 = 0.0f; float WorldX2 = ((WorldZ2 - VectorOne.z) * (VectorTwo.x - VectorOne.x)) / (VectorTwo.z - VectorOne.z) + VectorOne.x; float WorldY2 = ((WorldZ2 - VectorOne.z) * (VectorTwo.y - VectorOne.y)) / (VectorTwo.z - VectorOne.z) + VectorOne.y; // Create a temporary translation matrix for calculating the origin offset. D3DXMATRIX TranslationMatrix; D3DXMatrixIdentity(&TranslationMatrix); // Calculate the origin offset. D3DXMatrixTranslation(&TranslationMatrix, WorldX2 - WorldX, WorldY2 - WorldY, 0.0f); // At the offset to the cameras world matrix. this->WorldMatrix = this->WorldMatrix * TranslationMatrix; } Maybe someone has even a better solution than mine.

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  • Opening of the spWeb.ContentTypes gives SOAP Exception 0x80004004

    - by mdi
    Hi everybody! I have the code which going through the sharepoint contenttypes and changes needed field display names. On my local server everything works fine, but on the client side it gives me an error: Microsoft.SharePoint.SPException: Operation aborted (Exception from HRESULT: 0x80004004 (E_ABORT)) --- System.Runtime.InteropServices.COMException (0x80004004): Operation aborted (Exception from HRESULT: 0x80004004 (E_ABORT)) at Microsoft.SharePoint.Library.SPRequestInternalClass.OpenWebInternal(String bstrUrl, Guid& pguidID, String& pbstrRequestAccessEmail, UInt32& pwebVersion, String& pbstrServerRelativeUrl, UInt32& pnLanguage, UInt32& pnLocale, String& pbstrDefaultTheme, String& pbstrDefaultThemeCSSUrl, String& pbstrAlternateCSSUrl, String& pbstrCustomizedCssFileList, String& pbstrCustomJSUrl, String& pbstrAlternateHeaderUrl, String& pbstrMasterUrl, String& pbstrCustomMasterUrl, String& pbstrSiteLogoUrl, String& pbstrSiteLogoDescription, Object& pvarUser, Boolean& pvarIsAuditor, Int32& plSiteFlags) at Microsoft.SharePoint.Library.SPRequest.OpenWebInternal(String bstrUrl, Guid& pguidID, String& pbstrRequestAccessEmail, UInt32& pwebVersion, String& pbstrServerRelativeUrl, UInt32& pnLanguage, UInt32& pnLocale, String& pbstrDefaultTheme, String& pbstrDefaultThemeCSSUrl, String& pbstrAlternateCSSUrl, String& pbstrCustomizedCssFileList, String& pbstrCustomJSUrl, String& pbstrAlternateHeaderUrl, String& pbstrMasterUrl, String& pbstrCustomMasterUrl, String& pbstrSiteLogoUrl, String& pbstrSiteLogoDescription, Object& pvarUser, Boolean& pvarIsAuditor, Int32& plSiteFlags) --- End of inner exception stack trace --- at Microsoft.SharePoint.Library.SPRequest.OpenWebInternal(String bstrUrl, Guid& pguidID, String& pbstrRequestAccessEmail, UInt32& pwebVersion, String& pbstrServerRelativeUrl, UInt32& pnLanguage, UInt32& pnLocale, String& pbstrDefaultTheme, String& pbstrDefaultThemeCSSUrl, String& pbstrAlternateCSSUrl, String& pbstrCustomizedCssFileList, String& pbstrCustomJSUrl, String& pbstrAlternateHeaderUrl, String& pbstrMasterUrl, String& pbstrCustomMasterUrl, String& pbstrSiteLogoUrl, String& pbstrSiteLogoDescription, Object& pvarUser, Boolean& pvarIsAuditor, Int32& plSiteFlags) at Microsoft.SharePoint.SPWeb.InitWebPublic() at Microsoft.SharePoint.SPWeb.get_ServerRelativeUrl() at Microsoft.SharePoint.SPWeb.get_Url() at Microsoft.SharePoint.SPContentTypeCollection.FetchCollection() at Microsoft.SharePoint.SPContentTypeCollection..ctor(SPWeb web, Boolean bAll) at Microsoft.SharePoint.SPWeb.get_ContentTypes() the code is below: SPWebApplication webApp = SPWebService.ContentService.WebApplications[someGuid]; foreach (SPSite spSite in webApp.Sites) { using (SPWeb spWeb = spSite.RootWeb) { try { foreach (SPContentType spContentType in spWeb.ContentTypes) { ... }}}.. Could anybody provide me with workaround or with the reason of the problem.

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  • Entity Framework &amp; Transactions

    - by Sudheer Kumar
    There are many instances we might have to use transactions to maintain data consistency. With Entity Framework, it is a little different conceptually. Case 1 – Transaction b/w multiple SaveChanges(): here if you just use a transaction scope, then Entity Framework (EF) will use distributed transactions instead of local transactions. The reason is that, EF closes and opens the connection when ever required only, which means, it used 2 different connections for different SaveChanges() calls. To resolve this, use the following method. Here we are opening a connection explicitly so as not to span across multipel connections.   using (TransactionScope ts = new TransactionScope()) {     context.Connection.Open();     //Operation1 : context.SaveChanges();     //Operation2 :  context.SaveChanges()     //At the end close the connection     ts.Complete(); } catch (Exception ex) {       //Handle Exception } finally {       if (context.Connection.State == ConnectionState.Open)       {            context.Connection.Close();       } }   Case 2 – Transaction between DB & Non-DB operations: For example, assume that you have a table that keeps track of Emails to be sent. Here you want to update certain details like DataSent once if the mail was successfully sent by the e-mail client. Email eml = GetEmailToSend(); eml.DateSent = DateTime.Now; using (TransactionScope ts = new TransactionScope()) {    //Update DB    context.saveChanges();   //if update is successful, send the email using smtp client   smtpClient.Send();   //if send was successful, then commit   ts.Complete(); }   Here since you are dealing with a single context.SaveChanges(), you just need to use the TransactionScope, just before saving the context only.   Hope this was helpful!

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  • 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.

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  • Sqlite &amp; Entity Framework 4

    - by Dane Morgridge
    I have been working on a few client app projects in my spare time that need to persist small amounts of data and have been looking for an easy to use embedded database.  I really like db4o but I'm not wanting to open source this particular project so it was not an option.  Then I remembered that there was an ADO.NET provider for sqlite.  Being a fan of sqlite in general, I downloaded it and gave it an install.  The installer added tooling support for both Visual Studio 2008 & 2010 which is nice because I am working almost exclusively in 2010 at the moment.  I noticed that the provider also had support for Entity Framework, but not specifically v4.  I created a database using the tools that get installed with Visual Studio and all seemed to work fine.  I went on to create an Entity Framework context and selected the sqlite database and to my surprise it worked with out any problems.  The model showed up just like it would for any database and so I started to write a little code to test and then.. BAM!.. Exception. "Mixed mode assembly is built against version 'v2.0.50727' of the runtime and cannot be loaded in the 4.0 runtime without additional configuration information." A quick bit of searching on Bing found the answer.  To get it working, you need to include the following code in your web.config file: 1: <startup useLegacyV2RuntimeActivationPolicy="true"> 2: <supportedRuntime version="v4.0" /> 3: </startup> And then everything magically works.  Entity Framework 4 features worked, like lazy loading and even the POCO templates worked.  The only thing that didn't work was the model first development.  The SQL generated was for SQL Server and of course wouldn't run on sqlite without some modifications. The only other oddity I found was that in order to have an auto incrementing id, you have to use the full integer data type for sqlite; a regular int won't do the trick.  This translates to an Int64, or a long when working with it in Entity Framework.  Not a big deal, but something you need to be aware of. All in all, I am quite impressed with the Entity Framework support I found with sqlite.  I wasn't really expecting much at all, and I was pleasantly surprised. I downloaded the ADO.NET sqlite provider from http://sqlite.phxsoftware.com/.  If you want to use an embedded database with Entity Framework, give it a look.  It will be well worth your time.

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  • concurrency::extent<N> from amp.h

    - by Daniel Moth
    Overview We saw in a previous post how index<N> represents a point in N-dimensional space and in this post we'll see how to define the N-dimensional space itself. With C++ AMP, an N-dimensional space can be specified with the template class extent<N> where you define the size of each dimension. From a look and feel perspective, you'd expect the programmatic interface of a point type and size type to be similar (even though the concepts are different). Indeed, exactly like index<N>, extent<N> is essentially a coordinate vector of N integers ordered from most- to least- significant, BUT each integer represents the size for that dimension (and hence cannot be negative). So, if you read the description of index, you won't be surprised with the below description of extent<N> There is the rank field returning the value of N you passed as the template parameter. You can construct one extent from another (via the copy constructor or the assignment operator), you can construct it by passing an integer array, or via convenience constructor overloads for 1- 2- and 3- dimension extents. Note that the parameterless constructor creates an extent of the specified rank with all bounds initialized to 0. You can access the components of the extent through the subscript operator (passing it an integer). You can perform some arithmetic operations between extent objects through operator overloading, i.e. ==, !=, +=, -=, +, -. There are operator overloads so that you can perform operations between an extent and an integer: -- (pre- and post- decrement), ++ (pre- and post- increment), %=, *=, /=, +=, –= and, finally, there are additional overloads for plus and minus (+,-) between extent<N> and index<N> objects, returning a new extent object as the result. In addition to the usual suspects, extent offers a contains function that tests if an index is within the bounds of the extent (assuming an origin of zero). It also has a size function that returns the total linear size of this extent<N> in units of elements. Example code extent<2> e(3, 4); _ASSERT(e.rank == 2); _ASSERT(e.size() == 3 * 4); e += 3; e[1] += 6; e = e + index<2>(3,-4); _ASSERT(e == extent<2>(9, 9)); _ASSERT( e.contains(index<2>(8, 8))); _ASSERT(!e.contains(index<2>(8, 9))); grid<N> Our upcoming pre-release bits also have a similar type to extent, grid<N>. The way you create a grid is by passing it an extent, e.g. extent<3> e(4,2,6); grid<3> g(e); I am not going to dive deeper into grid, suffice for now to think of grid<N> simply as an alias for the extent<N> object, that you create when you encounter a function that expects a grid object instead of an extent object. Usage The extent class on its own simply defines the size of the N-dimensional space. We'll see in future posts that when you create containers (arrays) and wrappers (array_views) for your data, it is an extent<N> object that you'll need to use to create those (and use an index<N> object to index into them). We'll also see that it is a grid<N> object that you pass to the new parallel_for_each function that I'll cover in the next post. Comments about this post by Daniel Moth welcome at the original blog.

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  • PASS: Board Q&amp;A at the Summit

    - by Bill Graziano
    The last two years we’ve put the Board in front of the members and taken questions.  We’re going to do that again this year.  It will be in Room 307/308 from 12:15 to 1:30 on Friday. Yes, this time overlaps with the Birds of a Feather Lunch and the start of afternoon sessions – but only partially.  You can attend the Q&A and still get to parts of both of those.  There just isn’t a great time to do this.  Every time overlaps with something. We can’t do it after the last session on Friday.  We can’t fit it between the last session and the evening events on Wednesday or Thursday.  We had some discussion around breakfast time but I didn’t think that was realistic.  This is the least bad time we could come up with. Last year we had 60-70 people attend.  These are the items that were specific things that I could work on: The first question was whether to increase transparency around individual votes of Board members.  We approved this at the Board meeting the following day.  The only caveat was that if the Board is given confidential information as a basis for their vote then we may not be able to disclose individual votes.  Putting a Director in a position where they can’t publicly defend the reason for their vote is a difficult situation.  Thanks Kendal! Can we have a Board member discretionary fund?  As background, I took a couple of people to lunch so we could have a quiet place to talk.  I bought lunch but wasn’t able to expense it back to PASS.  We just don’t have a budget item for things like this.  I think we should.  I would guess the entire Board would like it also.  It was in an earlier version of the budget but came out as part of a cost-cutting move to balance the budget.  I’d like to see it added back in but we’ll have to see. I know there were a comments about the elections.  At this point we had created the Election Review Committee.  I’ve already written at length about this process. Where does IT work go?  PASS started to publish our internal management reports starting in December 2010.  You can find them on our Governance page.  These aren’t filtered at all and include a variety of information about IT projects.  The most recent update had roughly a page of updates related to IT.  Lots of the work was related to Summit and the Orator tool that we use to manage speaker submissions. There were numerous requests that Tina Turner not be repeated.  Done.  I don’t think we’ll do anything quite like that again.  We had a request for a payment plan for Summit.  We looked into this briefly but didn’t take any action.  We didn’t think the effort was worth the small number of people that would use it.  If you disagree, submit this on our Summit Feedback site and get some votes. There were lots of suggestions around the first-timers events – especially from first timers.  You can find all our current activities related to first-timers at the First Timers page on the Summit web site.  Plus links to 34 (!) blog posts on suggestions for first-timers.  And a big THANK YOU to Confio and Red Gate for sponsoring this. I hope you get the chance to attend.  These events are very helpful to me as a Board member.  I like being able to look around the room as comments are being made and see the audience reaction.  It helps me gauge the interest in an idea. I’d also like to direct you to the Summit Feedback site.  You can submit and vote on ideas to make the Summit a better experience.  As of right now we have the suggestions from last year still up.  We may reset these prior to the Summit though.

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  • concurrency::index<N> from amp.h

    - by Daniel Moth
    Overview C++ AMP introduces a new template class index<N>, where N can be any value greater than zero, that represents a unique point in N-dimensional space, e.g. if N=2 then an index<2> object represents a point in 2-dimensional space. This class is essentially a coordinate vector of N integers representing a position in space relative to the origin of that space. It is ordered from most-significant to least-significant (so, if the 2-dimensional space is rows and columns, the first component represents the rows). The underlying type is a signed 32-bit integer, and component values can be negative. The rank field returns N. Creating an index The default parameterless constructor returns an index with each dimension set to zero, e.g. index<3> idx; //represents point (0,0,0) An index can also be created from another index through the copy constructor or assignment, e.g. index<3> idx2(idx); //or index<3> idx2 = idx; To create an index representing something other than 0, you call its constructor as per the following 4-dimensional example: int temp[4] = {2,4,-2,0}; index<4> idx(temp); Note that there are convenience constructors (that don’t require an array argument) for creating index objects of rank 1, 2, and 3, since those are the most common dimensions used, e.g. index<1> idx(3); index<2> idx(3, 6); index<3> idx(3, 6, 12); Accessing the component values You can access each component using the familiar subscript operator, e.g. One-dimensional example: index<1> idx(4); int i = idx[0]; // i=4 Two-dimensional example: index<2> idx(4,5); int i = idx[0]; // i=4 int j = idx[1]; // j=5 Three-dimensional example: index<3> idx(4,5,6); int i = idx[0]; // i=4 int j = idx[1]; // j=5 int k = idx[2]; // k=6 Basic operations Once you have your multi-dimensional point represented in the index, you can now treat it as a single entity, including performing common operations between it and an integer (through operator overloading): -- (pre- and post- decrement), ++ (pre- and post- increment), %=, *=, /=, +=, -=,%, *, /, +, -. There are also operator overloads for operations between index objects, i.e. ==, !=, +=, -=, +, –. Here is an example (where no assertions are broken): index<2> idx_a; index<2> idx_b(0, 0); index<2> idx_c(6, 9); _ASSERT(idx_a.rank == 2); _ASSERT(idx_a == idx_b); _ASSERT(idx_a != idx_c); idx_a += 5; idx_a[1] += 3; idx_a++; _ASSERT(idx_a != idx_b); _ASSERT(idx_a == idx_c); idx_b = idx_b + 10; idx_b -= index<2>(4, 1); _ASSERT(idx_a == idx_b); Usage You'll most commonly use index<N> objects to index into data types that we'll cover in future posts (namely array and array_view). Also when we look at the new parallel_for_each function we'll see that an index<N> object is the single parameter to the lambda, representing the (multi-dimensional) thread index… In the next post we'll go beyond being able to represent an N-dimensional point in space, and we'll see how to define the N-dimensional space itself through the extent<N> class. Comments about this post by Daniel Moth welcome at the original blog.

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  • How to efficiently map tokens to code in a script interpreter?

    - by lithander
    I'm writing an interpreter for a simple scripting language where each line is a complete, executable command. (Like the instructions in assembler) When parsing a line I have to map the requested command to actual code. My current solution looks like this: std::string op, param1, param2; //parse line, identify op, param1, param2 ... //call command specific code if(op == "MOV") ExecuteMov(AsNumber(param1)); else if(op == "ROT") ExecuteRot(AsNumber(param1)); else if(op == "SZE") ExecuteSze(AsNumber(param1)); else if(op == "POS") ExecutePos((AsNumber(param1), AsNumber(param2)); else if(op == "DIR") ExecuteDir((AsNumber(param1), AsNumber(param2)); else if(op == "SET") ExecuteSet(param1, AsNumber(param2)); else if(op == "EVL") ... The more commands are supported the more string comparisions I'll have to do to identify and call the associated method. Can you point me to a more efficient implementation in the described scenario?

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  • mono --aot with MinGW: unknown pseudo-op: `.local'

    - by Jared Updike
    Can I user mono's AOT feature to natively "pre-compile" .NET DLLs (and or EXEs) to make them harder to reverse engineer? If so, how do I get mono/AOT working in Windows 7? (I'm running x64 but the app is targeting x86 explicitly.) I just installed Mono 2.6.3 and MinGW 5.1.6 and I'm trying to AOT compile an exe (or a dll, it doesn't matter). I get screens and screens of error messages: C:\Users\jupdike\AppData\Local\Temp\mono_aot_XSDEAV:533: Error: junk at end of line, first unrecognized character is `H' C:\Users\jupdike\AppData\Local\Temp\mono_aot_XSDEAV:539: Error: unknown pseudo-op: `.local' C:\Users\jupdike\AppData\Local\Temp\mono_aot_XSDEAV:546: Warning: .size pseudo-op used outside of .def/.endef ignored. C:\Users\jupdike\AppData\Local\Temp\mono_aot_XSDEAV:546: Error: junk at end of line, first unrecognized character is `H' I can open the generated assembly code but I have no idea why the assembler chokes on it: .size HappyForms_TextForm__ctor_string_string_string_bool,.-HappyForms_TextForm__ctor_string_string_string_bool (533) _.Lme_a: .Lme_a: .balign 16 _.Lm_b: .Lm_b: .local HappyForms_TextForm_get_InputValue (539) _HappyForms_TextForm_get_InputValue: HappyForms_TextForm_get_InputValue: .byte 85,139,236,131,236,8,139,69,8,139,128,216,2,0,0,131,236,12,80,139,0,144,144,144,255,144,200,2,0,0,131,196 .byte 16,201,195 .size HappyForms_TextForm_get_InputValue,.-HappyForms_TextForm_get_InputValue (546) (numbers above in parens are line numbers)

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  • Javascript: Can't control parent of descendant nodes.

    - by .phjasper
    I'm creating elements (level 1) dynamically which in turn create elements (level 2) themselves. However, the children of level 2 elements have "body" as their parent. In the HTML code below, the content if spotAd2 is created by my function createNode(). It's a Google Ad Sense tag. However, the Google Ad Sense tag create elements that went directly under "body". I need them to by under spotAd2. function createNode( t, // type. tn, // if type is element, tag name. a, // if type is element, attributes. v, // node value or text content p, // parent f ) // whether to make dist the first child or not. { n = null; switch( t ) { case "element": n = document.createElement( tn ); if( a ) { for( k in a ) { n.setAttribute( k, a[ k ] ); } } break; case "text": case "cdata_section": case "comment": n = document.createTextNode(v); break; } if ( p ) { if( f ) { p.insertBefore( n, p.firstChild ); } else { p.appendChild( n ); } } return n; } spotAd2 = document.getElementById("spotAd2"); n1 = createNode("element", "div", {"id":"tnDiv1"}, "\n" , null, true); n2 = createNode("element", "script", {"type":"text\/javascript"}, "\n" , n1, false); n3 = createNode("comment", "", null, "\n" + "google_ad_client = \"pub-0321943928525350\";\n" + "/* 728x90 (main top) */\n" + "google_ad_slot = \"2783893649\";\n" + "google_ad_width = 728;\n" + "google_ad_height = 90;\n" + "//\n" , n2, false); n4 = createNode("element", "script", {"type":"text\/javascript","src":"http:\/\/pagead2.googlesyndication.com\/pagead\/show_ads.js"}, "\n" , n1, false); --- Result: <body> <table cellspacing="2" cellpadding="2" border="1"> <tbody><tr> <td>Oel ngati kemeie</td> <td>Kamakto niwin</td> </tr> <tr> <td>The ad:</td> <td> <div id="spotAd2"> <!-- Created by createNode() --> <div id="tnDiv1"> <script type="text/javascript"> google_ad_client = "pub-0321943928525350"; /* 728x90 (main top) */ google_ad_slot = "2783893649"; google_ad_width = 728; google_ad_height = 90; </script> <script type="text/javascript" src="http://pagead2.googlesyndication.com/pagead/show_ads.js"></script> </div> <!-- Created by createNode() --> </div> </td> </tr> <tr> <td>txopu ra'a tsi, tsamsiyu</td> <td>teyrakup skxawng</td> </tr> </tbody></table> <!-- Created by adsense tag, need these to be under tnDiv1 --> <script src="http://pagead2.googlesyndication.com/pagead/expansion_embed.js"></script> <script src="http://googleads.g.doubleclick.net/pagead/test_domain.js"></script> <script>google_protectAndRun("ads_core.google_render_ad", google_handleError, google_render_ad);</script> <ins style="border: medium none ; margin: 0pt; padding: 0pt; display: inline-table; height: 90px; position: relative; visibility: visible; width: 728px;"> <ins style="border: medium none ; margin: 0pt; padding: 0pt; display: block; height: 90px; position: relative; visibility: visible; width: 728px;"> <iframe width="728" scrolling="no" height="90" frameborder="0" vspace="0" style="left: 0pt; position: absolute; top: 0pt;" src="http://googleads.g.doubleclick.net/pagead/ads?client=ca-pub-0321943928525350&amp;output=html&amp;h=90&amp;slotname=2783893649&amp;w=728&amp;lmt=1273708979&amp;flash=10.0.45&amp;url=http%3A%2F%2Fkenshin.katanatechworks.com%2Ftest%2FadsBrowserSide.php&amp;dt=1273708980294&amp;shv=r20100422&amp;correlator=1273708980298&amp;frm=0&amp;ga_vid=695691836.1273708981&amp;ga_sid=1273708981&amp;ga_hid=1961182006&amp;ga_fc=0&amp;u_tz=480&amp;u_his=2&amp;u_java=1&amp;u_h=1080&amp;u_w=1920&amp;u_ah=1052&amp;u_aw=1920&amp;u_cd=24&amp;u_nplug=5&amp;u_nmime=38&amp;biw=1394&amp;bih=324&amp;fu=0&amp;ifi=1&amp;dtd=955&amp;xpc=Jl67G4xiq6&amp;p=http%3A//kenshin.katanatechworks.com" name="google_ads_frame" marginwidth="0" marginheight="0" id="google_ads_frame1" hspace="0" allowtransparency="true"> </iframe> </ins> </ins> <!-- Created by adsense tag, need these to be under tnDiv1 --> </body>

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