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  • Windows Azure Use Case: High-Performance Computing (HPC)

    - by BuckWoody
    This is one in a series of posts on when and where to use a distributed architecture design in your organization's computing needs. You can find the main post here: http://blogs.msdn.com/b/buckwoody/archive/2011/01/18/windows-azure-and-sql-azure-use-cases.aspx  Description: High-Performance Computing (also called Technical Computing) at its most simplistic is a layout of computer workloads where a “head node” accepts work requests, and parses them out to “worker nodes'”. This is useful in cases such as scientific simulations, drug research, MatLab work and where other large compute loads are required. It’s not the immediate-result type computing many are used to; instead, a “job” or group of work requests is sent to a cluster of computers and the worker nodes work on individual parts of the calculations and return the work to the scheduler or head node for the requestor in a batch-request fashion. This is typical to the way that many mainframe computing use-cases work. You can use commodity-based computers to create an HPC Cluster, such as the Linux application called Beowulf, and Microsoft has a server product for HPC using standard computers, called the Windows Compute Cluster that you can read more about here. The issue with HPC (from any vendor) that some organization have is the amount of compute nodes they need. Having too many results in excess infrastructure, including computers, buildings, storage, heat and so on. Having too few means that the work is slower, and takes longer to return a result to the calling application. Unless there is a consistent level of work requested, predicting the number of nodes is problematic. Implementation: Recently, Microsoft announced an internal partnership between the HPC group (Now called the Technical Computing Group) and Windows Azure. You now have two options for implementing an HPC environment using Windows. You can extend the current infrastructure you have for HPC by adding in Compute Nodes in Windows Azure, using a “Broker Node”.  You can then purchase time for adding machines, and then stop paying for them when the work is completed. This is a common pattern in groups that have a constant need for HPC, but need to “burst” that load count under certain conditions. The second option is to install only a Head Node and a Broker Node onsite, and host all Compute Nodes in Windows Azure. This is often the pattern for organizations that need HPC on a scheduled and periodic basis, such as financial analysis or actuarial table calculations. References: Blog entry on Hybrid HPC with Windows Azure: http://blogs.msdn.com/b/ignitionshowcase/archive/2010/12/13/high-performance-computing-on-premise-and-in-the-windows-azure-cloud.aspx  Links for further research on HPC, includes Windows Azure information: http://blogs.msdn.com/b/ncdevguy/archive/2011/02/16/handy-links-for-hpc-and-azure.aspx 

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  • Oracle Tutor: Are Documented Policies and Procedures Necessary?

    - by emily.chorba(at)oracle.com
    People refer to policies and procedures with a variety of expressions including business process documentation, standard operating procedures (SOPs), department operating procedures (DOPs), work instructions, specifications, and so on. For our purpose here, policies and procedures mean a set of documents that describe an organization's policies (rules) for operation and the procedures (containing tasks performed by individuals) to fulfill the policies. When an organization documents policies and procedures properly, they can be the strategic link between an organization's vision and its daily operations. Policies and procedures are often necessary because of some external requirement, such as environmental compliance or other governmental regulations. One example of an external requirement would be the American Sarbanes-Oxley Act, requiring full openness in accounting practices. Here are a few other examples of business issues that necessitate writing policies and procedures: Operational needs -- policies and procedures ensure fundamental processes are performed in a consistent way that meets the organization's needs. Risk management -- policies and procedures are identified by the Committee of Sponsoring Organizations of the Treadway Commission (COSO) as a control activity needed to manage risk. Continuous improvement -- Procedures can improve processes by building important internal communication practices. Compliance -- Well-defined and documented processes (i.e. procedures, training materials) along with records that demonstrate process capability can demonstrate an effective internal control system compliant with regulations and standards. In addition to helping with the above business issues, policies and procedures can support the basic needs of employees and management. Well documented and easy to access policies and procedures: allow employees to understand their roles and responsibilities within predefined limits and to stay on the accepted path indentified by the organization's management provide clarity to the reader when dealing with accountability issues or activities that are of critical importance allow management to guide operations without constant intervention allow managers to control events in advance and prevent employees from making costly mistakes Can you think of another way organizations can meet the above needs of management and their employees in place of documented Policies and Procedures? Probably not, but we would love your feedback on this question. And that my friends, is why documented policies and procedures are very necessary. Learn MoreFor more information about Tutor, visit Oracle.com or the Tutor Blog. Post your questions at the Tutor Forum. Emily ChorbaPrinciple Product Manager Oracle Tutor & BPM

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  • Computer / Software Engineering vs Other Engineering Disciplines [closed]

    - by Mohammad Yaseen
    Since this was a rather specific question, I have tried my best to present this question in a format which fits the style of this site. Please comment if it can be improved further. I have to choose the Engineering discipline on 6th Nov. My interest is in Robotics, hardware-level programming, Artificial Intelligence and back-end programming. I am currently working as a freelance developer using mainly PHP and occasionally working with GWT.I am somewhat familiar with C# and Python too. I am not super good at programming but I do like it. I am thinking to choose Computer and Information Systems Engineering as this is what I love but all the eggheads of my city are going to Mechanical Engineering and when I ask one of them Why are you choosing this? They say It's my interest and for job and the money. Basically I am confused between CIS and Mechanical Engineering, specifically the job market for both. Since this is a programmers' site I think following questions will be relevant . I am asking this because I want to take advice from professionals in this field before diving too deep . Are you happy with your job / work and pay. Are you satisfied with the work environment and career growth Do you feel OK (or great?) about the near and/or distant future of your industry. Why should a person choose Computer if he has other choices i.e what this industry has to offer in particular which other fields of work don't This industry is subject to rapid changes and you have to learn continuously throughout your entire career. Does this learning and constant hard work pay off ? In my country there is no hardware manufacturing. So most of CIS graduates (like Software Engineers) work in Software Houses. What is the scenario in your country. Is a degree titled 'Software' necessary or companies will take Computer Engineers too if they have relevant experience. I am asking this because I plan to move abroad for work. This is going to be something which I'll do for the rest of my life so I am a bit confused about the right choice. You can view the course outline for both programmes below. Computer and Information Systems Engineering. Mechanical Engineering

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  • How to wire finite state machine into component-based architecture?

    - by Pup
    State machines seem to cause harmful dependencies in component-based architectures. How, specifically, is communication handled between a state machine and the components that carry out state-related behavior? Where I'm at: I'm new to component-based architectures. I'm making a fighting game, although I don't think that should matter. I envision my state machine being used to toggle states like "crouching", "dashing", "blocking", etc. I've found this state-management technique to be the most natural system for a component-based architecture, but it conflicts with techniques I've read about: Dynamic Game Object Component System for Mutable Behavior Characters It suggests that all components activate/deactivate themselves by continually checking a condition for activation. I think that actions like "running" or "walking" make sense as states, which is in disagreement with the accepted response here: finite state machine used in mario like platform game I've found this useful, but ambiguous: How to implement behavior in a component-based game architecture? It suggests having a separate component that contains nothing but a state machine. But, this necessitates some kind of coupling between the state machine component and nearly all the other components. I don't understand how this coupling should be handled. These are some guesses: A. Components depend on state machine: Components receive reference to state machine component's getState(), which returns an enumeration constant. Components update themselves regularly and check this as needed. B. State machine depends on components: The state machine component receives references to all the components it's monitoring. It queries their getState() methods to see where they're at. C. Some abstraction between them Use an event hub? Command pattern? D. Separate state objects that reference components State Pattern is used. Separate state objects are created, which activate/deactivate a set of components. State machine switches between state objects. I'm looking at components as implementations of aspects. They do everything that's needed internally to make that aspect happen. It seems like components should function on their own, without relying on other components. I know some dependencies are necessary, but state machines seem to want to control all of my components.

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  • Handling Coding Standards at Work (I'm not the boss)

    - by Josh Johnson
    I work on a small team, around 10 devs. We have no coding standards at all. There are certain things that have become the norm but some ways of doing things are completely disparate. My big one is indentation. Some use tabs, some use spaces, some use a different number of spaces, which creates a huge problem. I often end up with conflicts when I merge because someone used their IDE to auto format and they use a different character to indent than I do. I don't care which we use I just want us all to use the same one. Or else I'll open a file and some lines have curly brackets on the same line as the condition while others have them on the next line. Again, I don't mind which one so long as they are all the same. I've brought up the issue of standards to my direct manager, one on one and in group meetings, and he is not overly concerned about it (there are several others who share the same view as myself). I brought up my specific concern about indentation characters and he thought a better solution would be to, "create some kind of script that could convert all that when we push/pull from the repo." I suspect that he doesn't want to change and this solution seems overly complicated and prone to maintenance issues down the road (also, this addresses only one manifestation of a larger issue). Have any of you run into a similar situation at work? If so, how did you handle it? What would be some good points to help sell my boss on standards? Would starting a grass roots movement to create coding standards, among those of us who are interested, be a good idea? Am I being too particular, should I just let it go? Thank you all for your time. Note: Thanks everyone for the great feedback so far! To be clear, I don't want to dictate One Style To Rule Them All. I'm willing to concede my preferred way of doing something in favor of what suits everyone the best. I want consistency and I want this to be a democracy. I want it to be a group decision that everyone agrees on. True, not everyone will get their way, but I'm hoping that everyone will be mature enough to compromise for the betterment of the group. Note 2: Some people are getting caught up in the two examples I gave above. I'm more after the heart of the matter. It manifests itself with many examples: naming conventions, huge functions that should be broken up, should something go in a util or service, should something be a constant or injected, should we all use different versions of a dependency or the same, should an interface be used for this case, how should unit tests be set up, what should be unit tested, (Java specific) should we use annotations or external config. I could go on.

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  • Separating physics and game logic from UI code

    - by futlib
    I'm working on a simple block-based puzzle game. The game play consists pretty much of moving blocks around in the game area, so it's a trivial physics simulation. My implementation, however, is in my opinion far from ideal and I'm wondering if you can give me any pointers on how to do it better. I've split the code up into two areas: Game logic and UI, as I did with a lot of puzzle games: The game logic is responsible for the general rules of the game (e.g. the formal rule system in chess) The UI displays the game area and pieces (e.g. chess board and pieces) and is responsible for animations (e.g. animated movement of chess pieces) The game logic represents the game state as a logical grid, where each unit is one cell's width/height on the grid. So for a grid of width 6, you can move a block of width 2 four times until it collides with the boundary. The UI takes this grid, and draws it by converting logical sizes into pixel sizes (that is, multiplies it by a constant). However, since the game has hardly any game logic, my game logic layer [1] doesn't have much to do except collision detection. Here's how it works: Player starts to drag a piece UI asks game logic for the legal movement area of that piece and lets the player drag it within that area Player lets go of a piece UI snaps the piece to the grid (so that it is at a valid logical position) UI tells game logic the new logical position (via mutator methods, which I'd rather avoid) I'm not quite happy with that: I'm writing unit tests for my game logic layer, but not the UI, and it turned out all the tricky code is in the UI: Stopping the piece from colliding with others or the boundary and snapping it to the grid. I don't like the fact that the UI tells the game logic about the new state, I would rather have it call a movePieceLeft() method or something like that, as in my other games, but I didn't get far with that approach, because the game logic knows nothing about the dragging and snapping that's possible in the UI. I think the best thing to do would be to get rid of my game logic layer and implement a physics layer instead. I've got a few questions regarding that: Is such a physics layer common, or is it more typical to have the game logic layer do this? Would the snapping to grid and piece dragging code belong to the UI or the physics layer? Would such a physics layer typically work with pixel sizes or with some kind of logical unit, like my game logic layer? I've seen event-based collision detection in a game's code base once, that is, the player would just drag the piece, the UI would render that obediently and notify the physics system, and the physics system would call a onCollision() method on the piece once a collision is detected. What is more common? This approach or asking for the legal movement area first? [1] layer is probably not the right word for what I mean, but subsystem sounds overblown and class is misguiding, because each layer can consist of several classes.

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  • How to deal with a boss who is extremely competitive [closed]

    - by user72101
    Okay, so I recently joined this group. My boss who I reported to, left a while ago and my colleague was made the team lead. We both now report to the same head, but she heads the team I work in. I am not sure on how to deal with various situations. I would imagine a team lead who motivates the rest of the team, and not someone who would take credit for what others do. I am the only one who works at the same geographic location. She is very smart, no doubt about it. Things get to me, for example I work on an issue and email a dev team, she would respond on top of my emails and as she is the lead, people respond to her rather than to me. If there is an email addressed with the head on it, she would get it to faster than I do, even when she knew I am looking into it. The rest of the team keeps asking me questions or help. I find it hard to say no, and I try to help them as i feel I might need their help someday as well. I slack in my own work or I could have used the time to learn things. I feel that she should be the go to person and not me. If one gets the benefits of being a lead, why not the work that goes with it? I feel I am stuck in a very unfortunate situation and am totally helpless about it. Everyday it is something or the other. I work on a project for months and finally when it is about to go live and there was a minor issue and the head started asking questions, she completely stole my thunder on a call. She would not let me speak and I have to actually cut her off to speak up. The ideal would be not to give it a thought and just do the best I can,but I feel I am capable of much more and not able to give my best because of this constant war at work. Neetu

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  • Dynamic Filtering

    - by Ricardo Peres
    Continuing my previous posts on dynamic LINQ, now it's time for dynamic filtering. For now, I'll focus on string matching. There are three standard operators for string matching, which both NHibernate, Entity Framework and LINQ to SQL recognize: Equals Contains StartsWith EndsWith So, if we want to apply filtering by one of these operators on a string property, we can use this code: public enum MatchType { StartsWith = 0, EndsWith = 1, Contains = 2, Equals = 3 } public static List Filter(IEnumerable enumerable, String propertyName, String filter, MatchType matchType) { return (Filter(enumerable, typeof(T), propertyName, filter, matchType) as List); } public static IList Filter(IEnumerable enumerable, Type elementType, String propertyName, String filter, MatchType matchType) { MethodInfo asQueryableMethod = typeof(Queryable).GetMethods(BindingFlags.Static | BindingFlags.Public).Where(m = (m.Name == "AsQueryable") && (m.ContainsGenericParameters == false)).Single(); IQueryable query = (enumerable is IQueryable) ? (enumerable as IQueryable) : asQueryableMethod.Invoke(null, new Object [] { enumerable }) as IQueryable; MethodInfo whereMethod = typeof(Queryable).GetMethods(BindingFlags.Public | BindingFlags.Static).Where(m = m.Name == "Where").ToArray() [ 0 ].MakeGenericMethod(elementType); MethodInfo matchMethod = typeof(String).GetMethod ( (matchType == MatchType.StartsWith) ? "StartsWith" : (matchType == MatchType.EndsWith) ? "EndsWith" : (matchType == MatchType.Contains) ? "Contains" : "Equals", new Type [] { typeof(String) } ); PropertyInfo displayProperty = elementType.GetProperty(propertyName, BindingFlags.Public | BindingFlags.Instance); MemberExpression member = Expression.MakeMemberAccess(Expression.Parameter(elementType, "n"), displayProperty); MethodCallExpression call = Expression.Call(member, matchMethod, Expression.Constant(filter)); LambdaExpression where = Expression.Lambda(call, member.Expression as ParameterExpression); query = whereMethod.Invoke(null, new Object [] { query, where }) as IQueryable; MethodInfo toListMethod = typeof(Enumerable).GetMethod("ToList", BindingFlags.Static | BindingFlags.Public).MakeGenericMethod(elementType); IList list = toListMethod.Invoke(null, new Object [] { query }) as IList; return (list); } var list = new [] { new { A = "aa" }, new { A = "aabb" }, new { A = "ccaa" }, new { A = "ddaadd" } }; var contains = Filter(list, "A", "aa", MatchType.Contains); var endsWith = Filter(list, "A", "aa", MatchType.EndsWith); var startsWith = Filter(list, "A", "aa", MatchType.StartsWith); var equals = Filter(list, "A", "aa", MatchType.Equals); Perhaps I'll write some more posts on this subject in the near future. SyntaxHighlighter.config.clipboardSwf = 'http://alexgorbatchev.com/pub/sh/2.0.320/scripts/clipboard.swf'; SyntaxHighlighter.brushes.CSharp.aliases = ['c#', 'c-sharp', 'csharp']; SyntaxHighlighter.all();

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  • Overload Avoidance

    - by mikef
    A little under a year ago, Matt Simmons wrote a rather reflective article about his terrifying brush with stress-induced ill health. SysAdmins and DBAs have always been prime victims of work-related stress, but I wonder if that predilection is perhaps getting worse, despite the best efforts of Matt and his trusty side-kick, HR. The constant pressure from share-holders and CFOs to 'streamline' the workforce is partially to blame, but the more recent culprit is technology itself. I can't deny that the rise of technologies like virtualization, PowerCLI, PowerShell, and a host of others has been a tremendous boon. As a result, individual IT professionals are now able to handle more and more tasks and manage increasingly large and complex environments. But, without a doubt, this is a two-edged sword; The reward for competence is invariably more work. Unfortunately, SysAdmins play such a pivotal role in modern business that it's easy to see how they can very quickly become swamped in conflicting demands coming from different directions. However, that doesn't justify the ridiculous hours many are asked (or volunteer) to devote to their work. Admirably though their commitment is, it isn't healthy for them, it sets a dangerous expectation, and eventually something will snap. There are times when everyone needs to step up to the plate outside of 'normal' work hours, but that time isn't all the time. Naturally, with all that lovely technology, you can automate more and more of those tricky tasks to keep on top of the workload, but you are still only human. Clever though you may be, there is a very real limit to how far technology can take you. I'm not suggesting that you avoid these technologies, or deliberately aim for mediocrity; I'm just saying that you need to be more than just technically skilled (and Wesley Nonapeptide riffs on and around this topic in his excellent 'Telepathic Robot Drones' blog post). You need to be able to manage expectations, not just Exchange. Specifically, that means your own expectations of what you are capable of, because those come before everyone else's. After all, how can you keep your work-life balance under control, if you're the one setting the bar way too high? Talking to your manager, or discussing issues with your users, is only going to be productive if you have some facts to work with. "Know Thyself" is the first law of managing work overload, and this is obviously a skill which people develop over time; the fact that veteran Sysadmins exist at all is testament to this. I'd just love to know how you get to that point. Personally, I'm using RescueTime to keep myself honest, but I'm open to recommendations for better methods. Do you track your own time, do you have an intuitive sense of what is possible, or do you just rely on someone else to handle that all for you? Cheers, Michael

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  • Impulsioned jumping

    - by Mutoh
    There's one thing that has been puzzling me, and that is how to implement a 'faux-impulsed' jump in a platformer. If you don't know what I'm talking about, then think of the jumps of Mario, Kirby, and Quote from Cave Story. What do they have in common? Well, the height of your jump is determined by how long you keep the jump button pressed. Knowing that these character's 'impulses' are built not before their jump, as in actual physics, but rather while in mid-air - that is, you can very well lift your finger midway of the max height and it will stop, even if with desacceleration between it and the full stop; which is why you can simply tap for a hop and hold it for a long jump -, I am mesmerized by how they keep their trajetories as arcs. My current implementation works as following: While the jump button is pressed, gravity is turned off and the avatar's Y coordenate is decremented by the constant value of the gravity. For example, if things fall at Z units per tick, it will rise Z units per tick. Once the button is released or the limit is reached, the avatar desaccelerates in an amount that would make it cover X units until its speed reaches 0; once it does, it accelerates up until its speed matches gravity - sticking to the example, I could say it accelerates from 0 to Z units/tick while still covering X units. This implementation, however, makes jumps too diagonal, and unless the avatar's speed is faster than the gravity, which would make it way too fast in my current project (it moves at about 4 pixels per tick and gravity is 10 pixels per tick, at a framerate of 40FPS), it also makes it more vertical than horizontal. Those familiar with platformers would notice that the character's arc'd jump almost always allows them to jump further even if they aren't as fast as the game's gravity, and when it doesn't, if not played right, would prove itself to be very counter-intuitive. I know this because I could attest that my implementation is very annoying. Has anyone ever attempted at similar mechanics, and maybe even succeeded? I'd like to know what's behind this kind of platformer jumping. If you haven't ever had any experience with this beforehand and want to give it a go, then please, don't try to correct or enhance my explained implementation, unless I was on the right way - try to make up your solution from scratch. I don't care if you use gravity, physics or whatnot, as long as it shows how these pseudo-impulses work, it does the job. Also, I'd like its presentation to avoid a language-specific coding; like, sharing us a C++ example, or Delphi... As much as I'm using the XNA framework for my project and wouldn't mind C# stuff, I don't have much patience to read other's code, and I'm certain game developers of other languages would be interested in what we achieve here, so don't mind sticking to pseudo-code. Thank you beforehand.

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  • Somewhere to get inspiration - Pair up the creative with the tech

    - by Morten Bergfall
    I am a somewhat green developer; some work experience, last year of school. As most of you, I am constantly working on an assortment of personal projects. Since my mind often has a somewhat drifting characteristic; I am not always able to keep the projects in check. After some time they all exhibit the moral fiber of Vikings, harlots and chain-letter-knitters. This includes constant forking, round-abouting, eating of school assignments of rather mundane, and hence pretty yawn-inducing, specifications, and of course quite a bit of gathering of folder dust. Well, on to my question....is there a place, forum... or something with the purpose of linking people with ideas to the people actually being able to bring said ideas to life? Of course, I know of the professional ones, like rent-a-coder and such. And there seem to be a lot of open source projects available for participation. What I'm looking for doesn't really fit into any of those categories....the form would be somewhat like rent-a-coder, but this is ideas&inspiration, not bubble-sort-my-quarterly-for-a-buck. The possibilities for developing bonds, spicy code, and plain old fun seem quite possible.As I see it, the main benefit would be that we (that is the tech-flipside of the proverbial eCoin) get something worthwhile to do, rather than squeeze the last creative grain out of our code-heavy brains.To give it some perspective...: My last project consists of an absurd jQuery-plugin that includes animated png-robots migrating from Google Earth to drag a html-element of your choosing onto the map, where it gets color, for so to be dragged back by this poorly animated robot.... Often, the line between the creative and the tech is blurred, to say the least. I wouldn't think that would be a problem. Think someone who has developed a nifty little windows application, then sees possibility for a broader use, perhaps some sort of networking functionality. This fellow sadly lacks the skill to implememet this. So he, she or it would then seek a developer with the know-how and they could complete this project together. So, do any of you know of such a place, or can nudge in the right direction? And yes, I understand completely that I should be dedicating myself to doing school work, or applying for mundane developer positions, so please.... :-) UPDATE Sadly, I'm situated in Oslo, Norway, and the number of developers are somewhat limited...and I have had quite some ahem personality issues with the ones who are available ;-) So I feel I must go deeper; search the multitude of the web...

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  • Internal Mutation of Persistent Data Structures

    - by Greg Ros
    To clarify, when I mean use the terms persistent and immutable on a data structure, I mean that: The state of the data structure remains unchanged for its lifetime. It always holds the same data, and the same operations always produce the same results. The data structure allows Add, Remove, and similar methods that return new objects of its kind, modified as instructed, that may or may not share some of the data of the original object. However, while a data structure may seem to the user as persistent, it may do other things under the hood. To be sure, all data structures are, internally, at least somewhere, based on mutable storage. If I were to base a persistent vector on an array, and copy it whenever Add is invoked, it would still be persistent, as long as I modify only locally created arrays. However, sometimes, you can greatly increase performance by mutating a data structure under the hood. In more, say, insidious, dangerous, and destructive ways. Ways that might leave the abstraction untouched, not letting the user know anything has changed about the data structure, but being critical in the implementation level. For example, let's say that we have a class called ArrayVector implemented using an array. Whenever you invoke Add, you get a ArrayVector build on top of a newly allocated array that has an additional item. A sequence of such updates will involve n array copies and allocations. Here is an illustration: However, let's say we implement a lazy mechanism that stores all sorts of updates -- such as Add, Set, and others in a queue. In this case, each update requires constant time (adding an item to a queue), and no array allocation is involved. When a user tries to get an item in the array, all the queued modifications are applied under the hood, requiring a single array allocation and copy (since we know exactly what data the final array will hold, and how big it will be). Future get operations will be performed on an empty cache, so they will take a single operation. But in order to implement this, we need to 'switch' or mutate the internal array to the new one, and empty the cache -- a very dangerous action. However, considering that in many circumstances (most updates are going to occur in sequence, after all), this can save a lot of time and memory, it might be worth it -- you will need to ensure exclusive access to the internal state, of course. This isn't a question about the efficacy of such a data structure. It's a more general question. Is it ever acceptable to mutate the internal state of a supposedly persistent or immutable object in destructive and dangerous ways? Does performance justify it? Would you still be able to call it immutable? Oh, and could you implement this sort of laziness without mutating the data structure in the specified fashion?

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  • Dynamic character animation - Using the physics engine or not

    - by Lex Webb
    I'm planning on building a dynamic reactant animation engine for the characters in my 2D Game. I have already built templates for a skeleton based animation system using key frames and interpolation to specify a limbs position at any given moment in time. I am using Farseer physics (an extension of Box2D) in Monogame/XNA in C# My real question lies in how i go about tying this character animation into the physics engine. I have two options: Moving limbs using physics engine - applying a interpolated force to each limb (dynamic body) in order to attempt to get it to its position as donated by the skeleton animation. Moving limbs by simply changing the position of a fixed body - Updating the new position of each limb manually, attempting to take into account physics collisions. Then stepping the physics after the animation to allow for environment interaction. Each of these methods have their distinct advantages and disadvantages. Physics based movement Advantages: Possibly more natural/realistic movement Better interaction with game objects as force applying to objects colliding with characters would be calculated for me. No need to convert to dynamic bodies when reacting to projectiles/death/fighting. Disadvantages: Possible difficulty in calculating correct amount of force to move a limb a certain distance at a constant rate. Underlying character balance system would need to be created that would need to be robust enough to prevent characters falling over at the touch of a feather. Added code complexity and processing time for the above. Static Object movement Advantages: Easy to interpolate movement of limbs between game steps Moving limbs is as simple as applying a rotation to the skeleton bone. Greater control over limbs, wont need to worry about characters falling over as all animation would be pre-defined. Disadvantages: Possible unnatural movement (Depends entirely on my animation skills!) Bad physics collision reactions with physics engine (Dynamic bodies simply slide out of the way of static objects) Need to calculate collisions with physics objects and my limbs myself and apply directional forces to them. Hard to account for slopes/stairs/non standard planes when animating walking/running animations. Need to convert objects to dynamic when reacting to projectile/fighting/death physics objects. The Question! As you can see, i have thought about this extensively, i have also had Google into physics based animation and have found mostly dissertation papers! Which is filling me with sense that it may a lot more advanced than my mathematics skills. My question is mostly subjective based on my findings above/any experience you may have: Which of the above methods should i use when creating my game? I am willing to spend the time to get a physics solution working if you think it would be possible. In the end i want to provide the most satisfying experience for the gamer, as well as a robust and dynamic system i can use to animate pretty much anything i need.

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  • Microsoft Virtual Academy

    Carpe Diem It's been since a while that I could write an article for this blog but alas, I was (and still am) very busy with customer's work. Which is actually good. So, what is this article going to tell you? Well, in general, just what I already tweeted, that life is constant process of learning - especially as software craftsman. Due to an upcoming new customer project in ASP.NET I had to seize the opportunity to get my head deeper into latest available technologies, like Windows Azure and SQL Azure. I know... cloud computing and so on is not a recent development and already available since quite a while but I never any means to get myself into this since roughly two weeks ago. Microsoft Virtual Academy I can't remember exactly what guided me towards the Microsoft Virtual Academy (MVA), oh wait... Yes, it was a posting on Facebook from an old CLIP community friend. He posted a shortened URL with #MVA tag that caught my attention. Thanks for that Thomas Kuberek. After the usual sign in or registration via Live ID I was a little bit surprised that Mauritius is not an available country option... Quick mail exchange with the MVA Decan, and yeah, apologies for the missing entry. So, currently I'm learning about Microsoft products and services, and collecting points under "Not Listed Country" until Mauritius is going to be added. Hopefully soon, as MVA honors your effort with different knowledge ranks that are compared to other students with public profiles. I think it's a nice move to add some game and competition factor into the learning game. The tracks and their different modules are mainly references to publicly available material online, namely on either MSDN, TechNet, Channel9, or other Microsoft based sites. The course material therefore also varies in different media and formats, ranging from simple online articles over downloadable documents (.docx or .pdf) to Silverlight / Windows Media streams with download options. Self-assessment and students ranking Each module in a track can be finished by taking part in a self-assessment. Up to now, the assessment I did (and passed) were limited to 10 minutes available time, and consisted of six to seven questions on the module training material. Nothing too serious but it gives you a glimpse idea how Microsoft certification exams are structured. Conclusion Nothing really new but nicely gathered, assembled and presented to the MVA students. At the moment, I wouldn't dare to compare the richness and quality of those courses with professional training offers, like Pluralsight .NET Training, LearnDevNow, VTC, etc. at all, but I think that MVA has potential. Give it a try, and let me know about your opinions.

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  • how to convert avi (xvid) to mkv or mp4 (h264)

    - by bcsteeve
    Very noob when it comes to video. I'm trying to make sense of what I"m finding via Google... but its mostly Greek to me. I have a bunch of Avi files that won't play in my WD TV Play box. Mediainfo tells me they are xvid. Specs for the box show that should be fine... but digging through forums says its hit-and-miss. So I'd like to try converting them to h264 encoded MKV or mp4 files. I gather avconv is the tool, but reading the manual just has me really really confused. I tried the very basic example of: avconv -i file.avi -c copy file.mp4 it took less than 4 seconds. And it worked... sort of. It "played" in that something came up on the screen... but there was horrible artifacting and scenes would just sort of melt into each other. I want to preserve quality if possible. I'm not concerned about file size. I'm not terribly concerned with the time it takes either, provided I can do them in a batch. Can someone familiar with the process please give me a command with the options? Thank you for your help. I'm posting the mediainfo in case it helps: General Complete name : \\SERVER\Video\Public\test.avi Format : AVI Format/Info : Audio Video Interleave File size : 189 MiB Duration : 11mn 18s Overall bit rate : 2 335 Kbps Writing application : Lavf52.32.0 Video ID : 0 Format : MPEG-4 Visual Format profile : Advanced Simple@L5 Format settings, BVOP : 2 Format settings, QPel : No Format settings, GMC : No warppoints Format settings, Matrix : Default (H.263) Muxing mode : Packed bitstream Codec ID : XVID Codec ID/Hint : XviD Duration : 11mn 18s Bit rate : 2 129 Kbps Width : 720 pixels Height : 480 pixels Display aspect ratio : 16:9 Frame rate : 29.970 fps Standard : NTSC Color space : YUV Chroma subsampling : 4:2:0 Bit depth : 8 bits Scan type : Progressive Compression mode : Lossy Bits/(Pixel*Frame) : 0.206 Stream size : 172 MiB (91%) Writing library : XviD 1.2.1 (UTC 2008-12-04) Audio ID : 1 Format : MPEG Audio Format version : Version 1 Format profile : Layer 3 Mode : Joint stereo Mode extension : MS Stereo Codec ID : 55 Codec ID/Hint : MP3 Duration : 11mn 18s Bit rate mode : Constant Bit rate : 192 Kbps Channel(s) : 2 channels Sampling rate : 48.0 KHz Compression mode : Lossy Stream size : 15.5 MiB (8%) Alignment : Aligned on interleaves Interleave, duration : 24 ms (0.72 video frame)

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  • Creating a Strong Bridge to the Post PC World

    - by Webgui
    Moving from location to location requires strong roads.  When crossing a barrier though, like a body of water or valley, we are required to build a strong bridge to get us from point A to point B in a way that is fast, safe, and easy.Yet we are not talking here about driving a car or riding a bus.  As we in the computing world are evidencing the move to the post-PC era, modernizing and migrating legacy applications to harness the power of HTML5 web, cloud and mobile is one of the most difficult challenges enterprises have faced.  Constant technological changes have weakened the business value of legacy systems, which have been developed over the years through huge investments.  There are several risks of course in this move.  Do you choose to simply rewrite code of legacy apps and transform them to HTML5 one by one?  This is quite expensive (according to research firm Gartner, the cost is $6 - $26 per line of code).  Of course, the pace of the rewriting process is very slow – around 170 lines per day for each developer – which slows down business productivity in a world in which no organization can afford to fall behind.  Other questions include whether the new cloud-based apps will have the same functionality as the trusted applications that worked for you for years.  How will the user experience be affected?  And of course, what about data security?  So we are faced with the challenge of building a sturdy bridge to stabilize our move in order to allow us to confidently and easily move our legacy applications into the post-PC era.   We at Gizmox are excited to release the first downloadable Community Technology Preview (CTP) of our Instant CloudMove Transposition Studio.Developers: To download the tool, and try it out for yourself, please visit http://www.visualwebgui.com/download.aspx.The CTP is the first and only tool-based solution allowing any Microsoft Visual Studio developer to extend VB6 and .NET enterprise client/server applications into HTML5 web, cloud and mobile applications, including the ability to upgrade their code and UI while doing so.   It is the only solution to fully replicate enterprise desktop applications behavior in the post-PC era.  With Instant CloudMove, the transposed application is available on any mobile or tablet device, browser and across any client operating system. Moreover, the extended application logic and data remains on the server behind the fire-wall and therefore the application’s front end is secured-by-design.   We would love for you to try out the tool for yourselves and let us know what you think.  How are you finding the move?

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  • Introducing Agile development after traditional project inception

    - by Riggy
    About a year and a half ago, I entered a workplace that claimed to do Agile development. What I learned was that this place has adopted several agile practices (such as daily standups, sprint plannings and sprint reviews) but none of the principles (just in time / just good enough mentality, exposing failure early, rich communication). I've now been tasked with making the team more agile and I've been assured that I have complete buy-in from the devs and the business team. As a pilot program, they've given me a project that just completed 15 months of requirements gathering, has a 110 page Analysis & Design document (to be considered as "written in stone"), and where I have no access to the end users (only to the committee made up of the users' managers who won't actually be using the product). I started small, giving them a list of expected deliverables for the first 5 sprints (leaving the future sprints undefined), a list of goals for the first sprint, and I dissected the A&D doc to get enough user stories to meet the first sprint's goals. Since then, they've asked why we don't have all the requirements for all the sprints, why I haven't started working on stuff for the third sprint (which they consider more important but is based off of the deliverables of the first 2 sprints) and are pressing for even more documentation that my entire IT team considers busy-work or un-related to us (such as writing the user manual up-front, documenting all the data fields from all the sprints up front, and more "up-front" work). This has been pretty rough for me as a new project manager, but there are improvements I have effectively implemented such as scrumban for story management, pair programming, and having the business give us customer acceptance tests up front (as part of the requirements documentation). So my questions are: What can I do to more effectively introduce change to a resistant business? Are there other practices that I can introduce on the IT side to help show the business the benefits of agile? The burden of documentation is strangling us - the business still sees it as a risk management strategy instead of as a risk. What can we do to alleviate their documentation concerns and demands (specifically the quantity of documentation and their need for all of it up front)? We are in a separate building from our business, about 3 blocks away and they refuse to have their people on the project co-habitate b/c that person "won't be able to work on their other projects while they're at our building." They expect us to always go over there and to bundle our questions so that we can ask them all at once and not waste that person's time with "constant interruptions." What can we do to get richer communication from them? Any additional advice would also be appreciated. Thanks!

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  • box2d resize bodies arround point

    - by philipp
    I have a compound object, consisting of a b2Body, vector-graphics and a list polygons which describe the b2body's shapes. This object has its own transformation matrix to centralize the storage of transformations. So far everything is working quiet fine, even scaling works, but not if i scale around a point. In the initialization phase of the object it is scaled around a point. This happens in this order: transform the main matrix transform the vector graphics and the polygons recreate the b2Body After this function ran, the shapes and all the graphics are exactly where they should be, BUT: after the first steps of the b2World the graphical stuff moves away from the body. When I ran the debugger I found out that the position of the body is 0/0 the red dot shows the center of scaling. the first image shows the basic setup and the second the final position of the graphics. This distance stays constant for the rest of the simulation. If I set the position via myBody.SetPosition( sx, sy ); the whole scenario just plays a bit more distant for the origin. Any Idea how to fix this? EDIT:: I came deeper down to the problem and it lies in the fact that i must not scale the transform matrix for the b2body shapes around the center, but set the b2body's position back to the point after scaling. But how can I calculate that point? EDIT 2 :: I came ever deeper down to it, even solved it, but this is a slow solution and i hope that there is somebody who understands what formula I need. assuming to have a set polygons relative to an origin as basis shapes for a b2body: scaling the whole object around a certain point is done in the following steps: i scale everything around the center except the polygons i create a clone of the polygons matrix i scale this clone around the point i calculate dx, dy as difference of clone.tx - original.tx and clone.ty - original.ty i scale the original polygon matrix NOT around the point i recreate the body i create the fixture i set the position of the body to dx and dy done! So what i an interested in is a formula for dx and dy without cloning matrices, scaling the clone around a point, getting dx and dy and finally scale the vertex matrix.

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  • links for 2011-01-31

    - by Bob Rhubart
    Do (Software) Architects Architect? "The first question, is 'Why is architect being used as a verb?' Mirriam-Webster dictionary does not contain a definition of architect as a verb, nor do many other recognized dictionaries." -- TheCPUWizard (tags: softwarearchitecture) Oracle Business Intelligence Blog: Gartner Magic Quadrant for BI Platforms 2011 "Oracle customers indicate they deploy the Oracle Business Intelligence Suite Enterprise Edition (OBIEE) platform to support among the most complex deployments in our survey." - Gartner (tags: oracle businessintelligence gartner) Oracle BI Server Modeling, Part 1- Designing a Query Factory (Oracle BI Foundation) Bob Ertl lays the groundwork for Business Intelligence modeling concepts with a look at "the big picture of how the BI Server fits into the system, and how the CEIM controls the query processing." (tags: oracle otn businessintelligence) Tom Graves: Modelling people in enterprise-architecture Tom says: "One of the key characteristics of ‘crossing the chasm’ to a viable whole-of-enterprise architecture is the explicit inclusion of people. In short, we need to be able to model and map where people fit in relation to the architecture. But there’s a catch. A big catch." (tags: entarch) Java developer webcasts for customers and partners (SOA Partner Community Blog) Jurgen Kress shares info on several upcoming online events focused on WebLogic. (tags: weblogic oracle otn soa) Business SOA: Data Services are bogus, Information services are real Steve Jones says: "The other day when I was talking about MDM a bright spark pointed out that I hated data services but wasn't MDM just about data services?" (tags: SOA MDM) Andrejus Baranovskis's Blog: Configuring Missing Contribution Folders for Oracle UCM 11g and WebCenter 11g PS3 Andrejus says: "After doing some research on UCM, we found that Folders_g component must be configured in UCM, for Contribution Folders to be enabled." (tags: oracle otn oracleace UCM webcenter enterprise2.0) Wim Coekaerts: Converting an Oracle VM VirtualBox VM into an Oracle VM Server image Wim Coekaerts offers a few simple steps to convert an existing Oracle VM VirtualBox image.  (tags: oracle otn virtualization virtualbox) Stefan Hinker: Secure Deployment of Oracle VM Server for SPARC This new paper from Stefan Hinker will help you understand the general security concerns in virtualized environments as well as the specific additional threats that arise out of them. (tags: oracle otn SPARC virtualization enterprisearchitecture) The EA Roadmap to Rationalize, Standardize, and Consolidate the IT Portfolio Enterprise IT is in a state of constant evolution. As a result, business processes and technologies become increasingly more difficult to change and more costly to keep up-to-date. (tags: entarch oracle otn)

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  • Simulating smooth movement along a line after calculating a collision containing a restitution of zero in 2D

    - by Casey
    [for tl;dr see after listing] //...Code to determine shapes types involved in collision here... //...Rectangle-Line collision detected. if(_rbTest->GetCollisionShape()->Intersects(*_ground->GetCollisionShape())) { //Convert incoming shape to a line. a2de::Line l(*dynamic_cast<a2de::Line*>(_ground->GetCollisionShape())); //Get line's normal. a2de::Vector2D normal_vector(l.GetSlope().GetY(), -l.GetSlope().GetX()); a2de::Vector2D::Normalize(normal_vector); //Accumulate forces involved. a2de::Vector2D intermediate_forces; a2de::Vector2D normal_force = normal_vector * _rbTest->GetMass() * _world->GetGravityHandler()->GetGravityValue(); intermediate_forces += normal_force; //Calculate final velocity: See [1] double Ma = _rbTest->GetMass(); a2de::Vector2D Ua = _rbTest->GetVelocity(); double Mb = _ground->GetMass(); a2de::Vector2D Ub = _ground->GetVelocity(); double mCr = Mb * _ground->GetRestitution(); a2de::Vector2D collision_velocity( ((Ma * Ua) + (Mb * Ub) + ((mCr * Ub) - (mCr * Ua))) / (Ma + Mb)); //Calculate reflection vector: See [2] a2de::Vector2D reflect_velocity( -collision_velocity + 2 * (a2de::Vector2D::DotProduct(collision_velocity, normal_vector)) * normal_vector ); //Affect velocity to account for restitution of colliding bodies. reflect_velocity *= (_ground->GetRestitution() * _rbTest->GetRestitution()); _rbTest->SetVelocity(reflect_velocity); //THE ULTIMATE ISSUE STEMS FROM THE FOLLOWING LINE: //Move object away from collision one pixel to prevent constant collision. _rbTest->SetPosition(_rbTest->GetPosition() + normal_vector); _rbTest->ApplyImpulse(intermediate_forces); } Sources: (1) Wikipedia: Coefficient of Restitution: Speeds after impact (2) Wikipedia: Specular Reflection: Direction of reflection First, I have a system in place to account for friction (that is, a coefficient of friction) but is not used right now (in addition, it is zero, which should not affect the math anyway). I'll deal with that after I get this working. Anyway, when the restitution of either object involved in the collision is zero the object stops as required, but if movement along the same direction (again, irrespective of the friction value that isn't used) as the line is attempted the object moves as if slogging through knee deep snow. If I remove the line of code in question and the object is not push away one pixel the object barely moves at all. All because the object collides, is stopped, is pushed up, collides, is stopped...etc. OR collides, is stopped, collides, is stopped, etc... TL;DR How do I only account for a collision ONCE for restitution purposes (BONUS: but CONTINUALLY for frictional purposes, to be implemented later)

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  • Retail in New York - a walk down 5th Avenue

    - by sarah.taylor(at)oracle.com
    It's the week of the NRF Big Show and all eyes in the retail industry are on New York. The Big Apple is famous for Big Retail -with a proliferation of incredibly iconic stores. The environment is exciting and familiar even to people visiting this small island for the first time. Most of us have travelled down Fifth Avenue watching movies and TV even if we have never set foot on American soil. I find it one of the most exciting retail cities in the world and I am thrilled this year to be here with so many of Oracle's International retail customers who are joining us for the Retail Exchange. The Oracle program brings retailers from all over the planet together to share ideas and be inspired by New York retail and the NRF event. The show celebrates its 100th year in 2011 and New York itself has been recognized globally as the capital of innovative retail for just as long.  Fifth Avenue is where many global brands have placed their flagship stores, and businesses are in constant competition to set themselves apart from their competitors - both in the store and from the street.  These flag ship retail destinations present what today's customers are finding most exciting and delightful about retail. For the tourist market, they may only visit these stores once, but the impression that a trip to a flagship store leaves with a customer can last a lifetime.  One of the stores that is currently turning heads on Fifth Avenue is Hollister, sister brand to Abercrombie and Fitch, which has filled its shop front with a massive live video (and audio) feed of surfers on the beach in California.  To complete the effect, they also have troughs of water in front of the video screens to bring the sea to the street.  And this isn't the only kind of surfing that retailers are considering today and multi-channel retail is a hot topic that all of the retailers joining the Retail Exchange are considering.   The rest of the world looks to the brands along Fifth Avenue for inspiration - how they take advantage of new opportunities, how they set themselves apart from their competitors and how they keep their products fresh and desirable. With these inspiring pioneers in New York, it's little wonder that NRF's Big Show is so popular, and that New York is viewed as one of the retail capitals of the world. It is a pleasure to be here with so many of the world's greatest international retailers.

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  • What are some reasonable stylistic limits on type inference?

    - by Jon Purdy
    C++0x adds pretty darn comprehensive type inference support. I'm sorely tempted to use it everywhere possible to avoid undue repetition, but I'm wondering if removing explicit type information all over the place is such a good idea. Consider this rather contrived example: Foo.h: #include <set> class Foo { private: static std::set<Foo*> instances; public: Foo(); ~Foo(); // What does it return? Who cares! Just forward it! static decltype(instances.begin()) begin() { return instances.begin(); } static decltype(instances.end()) end() { return instances.end(); } }; Foo.cpp: #include <Foo.h> #include <Bar.h> // The type need only be specified in one location! // But I do have to open the header to find out what it actually is. decltype(Foo::instances) Foo::instances; Foo() { // What is the type of x? auto x = Bar::get_something(); // What does do_something() return? auto y = x.do_something(*this); // Well, it's convertible to bool somehow... if (!y) throw "a constant, old school"; instances.insert(this); } ~Foo() { instances.erase(this); } Would you say this is reasonable, or is it completely ridiculous? After all, especially if you're used to developing in a dynamic language, you don't really need to care all that much about the types of things, and can trust that the compiler will catch any egregious abuses of the type system. But for those of you that rely on editor support for method signatures, you're out of luck, so using this style in a library interface is probably really bad practice. I find that writing things with all possible types implicit actually makes my code a lot easier for me to follow, because it removes nearly all of the usual clutter of C++. Your mileage may, of course, vary, and that's what I'm interested in hearing about. What are the specific advantages and disadvantages to radical use of type inference?

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  • Gauging Maturity of your BPM Strategy - part 1 / 2

    - by Sanjeev Sharma
    Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman","serif";} In this post I will discuss the essence of maturity assessment and the business imperative for doing the same in the context of BPM. Social psychology purports that an individual progresses from being a beginner to an expert in a given activity or task along four stages of self-awareness: Unconscious Incompetence where the individual does not understand or know how to do something and does not necessarily recognize the deficit and may even deny the usefulness of the skill. Conscious Incompetence where the individual recognizes the deficit, as well as the value of a new skill in addressing the deficit. Conscious Competence where the individual understands or knows how to do something but demonstrating the skill requires explicit concentration. Unconscious Competence where the individual has had so much practice with a skill that it has become "second nature" and serves as a basis of developing other complementary skills. We can extend the above thinking to an organization as a whole by measuring an organization’s level of competence in a specific area or capability, as an aggregate of the competence levels of individuals it is comprised of. After all organizations too like individuals, evolve through experience, develop “memory” and capabilities that are shaped through a constant cycle of learning, un-learning and re-learning. Hence the key to organizational success lies in developing these capabilities to enable execution of its strategy in-line with the external environment i.e. demand, competition, economy etc. However developing a capability merits establishing a base line in order to Assess the magnitude of improvement from past investments Identify gaps and short-comings Prioritize future investments in the right areas A maturity assessment is essentially an organizational self-awareness check that is aimed at depicting the “as-is” snapshot of an existing capability in-order to guide future investments to develop that capability in-line with business goals. This effectively is the essence of a maturity Organizational capabilities stem through its architecture, routines, culture and intellectual resources that are implicitly and explicitly embedded in its business processes. Given that business processes underpin realization of organizational capabilities, is what has prompted business transformation and process management efforts. Thus, the BPM capability of an organization needs to be measured on an on-going basis to ensure delivery of its planned benefits. In my next post I will describe Oracle’s BPM Maturity assessment methodology.

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  • Lubuntu wireless issue with Broadcom chipset

    - by Variant Web Solutions
    I'm a web dev that just started a new venture in buying wiped laptops in bulk and selling them at a low cost to lower income families that want a laptop that will simply preform and not become virus ridden and require constant maintenance, so naturally I opted for a linux distro and after some research, lubuntu was my top pick. I'm not a stranger to linux as all of my servers for my web dev business are linux, but I am however new to L/Ubuntu and I'm having some issues with both wifi (broadcom chipsets) on the 20 or so dells that I have right now, D800's, D810's and E5400's. Not sure if you can point me in a solid direction, I've scoured (and implemented) the suggestions on ask ubuntu and still coming up short. On one of the e5400's ( though they all seem to suffer the same errors) I got the following: [code]dell-latitude-e5400@dell-Latitude-E5400:~$ iwconfig lo no wireless extensions. eth0 no wireless extensions. dell-latitude-e5400@dell-Latitude-E5400:~$ lspci 00:00.0 Host bridge: Intel Corporation Mobile 4 Series Chipset Memory Controller Hub (rev 07) 00:02.0 VGA compatible controller: Intel Corporation Mobile 4 Series Chipset Integrated Graphics Controller (rev 07) 00:02.1 Display controller: Intel Corporation Mobile 4 Series Chipset Integrated Graphics Controller (rev 07) 00:1a.0 USB controller: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #4 (rev 02) 00:1a.1 USB controller: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #5 (rev 02) 00:1a.2 USB controller: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #6 (rev 02) 00:1a.7 USB controller: Intel Corporation 82801I (ICH9 Family) USB2 EHCI Controller #2 (rev 02) 00:1b.0 Audio device: Intel Corporation 82801I (ICH9 Family) HD Audio Controller (rev 02) 00:1c.0 PCI bridge: Intel Corporation 82801I (ICH9 Family) PCI Express Port 1 (rev 02) 00:1c.1 PCI bridge: Intel Corporation 82801I (ICH9 Family) PCI Express Port 2 (rev 02) 00:1c.4 PCI bridge: Intel Corporation 82801I (ICH9 Family) PCI Express Port 5 (rev 02) 00:1d.0 USB controller: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #1 (rev 02) 00:1d.1 USB controller: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #2 (rev 02) 00:1d.2 USB controller: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #3 (rev 02) 00:1d.7 USB controller: Intel Corporation 82801I (ICH9 Family) USB2 EHCI Controller #1 (rev 02) 00:1e.0 PCI bridge: Intel Corporation 82801 Mobile PCI Bridge (rev 92) 00:1f.0 ISA bridge: Intel Corporation ICH9M LPC Interface Controller (rev 02) 00:1f.2 IDE interface: Intel Corporation 82801IBM/IEM (ICH9M/ICH9M-E) 2 port SATA Controller [IDE mode] (rev 02) 00:1f.3 SMBus: Intel Corporation 82801I (ICH9 Family) SMBus Controller (rev 02) 00:1f.5 IDE interface: Intel Corporation 82801IBM/IEM (ICH9M/ICH9M-E) 2 port SATA Controller [IDE mode] (rev 02) 02:01.0 CardBus bridge: Ricoh Co Ltd RL5c476 II (rev ba) 02:01.1 FireWire (IEEE 1394): Ricoh Co Ltd R5C832 IEEE 1394 Controller (rev 04) 02:01.2 SD Host controller: Ricoh Co Ltd R5C822 SD/SDIO/MMC/MS/MSPro Host Adapter (rev 21) 09:00.0 Ethernet controller: Broadcom Corporation NetXtreme BCM5761e Gigabit Ethernet PCIe (rev 10) dell-latitude-e5400@dell-Latitude-E5400:~$ rfkill Usage: rfkill [options] command Options: --version show version (0.5-1ubuntu1 (Ubuntu)) Commands: help event list [IDENTIFIER] block IDENTIFIER unblock IDENTIFIER where IDENTIFIER is the index no. of an rfkill switch or one of: all wifi wlan bluetooth uwb ultrawideband wimax wwan gps fm nfc dell-latitude-e5400@dell-Latitude-E5400:~$ [/code]

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  • How to remove the boundary effects arising due to zero padding in scipy/numpy fft?

    - by Omkar
    I have made a python code to smoothen a given signal using the Weierstrass transform, which is basically the convolution of a normalised gaussian with a signal. The code is as follows: #Importing relevant libraries from __future__ import division from scipy.signal import fftconvolve import numpy as np def smooth_func(sig, x, t= 0.002): N = len(x) x1 = x[-1] x0 = x[0] # defining a new array y which is symmetric around zero, to make the gaussian symmetric. y = np.linspace(-(x1-x0)/2, (x1-x0)/2, N) #gaussian centered around zero. gaus = np.exp(-y**(2)/t) #using fftconvolve to speed up the convolution; gaus.sum() is the normalization constant. return fftconvolve(sig, gaus/gaus.sum(), mode='same') If I run this code for say a step function, it smoothens the corner, but at the boundary it interprets another corner and smoothens that too, as a result giving unnecessary behaviour at the boundary. I explain this with a figure shown in the link below. Boundary effects This problem does not arise if we directly integrate to find convolution. Hence the problem is not in Weierstrass transform, and hence the problem is in the fftconvolve function of scipy. To understand why this problem arises we first need to understand the working of fftconvolve in scipy. The fftconvolve function basically uses the convolution theorem to speed up the computation. In short it says: convolution(int1,int2)=ifft(fft(int1)*fft(int2)) If we directly apply this theorem we dont get the desired result. To get the desired result we need to take the fft on a array double the size of max(int1,int2). But this leads to the undesired boundary effects. This is because in the fft code, if size(int) is greater than the size(over which to take fft) it zero pads the input and then takes the fft. This zero padding is exactly what is responsible for the undesired boundary effects. Can you suggest a way to remove this boundary effects? I have tried to remove it by a simple trick. After smoothening the function I am compairing the value of the smoothened signal with the original signal near the boundaries and if they dont match I replace the value of the smoothened func with the input signal at that point. It is as follows: i = 0 eps=1e-3 while abs(smooth[i]-sig[i])> eps: #compairing the signals on the left boundary smooth[i] = sig[i] i = i + 1 j = -1 while abs(smooth[j]-sig[j])> eps: # compairing on the right boundary. smooth[j] = sig[j] j = j - 1 There is a problem with this method, because of using an epsilon there are small jumps in the smoothened function, as shown below: jumps in the smooth func Can there be any changes made in the above method to solve this boundary problem?

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