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  • How to test if an array contains a pair of numbers whose product is odd?

    - by John
    How can I write a function that takes an array of integers and returns true if their exists a pair of numbers whose product is odd? What are the properties of odd integers? And of course, how do you write this function in Java? Also, maybe a short explanation of how you went about formulating an algorithm for the actual implementation. Yes, this is a function out of a textbook. No, this is not homework—I'm just trying to learn, so please no "do your own homework comments."

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  • Freeglut ( OpenGL ) in C

    - by user1832149
    I would like to ask for you a little help in my homework. I'm learning at an university of Debrecen, and I would like to be a programmer, but I'm stuck with this homework. It's a OpenGL project in C. (freeglut) The next task is about: Window to viewport transformation. Draw graphs of functions, as shown below. The individual views (viewport) defines four different rectangles. Functions look like this picture: one window in 4 piece, and one pice of one function. The functions, respectively: f(x)=x2 g(x)=x3 h(x)=sin(x) i(x)=cos(x) Heres a pic what I need to make: How would I approach such a task?

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  • Interviews Gone Bad.....Now What Do I Do?

    - by david.talamelli
    We have all done it at some stage of our working careers - you know those times when you leave an interview and then you think to yourself "why didn't I ask that question" or "I can't believe I said that" or "how could I have forgotten to say that". It happens to everyone but how you handle things moving forwards could be critical in helping you land that dream job. There is nothing better than seeing that dream job with the dream company that you are looking to work for advertised (or in some cases getting called by the Recruiter to let you know about that job). The role may seem perfect and it could be just what you are looking for and it is with the right company as well. You have sent in your resume and have subsequently had one, two or maybe three interviews for the role. After each step of the process you get a little bit more excited about the role as you start to think about your work day in your new role/company. Then it happens, you get it: you get The Phone Call to inform you that you have not been successful in securing the position that you have invested so much time and effort into. It can be disappointing to hear this news but what you do next is important in potentially keeping that door open for future opportunities with that company. How you handle yourself in this situation is important: if any of you remember the Choose Your Own Adventure Books do you: Tell the Recruiter (maybe get aggressive) they are wrong in their assessment and that you are the right candidate for the role Switch off and say ok thanks and hang up without engaging in any further dialogue Thank the company for their time and enquire if there may be any other opportunities in the future to explore If you chose the first option - the company in question may consider whether or not to look at you for other opportunities. How you handle yourself in the recruitment process could be an indication of how you would deal with clients/colleagues in your role and the impression that you leave a potential employer may be what sticks in their mind when they think of you (eg: isn't that the person who couldn't handle it when we told him he wasn't right for our role). The second option potentially produces a similar outcome. If you rush to get off the phone, the company may come back to you to talk about other roles when they come up, but you also leave open the potential thought with the company you were only interested in that role and therefore not interested in any other opportunities. Why take the risk of the company thinking that and potentially not getting back to you in the future. By picking the third option, you actively engage with the company and keep the dialogue open for future discussions. Ok, so you didn't get the role you interviewed for - you don't know who else the company may have been interviewing - maybe they found someone who was a better fit, or maybe there were too many boxes you didn't tick to step straight into that specific role. Take a deep breath and keep the company engaged. You are fresh in their mind - take advantage of that fact and let them know that while you respect their decision, that you are still interested in the company and would like to be kept in mind for future roles. Ask if it is ok to keep in touch and when they would like to keep in touch, as long as you are interested let them know you are still interested. You do need to balance that though if you come across as too keen or start stalking people - it could equally damage your brand. Companies normally have more than one open role. New roles are created all the time, circumstances change and hiring people is not a static business, it changes course from everyone's best laid initial plans. If you didn't get that initial role you wanted, keep the door open with that company so that when those new roles do come up or when circumstances do change you have already laid the ground to step into those new positions.

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  • #iPad at One Week: A Great Device Made with a Heavy Hand

    - by andrewbrust
    I have now had my iPad for a little over a week. In that time, Apple introduced the world to its iPhone OS 4 (and the SDK agreement’s draconian new section 3.3.1), HP introduced is Slate, and Microsoft got ready to launch Visual Studio 2010 and .NET 4.0. And through it all I have used my iPad. I've used it for email, calendar, controlling my Sonos, and writing an essay. I've used it for getting on TripIt and Twitter, and surfing the Web. I've used it for online banking, and online ordering and delivery of food. And the verdict? Honestly? I think it's a great device and I thoroughly enjoy using it. The screen is bright and vibrant. I am surprisingly fast and accurate when I type on it. The touch screen's responsiveness is nearly flawless. The software, including a number of third party applications, include pleasing animations and use of color that make it fun to get work done. And speaking of work, the Exchange integration is, dare I say it, robust. Not as full-featured as on a PC or Windows Mobile device, but still offering core functionality and, so far at least, without bugs. The UI is intuitive, not just to me, but also to my 5 1/2 year old, and also to my nearly-3-year-old son. They picked it up and, with just just a few pointers from me, they almost immediately knew what to do, whether they were looking at photos (and swiping/flicking along as they did so), using a drawing program, playing a game, or watching YouTube videos. The younger of the two of them even tried to get up on a chair and grab the thing today. He dropped it, from about 4 feet off the ground. And it's still fine. (Meanwhile, I'll be keeping it on a higher shelf.) I cannot fully describe yet what makes this form factor and this product so appealing. Maybe it's that it's an always-on device. Maybe it's just being able to hold such a nice, relatively large display so close. Maybe it's the design sensibility, that seems to pervade throughout the app ecosystem. Or maybe it's that one's fingers, and not pens or mice, are the software's preferred input device. Whatever the attraction, it's strong. And no matter how much I tend to root for Microsoft and against Apple, Cupertino has, in my mind, scored big, Can Microsoft compete? Yes, but not with the Windows 7 standard UI (nor with individual OEMs’ own UIs on top). I hope Microsoft builds a variant of the Windows Phone 7 specifically for tablet devices. And I hope they make it clear that all developers, and programming languages, are welcome to the platform. Once that’s established, the OEMs have to build great hardware with fast, responsive touch screens, under Microsoft's watchful eye. That may be the hardest part of getting this right. No matter what, Microsoft's got a fight on its hands. I don't know if it can count on winning that fight, either. But Silverlight and Live Tiles could certainly help. And so can treating developers like adults.  Apple seems intent on treating their devs like kids, and then giving the kids a curfew.  For that, dev-friendly Microsoft may one day give thanks.

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  • Day 5 - Tada! My Game Menu Screen Graphics

    - by dapostolov
    So, tonight I took some time to mash up some graphics for my game menu screen. My artistic talent sucks...but here goes nothing...voila, my menu screen!! The Menu Screen The screen above is displaying 4 sprites, even though it looks like maybe 7... I guess one of the first things for me to test in the future is ... is it more memory efficient (and better frame rate) to draw one big background image OR tp paint the screen black, and place each sprite in set locations? To display the 4 sprites above, I borrowed my code from yesterday ... I know, tacky, but...I wanted to see it, feel it. Do you feel it? FEEL IT! (homer voice & shakes fist) Note: the menu items won't scale properly as it stands with this code, well pretty much they do nothing except look pretty... Paint.Net & Google Fun So how did I create that image above? Well, to create the background and 3 menu items I used Paint.Net. Basically, I scoured Google images for: a stone doorway, a stone pillar, an old book, a wizards hat, and...that's it pretty much it! I'll let you type in those searches and see if you can locate the images I used. I know, bad developer...but I figured since I modified the images considerably it doesn't count...well for a personal project it shouldn't count...*shrug* Anyhow, I extracted each key assest I wanted from each image and applied lots of matting, blurring, color changes, glow effects and such. Then, using my vivid imagination I placed / composed each of the layered assets into the mashed up the "scene" above. Pretty cool, eh? Hey, did you know, the cool mist effect is actually a fire rendition in Paint.net? I set it to black & white with opacity set next to nothing. I'm also very proud of the yellow "light" in the stone doorway. I drew that in and then applied gausian blur to it to give it the effect of light creeping out around the door and into the room...heheh. So did I achieve the dark, mysterious ritual as I stated in my design doc? I think I had a great stab at it! Maybe down the road I can get a real artist to crank out some quality graphics for the game... =) So, What's Next? Well, I don't have that animated brazier yet...however, I thought it would be even cooler if I can get that door pulsing that yellow light and it would be extremely cool to have the smoke / mist moving across the screen! Make the creative ideas stop!! (clutches head) haha! I'm having great fun working on this project =) I recommend others giving something like this a try, it's really fulfilling. OK. Tomorrow... I think I'm going to start creating some game / menu objects as per the design doc, maybe even get a custom mouse cursor up on the screen and handle a couple of mouse events, and lastly, maybe a feature to toggle a framerate display... D.

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  • Update iPhone UIProgressView during NSURLConnection download.

    - by Scott Pendleton
    I am using this code: NSURLConnection *oConnection=[[NSURLConnection alloc] initWithRequest:oRequest delegate:self]; to download a file, and I want to update a progress bar on a subview that I load. For that, I use this code: - (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data { [oReceivedData appendData:data]; float n = oReceivedData.length; float d = self.iTotalSize; NSNumber *oNum = [NSNumber numberWithFloat:n/d]; self.oDPVC.oProgress.progress = [oNum floatValue]; } The subview is oDPVC, and the progress bar on it is oProgress. Setting the progress property does not update the control. From what I have read on the Web, lots of people want to do this and yet there is not a complete, reliable sample. Also, there is much contradictory advice. Some people think that you don't need a separate thread. Some say you need a background thread for the progress update. Some say no, do other things in the background and update the progress on the main thread. I've tried all the advice, and none of it works for me. One more thing, maybe this is a clue. I use this code to load the subview during applicationDidFinishLaunching: self.oDPVC = [[DownloadProgressViewController alloc] initWithNibName:@"DownloadProgressViewController" bundle:nil]; [window addSubview:self.oDPVC.view]; In the XIB file (which I have examined in both Interface Builder and in a text editor) the progress bar is 280 pixels wide. But when the view opens, it has somehow been adjusted to maybe half that width. Also, the background image of the view is default.png. Instead of appearing right on top of the default image, it is shoved up about 10 pixels, leaving a white bar across the bottom of the screen. Maybe that's a separate issue, maybe not.

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  • Applications on the Web/Cloud the way to go? over Desktop apps?

    - by jiewmeng
    i am currently a mainly web developer, but is quite attracted to the performance and great integration with the OS (eg. Windows 7, Jump Lists, Taskbar Thumbnails, etc) something like WPF/C# can provide to the user, improving workflow and productivity. privacy and performance seems like a major downside of web/cloud apps compared to desktop apps. applications on the cloud/web work on the go, increased popularity of smartphones/netbooks majority of users may not benefit as much from increased performance of desktop apps, eg. internet surfing, word processing, probably benefit more from decreased startup times, lower costs and data on the cloud desktop applications increased performance benefits power users like 3D rendering, HD video/photo editing, gamers (i wonder if such processing maybe offset to cloud processing) integration with OS increases productivity (maybe such features can be adapted to a web version? maybe with a local desktop app to work with Web App API) more control over privacy (maybe fixed by encryption?) local data access (esp. large files) guaranteed and fast (YouTube HD fast enough most of the time) work not affected by intermittent/slow/availability internet connections (i know this is changing tho) what do you think?

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  • Where can I find a quick reference for standard Basic?

    - by Steve314
    The reason? Pure nostalgia. Anyway, there was a standard for Basic that was published in the late 80s or early 90s. It was probably ISO/IEC 10279:1991, but I don't have access to that and cannot be sure. Whatever this standard was, some of the syntax made its way into Borlands Turbo Basic and Microsofts Visual Basic. I never learned any significant amount of VB, but Turbo Basic is one of those things I played with in my mis-spent youth. At one time, my main reference was an article published in one of the main programming periodicals - maybe Personal Computer World, maybe Byte. A scan of that article (if anyone can even identify it) would be great, but all I really want is a few pages quick reference of that standard syntax. Must be free (I'm not that nostalgic), but it must describe the standard syntax - the whole point is to sort out what is standard as opposed to VB or whatever. EDIT The more I think about this, the more convinced I am that this standard was available around 1987 or 1988. Maybe it was the earlier non-full version of the standard above, or maybe it was pre-acceptance of the standard.

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  • Is there a way to make changes to toggles in my .emacs file apply without re-starting Emacs?

    - by Vivi
    I want to be able to make the changes to my .emacs file without having to reload Emacs. I found three questions which sort of answer what I am asking (you can find them here, here and here), but the problem is that the change I have just made is to a toggle, and as the comments to two of the answers (a1, a2) to those questions explain, the solutions given there (such as M-x reload-file or M-x eval-buffer) don't apply to toggles. I imagine there is a way of toggling the variable again with a command, but if there is a way to reload the whole .emacs and have the all the toggles re-evaluated without having to specify them, I would prefer. In any case, I would also appreciate if someone told me how to toggle the value of a variable so that if I just changed one toggle I can do it with a command rather than re-start Emacs just for that (I am new to Emacs). I don't know how useful this information is, but the change I applied was the following (which I got from this answer to another question): (setq skeleton-pair t) (setq skeleton-pair-on-word t) (global-set-key (kbd "[") 'skeleton-pair-insert-maybe) (global-set-key (kbd "(") 'skeleton-pair-insert-maybe) (global-set-key (kbd "{") 'skeleton-pair-insert-maybe) (global-set-key (kbd "<") 'skeleton-pair-insert-maybe) Edit: I included the above in .emacs and reloaded Emacs, so that the changes took effect. Then I commented all of it out and tried M-x load-file. This doesn't work. The suggestion below (C-x C-e by PP works if I am using it to evaluate the toggle first time, but not when I want to undo it). I would like something that would evaluate the commenting out, if such thing exists... Thanks :)

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  • Safe and polymorphic toEnum

    - by jetxee
    I'd like to write a safe version of toEnum: safeToEnum :: (Enum t, Bounded t) => Int -> Maybe t A naive implementation: safeToEnum :: (Enum t, Bounded t) => Int -> Maybe t safeToEnum i = if (i >= fromEnum (minBound :: t)) && (i <= fromEnum (maxBound :: t)) then Just . toEnum $ i else Nothing main = do print $ (safeToEnum 1 :: Maybe Bool) print $ (safeToEnum 2 :: Maybe Bool) And it doesn't work: safeToEnum.hs:3:21: Could not deduce (Bounded t1) from the context () arising from a use of `minBound' at safeToEnum.hs:3:21-28 Possible fix: add (Bounded t1) to the context of an expression type signature In the first argument of `fromEnum', namely `(minBound :: t)' In the second argument of `(>=)', namely `fromEnum (minBound :: t)' In the first argument of `(&&)', namely `(i >= fromEnum (minBound :: t))' safeToEnum.hs:3:56: Could not deduce (Bounded t1) from the context () arising from a use of `maxBound' at safeToEnum.hs:3:56-63 Possible fix: add (Bounded t1) to the context of an expression type signature In the first argument of `fromEnum', namely `(maxBound :: t)' In the second argument of `(<=)', namely `fromEnum (maxBound :: t)' In the second argument of `(&&)', namely `(i <= fromEnum (maxBound :: t))' As well as I understand the message, the compiler does not recognize that minBound and maxBound should produce exactly the same type as in the result type of safeToEnum inspite of the explicit type declaration (:: t). Any idea how to fix it?

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  • help me to choose between two software architecture

    - by alex
    // stupid title, but I could not think anything smarter I have a code (see below, sorry for long code but it's very-very simple): namespace Option1 { class AuxClass1 { string _field1; public string Field1 { get { return _field1; } set { _field1 = value; } } // another fields. maybe many fields maybe several properties public void Method1() { // some action } public void Method2() { // some action 2 } } class MainClass { AuxClass1 _auxClass; public AuxClass1 AuxClass { get { return _auxClass; } set { _auxClass = value; } } public MainClass() { _auxClass = new AuxClass1(); } } } namespace Option2 { class AuxClass1 { string _field1; public string Field1 { get { return _field1; } set { _field1 = value; } } // another fields. maybe many fields maybe several properties public void Method1() { // some action } public void Method2() { // some action 2 } } class MainClass { AuxClass1 _auxClass; public string Field1 { get { return _auxClass.Field1; } set { _auxClass.Field1 = value; } } public void Method1() { _auxClass.Method1(); } public void Method2() { _auxClass.Method2(); } public MainClass() { _auxClass = new AuxClass1(); } } } class Program { static void Main(string[] args) { // Option1 Option1.MainClass mainClass1 = new Option1.MainClass(); mainClass1.AuxClass.Field1 = "string1"; mainClass1.AuxClass.Method1(); mainClass1.AuxClass.Method2(); // Option2 Option2.MainClass mainClass2 = new Option2.MainClass(); mainClass2.Field1 = "string2"; mainClass2.Method1(); mainClass2.Method2(); Console.ReadKey(); } } What option (option1 or option2) do you prefer ? In which cases should I use option1 or option2 ? Is there any special name for option1 or option2 (composition, aggregation) ?

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  • How to use python to create a GUI application which have cool animation/effects under Linux (like 3D

    - by sgon00
    Hi, I am not sure if my question title makes sense to you or not. I am seeing many cool applications which have cool animations/effects. I would like to learn how to use python to create this kind of GUI applications under Linux. "cool animation/effects" like 3D wall in Cooliris which is written in flash and compiz effects with opengl. I also heard of some python GUI library like wxPython and pyQT. Since I am completely new to python GUI programming, can anyone suggest me where to start and what I should learn to achieve and create such application? maybe learn pyQT with openGL feature? pyopengl binding? I have no clue on where to start. thank you very much for your time and suggestion. By the way, in case if someone need to know which kind of application I am going to create, well, just any kind of applications. maybe photo explorer with 3D wall, maybe IM client, maybe facebook client etc...

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  • Internal Java code best practice for dealing with invalid REST API parameters

    - by user326389
    My colleague wrote the following stackoverflow question: other stack overflow question on this topic The question seems to have been misinterpreted and I want to find out the answer, so I'm starting this new question... hopefully a little more clear. Basically, we have a REST API. Users of our API call our methods with parameters. But sometimes users call them with the wrong parameters!! Maybe a mistake in their code, maybe they're just trying to play with us, maybe they're trying to see how we respond, who knows! We respond with HTTP status error codes and maybe a detailed description of the invalid parameter in the XML response. All is well. But internally we deal with these invalid parameters by throwing exceptions. For example, if someone looks up a Person object by giving us their profile id, but the profile id doesn't exist... we throw a PersonInvalidException when looking them up. Then we catch this exception in our API controller and send back an HTTP 400 status error code. Our question is... is this the best practice, throwing exceptions internally for this kind of user error? These exceptions never get propogated back to the user, this is a REST API. They only make our code cleaner. Otherwise we could have a validation method in each of our API controllers to make sure the parameters all make sense, but that seems inefficient. We have to look up things in our database potentially twice. Or we could return nulls and check for them, but that sucks... What are your thoughts?

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  • help me to choose between two designs

    - by alex
    // stupid title, but I could not think anything smarter I have a code (see below, sorry for long code but it's very-very simple): namespace Option1 { class AuxClass1 { string _field1; public string Field1 { get { return _field1; } set { _field1 = value; } } // another fields. maybe many fields maybe several properties public void Method1() { // some action } public void Method2() { // some action 2 } } class MainClass { AuxClass1 _auxClass; public AuxClass1 AuxClass { get { return _auxClass; } set { _auxClass = value; } } public MainClass() { _auxClass = new AuxClass1(); } } } namespace Option2 { class AuxClass1 { string _field1; public string Field1 { get { return _field1; } set { _field1 = value; } } // another fields. maybe many fields maybe several properties public void Method1() { // some action } public void Method2() { // some action 2 } } class MainClass { AuxClass1 _auxClass; public string Field1 { get { return _auxClass.Field1; } set { _auxClass.Field1 = value; } } public void Method1() { _auxClass.Method1(); } public void Method2() { _auxClass.Method2(); } public MainClass() { _auxClass = new AuxClass1(); } } } class Program { static void Main(string[] args) { // Option1 Option1.MainClass mainClass1 = new Option1.MainClass(); mainClass1.AuxClass.Field1 = "string1"; mainClass1.AuxClass.Method1(); mainClass1.AuxClass.Method2(); // Option2 Option2.MainClass mainClass2 = new Option2.MainClass(); mainClass2.Field1 = "string2"; mainClass2.Method1(); mainClass2.Method2(); Console.ReadKey(); } } What option (option1 or option2) do you prefer ? In which cases should I use option1 or option2 ? Is there any special name for option1 or option2 (composition, aggregation) ?

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  • Internet Protocol Suite: Transition Control Protocol (TCP) vs. User Datagram Protocol (UDP)

    How do we communicate over the Internet?  How is data transferred from one machine to another? These types of act ivies can only be done by using one of two Internet protocols currently. The collection of Internet Protocol consists of the Transition Control Protocol (TCP) and the User Datagram Protocol (UDP).  Both protocols are used to send data between two network end points, however they both have very distinct ways of transporting data from one endpoint to another. If transmission speed and reliability is the primary concern when trying to transfer data between two network endpoints then TCP is the proper choice. When a device attempts to send data to another endpoint using TCP it creates a direct connection between both devices until the transmission has completed. The direct connection between both devices ensures the reliability of the transmission due to the fact that no intermediate devices are needed to transfer the data. Due to the fact that both devices have to continuously poll the connection until transmission has completed increases the resources needed to perform the transmission. An example of this type of direct communication can be seen when a teacher tells a students to do their homework. The teacher is talking directly to the students in order to communicate that the homework needs to be done.  Students can then ask questions about the assignment to ensure that they have received the proper instructions for the assignment. UDP is a less resource intensive approach to sending data between to network endpoints. When a device uses UDP to send data across a network, the data is broken up and repackaged with the destination address. The sending device then releases the data packages to the network, but cannot ensure when or if the receiving device will actually get the data.  The sending device depends on other devices on the network to forward the data packages to the destination devices in order to complete the transmission. As you can tell this type of transmission is less resource intensive because not connection polling is needed,  but should not be used for transmitting data with speed or reliability requirements. This is due to the fact that the sending device can not ensure that the transmission is received.  An example of this type of communication can be seen when a teacher tells a student that they would like to speak with their parents. The teacher is relying on the student to complete the transmission to the parents, and the teacher has no guarantee that the student will actually inform the parents about the request. Both TCP and UPD are invaluable when attempting to send data across a network, but depending on the situation one protocol may be better than the other. Before deciding on which protocol to use an evaluation for transmission speed, reliability, latency, and overhead must be completed in order to define the best protocol for the situation.  

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  • Surface of Revolution with 3D surface

    - by user5584
    I have to use this function to get a Surface of Revolution (homework). newVertex = (oldVertex.y, someFunc1(oldVertex.x, oldVertex.y), someFunc2(oldVertex.x, oldVertex.y)); As far as I know (FIXME) Surface of Revolution means rotations of a (2D)curve around an axis in 3D. But this vertex computing gives a 3D plane (FIXME again :D), so rotation of this isn't obvious. Am I misunderstanding something?

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  • Routes on a sphere surface - Find geodesic?

    - by CaNNaDaRk
    I'm working with some friends on a browser based game where people can move on a 2D map. It's been almost 7 years and still people play this game so we are thinking of a way to give them something new. Since then the game map was a limited plane and people could move from (0, 0) to (MAX_X, MAX_Y) in quantized X and Y increments (just imagine it as a big chessboard). We believe it's time to give it another dimension so, just a couple of weeks ago, we began to wonder how the game could look with other mappings: Unlimited plane with continous movement: this could be a step forward but still i'm not convinced. Toroidal World (continous or quantized movement): sincerely I worked with torus before but this time I want something more... Spherical world with continous movement: this would be great! What we want Users browsers are given a list of coordinates like (latitude, longitude) for each object on the spherical surface map; browsers must then show this in user's screen rendering them inside a web element (canvas maybe? this is not a problem). When people click on the plane we convert the (mouseX, mouseY) to (lat, lng) and send it to the server which has to compute a route between current user's position to the clicked point. What we have We began writing a Java library with many useful maths to work with Rotation Matrices, Quaternions, Euler Angles, Translations, etc. We put it all together and created a program that generates sphere points, renders them and show them to the user inside a JPanel. We managed to catch clicks and translate them to spherical coords and to provide some other useful features like view rotation, scale, translation etc. What we have now is like a little (very little indeed) engine that simulates client and server interaction. Client side shows points on the screen and catches other interactions, server side renders the view and does other calculus like interpolating the route between current position and clicked point. Where is the problem? Obviously we want to have the shortest path to interpolate between the two route points. We use quaternions to interpolate between two points on the surface of the sphere and this seemed to work fine until i noticed that we weren't getting the shortest path on the sphere surface: We though the problem was that the route is calculated as the sum of two rotations about X and Y axis. So we changed the way we calculate the destination quaternion: We get the third angle (the first is latitude, the second is longitude, the third is the rotation about the vector which points toward our current position) which we called orientation. Now that we have the "orientation" angle we rotate Z axis and then use the result vector as the rotation axis for the destination quaternion (you can see the rotation axis in grey): What we got is the correct route (you can see it lays on a great circle), but we get to this ONLY if the starting route point is at latitude, longitude (0, 0) which means the starting vector is (sphereRadius, 0, 0). With the previous version (image 1) we don't get a good result even when startin point is 0, 0, so i think we're moving towards a solution, but the procedure we follow to get this route is a little "strange" maybe? In the following image you get a view of the problem we get when starting point is not (0, 0), as you can see starting point is not the (sphereRadius, 0, 0) vector, and as you can see the destination point (which is correctly drawn!) is not on the route. The magenta point (the one which lays on the route) is the route's ending point rotated about the center of the sphere of (-startLatitude, 0, -startLongitude). This means that if i calculate a rotation matrix and apply it to every point on the route maybe i'll get the real route, but I start to think that there's a better way to do this. Maybe I should try to get the plane through the center of the sphere and the route points, intersect it with the sphere and get the geodesic? But how? Sorry for being way too verbose and maybe for incorrect English but this thing is blowing my mind! EDIT: This code version is related to the first image: public void setRouteStart(double lat, double lng) { EulerAngles tmp = new EulerAngles ( Math.toRadians(lat), 0, -Math.toRadians(lng)); //set route start Quaternion qtStart.setInertialToObject(tmp); //do other stuff like drawing start point... } public void impostaDestinazione(double lat, double lng) { EulerAngles tmp = new AngoliEulero( Math.toRadians(lat), 0, -Math.toRadians(lng)); qtEnd.setInertialToObject(tmp); //do other stuff like drawing dest point... } public V3D interpolate(double totalTime, double t) { double _t = t/totalTime; Quaternion q = Quaternion.Slerp(qtStart, qtEnd, _t); RotationMatrix.inertialQuatToIObject(q); V3D p = matInt.inertialToObject(V3D.Xaxis.scale(sphereRadius)); //other stuff, like drawing point ... return p; } //mostly taken from a book! public static Quaternion Slerp(Quaternion q0, Quaternion q1, double t) { double cosO = q0.dot(q1); double q1w = q1.w; double q1x = q1.x; double q1y = q1.y; double q1z = q1.z; if (cosO < 0.0f) { q1w = -q1w; q1x = -q1x; q1y = -q1y; q1z = -q1z; cosO = -cosO; } double sinO = Math.sqrt(1.0f - cosO*cosO); double O = Math.atan2(sinO, cosO); double oneOverSinO = 1.0f / senoOmega; k0 = Math.sin((1.0f - t) * O) * oneOverSinO; k1 = Math.sin(t * O) * oneOverSinO; // Interpolate return new Quaternion( k0*q0.w + k1*q1w, k0*q0.x + k1*q1x, k0*q0.y + k1*q1y, k0*q0.z + k1*q1z ); } A little dump of what i get (again check image 1): Route info: Sphere radius and center: 200,000, (0.0, 0.0, 0.0) Route start: lat 0,000 °, lng 0,000 ° @v: (200,000, 0,000, 0,000), |v| = 200,000 Route end: lat 30,000 °, lng 30,000 ° @v: (150,000, 86,603, 100,000), |v| = 200,000 Qt dump: (w, x, y, z), rot. angle°, (x, y, z) rot. axis Qt start: (1,000, 0,000, -0,000, 0,000); 0,000 °; (1,000, 0,000, 0,000) Qt end: (0,933, 0,067, -0,250, 0,250); 42,181 °; (0,186, -0,695, 0,695) Route start: lat 30,000 °, lng 10,000 ° @v: (170,574, 30,077, 100,000), |v| = 200,000 Route end: lat 80,000 °, lng -50,000 ° @v: (22,324, -26,604, 196,962), |v| = 200,000 Qt dump: (w, x, y, z), rot. angle°, (x, y, z) rot. axis Qt start: (0,962, 0,023, -0,258, 0,084); 31,586 °; (0,083, -0,947, 0,309) Qt end: (0,694, -0,272, -0,583, -0,324); 92,062 °; (-0,377, -0,809, -0,450)

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  • Geek City: Growing Rows with Snapshot Isolation

    - by Kalen Delaney
    I just finished a wonderful week in Stockholm, teaching a class for Cornerstone Education. We had 19 SQL Server enthusiasts, all eager to find out everything they could about SQL Server Internals. One questions came up on Thursday that I wasn’t sure of the answer to. I jokingly told the student who asked it to consider it a homework exercise, but then I was so interested in the answer, I try to figure it out myself Thursday evening. In this post, I’ll tell you what I did to try to answer the question....(read more)

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  • XenApp 6.5 – How to create and set a Policy using PowerShell

    - by Waclaw Chrabaszcz
    Originally posted on: http://geekswithblogs.net/Wchrabaszcz/archive/2013/06/20/xenapp-6.5--how-to-create-and-set-a-policy.aspxHere is my homework Add-PSSnapin -name Citrix.Common.* -ErrorAction SilentlyContinueNew-Item LocalFarmGpo:\User\MyPolicycd LocalFarmGpo:\User\MyPolicy\Settings\ICA\SecuritySet-ItemProperty .\MinimumEncryptionLevel State EnabledSet-ItemProperty .\MinimumEncryptionLevel Value Bits128cd LocalFarmGpo:\User\MyPolicy\Filters\WorkerGroupNew-Item -Name "All Servers" -Value "All Servers"Set-ItemProperty LocalFarmGpo:\User\MyPolicy -Name Priority -Value 2  So cute …

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  • Do You Care How Fast Your Business Website is? Google Does

    Google - the biggest player in the internet search engine business by far - have many ways that they determine how a certain website ranks within their listing and those criteria keep changing all the time. If you have done a little SEO homework you know that content - fresh, original content - is king but Google have thrown another factor into the mix that you may not think too much about.

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  • Anyone have any opinions about Chilkatsoft? [closed]

    - by Joe Enos
    I'm considering purchasing the Chilkatsoft bundle, which includes a bunch of libraries on lots of technologies. Specifically, I care about .NET compression, encryption, FTP, and mail libraries, but I'm interested in looking at the rest of their stuff as well. Does anyone have any experience using these libraries, or opinions on the company or product in general? The price is right, and the content seems good, so I just want to make sure I do my homework before purchasing. Thanks

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  • SEO Optimization Services Can Help Improve Your Website

    SEO optimization services can potentially help to improve your website as well as save you time and money. When choosing an SEO company make sure the company has a good reputation as not all SEO companies are reputable and one could end up damaging their website as well as reputation by choosing the wrong SEO Company. Make sure you do your homework and find an SEO who will provide quality services.

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  • The Inkremental Architect&acute;s Napkin - #4 - Make increments tangible

    - by Ralf Westphal
    Originally posted on: http://geekswithblogs.net/theArchitectsNapkin/archive/2014/06/12/the-inkremental-architectacutes-napkin---4---make-increments-tangible.aspxThe driver of software development are increments, small increments, tiny increments. With an increment being a slice of the overall requirement scope thin enough to implement and get feedback from a product owner within 2 days max. Such an increment might concern Functionality or Quality.[1] To make such high frequency delivery of increments possible, the transition from talking to coding needs to be as easy as possible. A user story or some other documentation of what´s supposed to get implemented until tomorrow evening at latest is one side of the medal. The other is where to put the logic in all of the code base. To implement an increment, only logic statements are needed. Functionality like Quality are just about expressions and control flow statements. Think of Assembler code without the CALL/RET instructions. That´s all is needed. Forget about functions, forget about classes. To make a user happy none of that is really needed. It´s just about the right expressions and conditional executions paths plus some memory allocation. Automatic function inlining of compilers which makes it clear how unimportant functions are for delivering value to users at runtime. But why then are there functions? Because they were invented for optimization purposes. We need them for better Evolvability and Production Efficiency. Nothing more, nothing less. No software has become faster, more secure, more scalable, more functional because we gathered logic under the roof of a function or two or a thousand. Functions make logic easier to understand. Functions make us faster in producing logic. Functions make it easier to keep logic consistent. Functions help to conserve memory. That said, functions are important. They are even the pivotal element of software development. We can´t code without them - whether you write a function yourself or not. Because there´s always at least one function in play: the Entry Point of a program. In Ruby the simplest program looks like this:puts "Hello, world!" In C# more is necessary:class Program { public static void Main () { System.Console.Write("Hello, world!"); } } C# makes the Entry Point function explicit, not so Ruby. But still it´s there. So you can think of logic always running in some function. Which brings me back to increments: In order to make the transition from talking to code as easy as possible, it has to be crystal clear into which function you should put the logic. Product owners might be content once there is a sticky note a user story on the Scrum or Kanban board. But developers need an idea of what that sticky note means in term of functions. Because with a function in hand, with a signature to run tests against, they have something to focus on. All´s well once there is a function behind whose signature logic can be piled up. Then testing frameworks can be used to check if the logic is correct. Then practices like TDD can help to drive the implementation. That´s why most code katas define exactly how the API of a solution should look like. It´s a function, maybe two or three, not more. A requirement like “Write a function f which takes this as parameters and produces such and such output by doing x” makes a developer comfortable. Yes, there are all kinds of details to think about, like which algorithm or technology to use, or what kind of state and side effects to consider. Even a single function not only must deliver on Functionality, but also on Quality and Evolvability. Nevertheless, once it´s clear which function to put logic in, you have a tangible starting point. So, yes, what I´m suggesting is to find a single function to put all the logic in that´s necessary to deliver on a the requirements of an increment. Or to put it the other way around: Slice requirements in a way that each increment´s logic can be located under the roof of a single function. Entry points Of course, the logic of a software will always be spread across many, many functions. But there´s always an Entry Point. That´s the most important function for each increment, because that´s the root to put integration or even acceptance tests on. A batch program like the above hello-world application only has a single Entry Point. All logic is reached from there, regardless how deep it´s nested in classes. But a program with a user interface like this has at least two Entry Points: One is the main function called upon startup. The other is the button click event handler for “Show my score”. But maybe there are even more, like another Entry Point being a handler for the event fired when one of the choices gets selected; because then some logic could check if the button should be enabled because all questions got answered. Or another Entry Point for the logic to be executed when the program is close; because then the choices made should be persisted. You see, an Entry Point to me is a function which gets triggered by the user of a software. With batch programs that´s the main function. With GUI programs on the desktop that´s event handlers. With web programs that´s handlers for URL routes. And my basic suggestion to help you with slicing requirements for Spinning is: Slice them in a way so that each increment is related to only one Entry Point function.[2] Entry Points are the “outer functions” of a program. That´s where the environment triggers behavior. That´s where hardware meets software. Entry points always get called because something happened to hardware state, e.g. a key was pressed, a mouse button clicked, the system timer ticked, data arrived over a wire.[3] Viewed from the outside, software is just a collection of Entry Point functions made accessible via buttons to press, menu items to click, gestures, URLs to open, keys to enter. Collections of batch processors I´d thus say, we haven´t moved forward since the early days of software development. We´re still writing batch programs. Forget about “event-driven programming” with its fancy GUI applications. Software is just a collection of batch processors. Earlier it was just one per program, today it´s hundreds we bundle up into applications. Each batch processor is represented by an Entry Point as its root that works on a number of resources from which it reads data to process and to which it writes results. These resources can be the keyboard or main memory or a hard disk or a communication line or a display. Together many batch processors - large and small - form applications the user perceives as a single whole: Software development that way becomes quite simple: just implement one batch processor after another. Well, at least in principle ;-) Features Each batch processor entered through an Entry Point delivers value to the user. It´s an increment. Sometimes its logic is trivial, sometimes it´s very complex. Regardless, each Entry Point represents an increment. An Entry Point implemented thus is a step forward in terms of Agility. At the same time it´s a tangible unit for developers. Therefore, identifying the more or less numerous batch processors in a software system is a rewarding task for product owners and developers alike. That´s where user stories meet code. In this example the user story translates to the Entry Point triggered by clicking the login button on a dialog like this: The batch then retrieves what has been entered via keyboard, loads data from a user store, and finally outputs some kind of response on the screen, e.g. by displaying an error message or showing the next dialog. This is all very simple, but you see, there is not just one thing happening, but several. Get input (email address, password) Load user for email address If user not found report error Check password Hash password Compare hash to hash stored in user Show next dialog Viewed from 10,000 feet it´s all done by the Entry Point function. And of course that´s technically possible. It´s just a bunch of logic and calling a couple of API functions. However, I suggest to take these steps as distinct aspects of the overall requirement described by the user story. Such aspects of requirements I call Features. Features too are increments. Each provides some (small) value of its own to the user. Each can be checked individually by a product owner. Instead of implementing all the logic behind the Login() entry point at once you can move forward increment by increment, e.g. First implement the dialog, let the user enter any credentials, and log him/her in without any checks. Features 1 and 4. Then hard code a single user and check the email address. Features 2 and 2.1. Then check password without hashing it (or use a very simple hash like the length of the password). Features 3. and 3.2 Replace hard coded user with a persistent user directoy, but a very simple one, e.g. a CSV file. Refinement of feature 2. Calculate the real hash for the password. Feature 3.1. Switch to the final user directory technology. Each feature provides an opportunity to deliver results in a short amount of time and get feedback. If you´re in doubt whether you can implement the whole entry point function until tomorrow night, then just go for a couple of features or even just one. That´s also why I think, you should strive for wrapping feature logic into a function of its own. It´s a matter of Evolvability and Production Efficiency. A function per feature makes the code more readable, since the language of requirements analysis and design is carried over into implementation. It makes it easier to apply changes to features because it´s clear where their logic is located. And finally, of course, it lets you re-use features in different context (read: increments). Feature functions make it easier for you to think of features as Spinning increments, to implement them independently, to let the product owner check them for acceptance individually. Increments consist of features, entry point functions consist of feature functions. So you can view software as a hierarchy of requirements from broad to thin which map to a hierarchy of functions - with entry points at the top.   I like this image of software as a self-similar structure on many levels of abstraction where requirements and code match each other. That to me is true agile design: the core tenet of Agility to move forward in increments is carried over into implementation. Increments on paper are retained in code. This way developers can easily relate to product owners. Elusive and fuzzy requirements are not tangible. Software production is moving forward through requirements one increment at a time, and one function at a time. In closing Product owners and developers are different - but they need to work together towards a shared goal: working software. So their notions of software need to be made compatible, they need to be connected. The increments of the product owner - user stories and features - need to be mapped straightforwardly to something which is relevant to developers. To me that´s functions. Yes, functions, not classes nor components nor micro services. We´re talking about behavior, actions, activities, processes. Their natural representation is a function. Something has to be done. Logic has to be executed. That´s the purpose of functions. Later, classes and other containers are needed to stay on top of a growing amount of logic. But to connect developers and product owners functions are the appropriate glue. Functions which represent increments. Can there always be such a small increment be found to deliver until tomorrow evening? I boldly say yes. Yes, it´s always possible. But maybe you´ve to start thinking differently. Maybe the product owner needs to start thinking differently. Completion is not the goal anymore. Neither is checking the delivery of an increment through the user interface of a software. Product owners need to become comfortable using test beds for certain features. If it´s hard to slice requirements thin enough for Spinning the reason is too little knowledge of something. Maybe you don´t yet understand the problem domain well enough? Maybe you don´t yet feel comfortable with some tool or technology? Then it´s time to acknowledge this fact. Be honest about your not knowing. And instead of trying to deliver as a craftsman officially become a researcher. Research an check back with the product owner every day - until your understanding has grown to a level where you are able to define the next Spinning increment. ? Sometimes even thin requirement slices will cover several Entry Points, like “Add validation of email addresses to all relevant dialogs.” Validation then will it put into a dozen functons. Still, though, it´s important to determine which Entry Points exactly get affected. That´s much easier, if strive for keeping the number of Entry Points per increment to 1. ? If you like call Entry Point functions event handlers, because that´s what they are. They all handle events of some kind, whether that´s palpable in your code or note. A public void btnSave_Click(object sender, EventArgs e) {…} might look like an event handler to you, but public static void Main() {…} is one also - for then event “program started”. ?

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