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• Launch 7:Windows Phone 7 Style Live Tiles On Android Mobiles

  - by Gopinath

  Android is a great mobile OS but one thought that lingers in the mind of few Android owners is: Am I using a cheap iPhone? This is valid thought for many low end Android users as their phones runs sluggish and the user interface of Android looks like an imitation of iOS. When it comes to Windows Phone 7 users, even though their operating system features are not as great as iPhone/Android but it has its unique user interface; Windows Phone 7 user interface is a very intuitive and fresh, it’s constantly updating Live Tiles show all the required information on the home screen. Android has best mobile operating system features except UI and Windows Phone 7 has excellent user interface. How about porting Windows Phone 7 Tiles interface on an Android? That should be great. Launch 7 app brings the best of Windows Phone 7 look and feel to Android OS. Once the Launcher 7 app is installed and activated, it brings Live Tiles or constantly updating controls that show information on Android home screen. Apart from simple and smooth tiles, there are handful of customization options provided. Users can change colour of the tiles, add new tiles, enable/disable transitions. The reviews on Android Market are on the positive side with 4.4 stars by 10,000 + reviewers. Here are few user reviews 1. Does what it says. only issue for me is that the app drawer doesn’t rotate. And I would like the UI to rotate when my KB is opened. HTC desire z – Jonathan 2. Works great on atrix.Kudos to developers. Awesome. Though needs: Better notification bar More stock images of tiles Better fitting of widgets on tiles – Manny 3. Looks really good like it much more than I thought I would runs real smooth running royal ginger 2.1 – Jay 4. Omg amazing i am definetly keeping it as my default best of android and windows – Devon 5. Man! An update every week! Very very responsive developer! – Andrew You can read more reviews on Android Market here.  There is no doubt that this application is receiving rave reviews. After scanning a while through the reviews, few complaints throw light on the negative side: Battery drains a bit faster & Low end mobile run a bit sluggish. The application is available in two versions – an ad supported free version and $1.41 ad free version. Download Launcher 7 from Android Market This article titled,Launch 7:Windows Phone 7 Style Live Tiles On Android Mobiles, was originally published at Tech Dreams. Grab our rss feed or fan us on Facebook to get updates from us.

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• What DX level does my graphics card support? Does it go to 11?

  - by Daniel Moth

  Recently I run into a situation that I have run into quite a few times. Someone encounters a machine and the question arises: "Is there a DirectX 11 card in this machine?". Typically the reason you are interested in that is because cards with DirectX 11 drivers fully support DirectCompute (and by extension C++ AMP) for GPGPU programming. The driver specifically is WDDM (1.1 on Windows 7 and Windows 8 introduces WDDM 1.2 with cool new capabilities). There are many ways for figuring out if you have a DirectX11 card, so here are the approaches that you can use, with a bonus right at the end of the post. Run DxDiag WindowsKey + R, type DxDiag and hit Enter. That is the DirectX diagnostic tool, which unfortunately, only tells you on the "System" tab what is the highest version of DirectX installed on your machine. So if it reports DirectX 11, that doesn't mean you have a DX11 driver! The "Display" tab has a promising "DDI version" label, but unfortunately that doesn't seem to be accurate on the machines I've tested it with (or I may be misinterpreting its use). Either way, this tool is not the one you want for this purpose, although it is good for telling you the WDDM version among other things. Use the Microsoft hardware page There is a Microsoft Windows 7 compatibility center, that lists all hardware (tip: use the advanced search) and you could try and locate your device there… good luck. Use Wikipedia or the hardware vendor's website Use the Wikipedia page for the vendor cards, for both nvidia and amd. Often this information will also be in the specifications for the cards on the IHV site, but is is nice that wikipedia has a single page per vendor that you can search etc. There is a column in the tables for API support where you can see the DirectX version. Check if it is one of these recommended DX11 cards You may not have a DirectX 11 card and are interested in purchasing one. While I am in no position to make recommendations, I will list here some cards from two big IHVs that we know are DirectX 11 capable. Some AMD (aka ATI) cards Low end, inexpensive DX11 hardware: Radeon 5450, 5550, 6450, 6570 Mid range (decent perf, single precision): Radeon 5750, 5770, 6770, 6790 High end (capable of double precision): Radeon 5850, 5870, 6950, 6970 Single precision APUs: AMD E-Series APUs AMD A-Series APUs Some NVIDIA cards Low end, inexpensive DX11 hardware: GeForce GT430, GT 440, GT520, GTS 450 Quadro 400, 600 Mid-range (decent perf, single precision): GeForce GTX 460, GTX 550 Ti, GTX 560, GTX 560 Ti Quadro 2000 High end (capable of double precision): GeForce GTX 480, GTX 570, GTX 580, GTX 590, GTX 595 Quadro 4000, 5000, 6000 Tesla C2050, C2070, C2075 Get the DirectX SDK and run DirectX Caps Viewer Download and install the June 2010 DirectX SDK. As part of that you now have the DirectX Capabilities Viewer utility (find it in your start menu by searching for "DirectX Caps Viewer", the filename is DXCapsViewer.exe). It will list all your devices (emulated, and real hardware ones) under the first node. Expand the hardware entries and then expand again the Direct3D 11 folder. If you see D3D_FEATURE_LEVEL_11_ under that, then your card supports feature level 11 which means it supports DirectCompute and C++ AMP. In the following screenshot of one of my old laptops, the card only goes to feature level 10. Run a utility from the web that just tells you! Of course, writing some C++ AMP code that enumerates accelerators and lists the ones that are capable is trivial. However that requires that you have redistributed the runtime, so a more broadly applicable approach is to use the DX APIs directly to enumerate the DX11 capable cards. That is exactly what the development lead for C++ AMP has done and he describes and shares that utility at this post. Comments about this post by Daniel Moth welcome at the original blog.

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• Mind Reading with the Raspberry Pi

  - by speakjava

  Mind Reading With The Raspberry Pi At JavaOne in San Francisco I did a session entitled "Do You Like Coffee with Your Dessert? Java and the Raspberry Pi".  As part of this I showed some demonstrations of things I'd done using Java on the Raspberry Pi.  This is the first part of a series of blog entries that will cover all the different aspects of these demonstrations. A while ago I had bought a MindWave headset from Neurosky.  I was particularly interested to see how this worked as I had had the opportunity to visit Neurosky several years ago when they were still developing this technology.  At that time the 'headset' consisted of a headband (very much in the Bjorn Borg style) with a sensor attached and some wiring that clearly wasn't quite production ready.  The commercial version is very simple and easy to use: there are two sensors, one which rests on the skin of your forehead, the other is a small clip that attaches to your earlobe. Typical EEG sensors used in hospitals require lots of sensors and they all need copious amounts of conductive gel to ensure the electrical signals are picked up.  Part of Neurosky's innovation is the development of this simple dry-sensor technology.  Having put on the sensor and turned it on (it powers off a single AAA size battery) it collects data and transmits it to a USB dongle plugged into a PC, or in my case a Raspberry Pi. From a hacking perspective the USB dongle is ideal because it does not require any special drivers for any complex, low level USB communication.  Instead it appears as a simple serial device, which on the Raspberry Pi is accessed as /dev/ttyUSB0.  Neurosky have published details of the command protocol.  In addition, the MindSet protocol document, including sample code for parsing the data from the headset, can be found here. To get everything working on the Raspberry Pi using Java the first thing was to get serial communications going.  Back in the dim distant past there was the Java Comm API.  Sadly this has grown a bit dusty over the years, but there is a more modern open source project that provides compatible and enhanced functionality, RXTXComm.  This can be installed easily on the Pi using sudo apt-get install librxtx-java.  Next I wrote a library that would send commands to the MindWave headset via the serial port dongle and read back data being sent from the headset.  The design is pretty simple, I used an event based system so that code using the library could register listeners for different types of events from the headset.  You can download a complete NetBeans project for this here.  This includes javadoc API documentation that should make it obvious how to use it (incidentally, this will work on platforms other than Linux.  I've tested it on Windows without any issues, just by changing the device name to something like COM4). To test this I wrote a simple application that would connect to the headset and then print the attention and meditation values as they were received from the headset.  Again, you can download the NetBeans project for that here. Oracle recently released a developer preview of JavaFX on ARM which will run on the Raspberry Pi.  I thought it would be cool to write a graphical front end for the MindWave data that could take advantage of the built in charts of JavaFX.  Yet another NetBeans project is available here.  Screen shots of the app, which uses a very nice dial from the JFxtras project, are shown below. I probably should add labels for the EEG data so the user knows which is the low alpha, mid gamma waves and so on.  Given that I'm not a neurologist I suspect that it won't increase my understanding of what the (rather random looking) traces mean. In the next blog I'll explain how I connected a LEGO motor to the GPIO pins on the Raspberry Pi and then used my mind to control the motor!

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• What DX level does my graphics card support? Does it go to 11?

  - by Daniel Moth

  Recently I run into a situation that I have run into quite a few times. Someone encounters a machine and the question arises: "Is there a DirectX 11 card in this machine?". Typically the reason you are interested in that is because cards with DirectX 11 drivers fully support DirectCompute (and by extension C++ AMP) for GPGPU programming. The driver specifically is WDDM (1.1 on Windows 7 and Windows 8 introduces WDDM 1.2 with cool new capabilities). There are many ways for figuring out if you have a DirectX11 card, so here are the approaches that you can use, with a bonus right at the end of the post. Run DxDiag WindowsKey + R, type DxDiag and hit Enter. That is the DirectX diagnostic tool, which unfortunately, only tells you on the "System" tab what is the highest version of DirectX installed on your machine. So if it reports DirectX 11, that doesn't mean you have a DX11 driver! The "Display" tab has a promising "DDI version" label, but unfortunately that doesn't seem to be accurate on the machines I've tested it with (or I may be misinterpreting its use). Either way, this tool is not the one you want for this purpose, although it is good for telling you the WDDM version among other things. Use the Microsoft hardware page There is a Microsoft Windows 7 compatibility center, that lists all hardware (tip: use the advanced search) and you could try and locate your device there… good luck. Use Wikipedia or the hardware vendor's website Use the Wikipedia page for the vendor cards, for both nvidia and amd. Often this information will also be in the specifications for the cards on the IHV site, but is is nice that wikipedia has a single page per vendor that you can search etc. There is a column in the tables for API support where you can see the DirectX version. Check if it is one of these recommended DX11 cards You may not have a DirectX 11 card and are interested in purchasing one. While I am in no position to make recommendations, I will list here some cards from two big IHVs that we know are DirectX 11 capable. Some AMD (aka ATI) cards Low end, inexpensive DX11 hardware: Radeon 5450, 5550, 6450, 6570 Mid range (decent perf, single precision): Radeon 5750, 5770, 6770, 6790 High end (capable of double precision): Radeon 5850, 5870, 6950, 6970 Single precision APUs: AMD E-Series APUs AMD A-Series APUs Some NVIDIA cards Low end, inexpensive DX11 hardware: GeForce GT430, GT 440, GT520, GTS 450 Quadro 400, 600 Mid-range (decent perf, single precision): GeForce GTX 460, GTX 550 Ti, GTX 560, GTX 560 Ti Quadro 2000 High end (capable of double precision): GeForce GTX 480, GTX 570, GTX 580, GTX 590, GTX 595 Quadro 4000, 5000, 6000 Tesla C2050, C2070, C2075 Get the DirectX SDK and run DirectX Caps Viewer Download and install the June 2010 DirectX SDK. As part of that you now have the DirectX Capabilities Viewer utility (find it in your start menu by searching for "DirectX Caps Viewer", the filename is DXCapsViewer.exe). It will list all your devices (emulated, and real hardware ones) under the first node. Expand the hardware entries and then expand again the Direct3D 11 folder. If you see D3D_FEATURE_LEVEL_11_ under that, then your card supports feature level 11 which means it supports DirectCompute and C++ AMP. In the following screenshot of one of my old laptops, the card only goes to feature level 10. Run a utility from the web that just tells you! Of course, writing some C++ AMP code that enumerates accelerators and lists the ones that are capable is trivial. However that requires that you have redistributed the runtime, so a more broadly applicable approach is to use the DX APIs directly to enumerate the DX11 capable cards. That is exactly what the development lead for C++ AMP has done and he describes and shares that utility at this post. Comments about this post by Daniel Moth welcome at the original blog.

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• Best Practices - Core allocation

  - by jsavit

  This post is one of a series of "best practices" notes for Oracle VM Server for SPARC (also called Logical Domains) Introduction SPARC T-series servers currently have up to 4 CPU sockets, each of which has up to 8 or (on SPARC T3) 16 CPU cores, while each CPU core has 8 threads, for a maximum of 512 dispatchable CPUs. The defining feature of Oracle VM Server for SPARC is that each domain is assigned CPU threads or cores for its exclusive use. This avoids the overhead of software-based time-slicing and emulation (or binary rewriting) of system state-changing privileged instructions used in traditional hypervisors. To create a domain, administrators specify either the number of CPU threads or cores that the domain will own, as well as its memory and I/O resources. When CPU resources are assigned at the individual thread level, the logical domains constraint manager attempts to assign threads from the same cores to a domain, and avoid "split core" situations where the same CPU core is used by multiple domains. Sometimes this is unavoidable, especially when domains are allocated and deallocated CPUs in small increments. Why split cores can matter Split core allocations can silenty reduce performance because multiple domains with different address spaces and memory contents are sharing the core's Level 1 cache (L1$). This is called false cache sharing since even identical memory addresses from different domains must point to different locations in RAM. The effect of this is increased contention for the cache, and higher memory latency for each domain using that core. The degree of performance impact can be widely variable. For applications with very small memory working sets, and with I/O bound or low-CPU utilization workloads, it may not matter at all: all machines wait for work at the same speed. If the domains have substantial workloads, or are critical to performance then this can have an important impact: This blog entry was inspired by a customer issue in which one CPU core was split among 3 domains, one of which was the control and service domain. The reported problem was increased I/O latency in guest domains, but the root cause might be higher latency servicing the I/O requests due to the control domain being slowed down. What to do about it Split core situations are easily avoided. In most cases the logical domain constraint manager will avoid it without any administrative action, but it can be entirely prevented by doing one of the several actions: Assign virtual CPUs in multiples of 8 - the number of threads per core. For example: ldm set-vcpu 8 mydomain or ldm add-vcpu 24 mydomain. Each domain will then be allocated on a core boundary. Use the whole core constraint when assigning CPU resources. This allocates CPUs in increments of entire cores instead of virtual CPU threads. The equivalent of the above commands would be ldm set-core 1 mydomain or ldm add-core 3 mydomain. Older syntax does the same thing by adding the -c flag to the add-vcpu, rm-vcpu and set-vcpu commands, but the new syntax is recommended. When whole core allocation is used an attempt to add cores to a domain fails if there aren't enough completely empty cores to satisfy the request. See https://blogs.oracle.com/sharakan/entry/oracle_vm_server_for_sparc4 for an excellent article on this topic by Eric Sharakan. Don't obsess: - if the workloads have minimal CPU requirements and don't need anywhere near a full CPU core, then don't worry about it. If you have low utilization workloads being consolidated from older machines onto a current T-series, then there's no need to worry about this or to assign an entire core to domains that will never use that much capacity. In any case, make sure the most important domains have their own CPU cores, in particular the control domain and any I/O or service domain, and of course any important guests. Summary Split core CPU allocation to domains can potentially have an impact on performance, but the logical domains manager tends to prevent this situation, and it can be completely and simply avoided by allocating virtual CPUs on core boundaries.

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• what differs a computer scientist/software engineer to regular people who learn programming language and APIs?

  - by Amumu

  In University, we learn and reinvent the wheel a lot to truly learn the programming concepts. For example, we may learn assembly language to understand, what happens inside the box, and how the system operates, when we execute our code. This helps understanding higher level concepts deeper. For example, memory management like in C is just an abstraction of manually managed memory contents and addresses. The problem is, when we're going to work, usually productivity is required more. I could program my own containers, or string class, or date/time (using POSIX with C system call) to do the job, but then, it would take much longer time to use existing STL or Boost library, which abstract all of those thing and very easy to use. This leads to an issue, that a regular person doesn't need to get through all the low level/under the hood stuffs, who learns only one programming language and using language-related APIs. These people may eventually compete with the mainstream graduates from computer science or software engineer and call themselves programmers. At first, I don't think it's valid to call them programmers. I used to think, a real programmer needs to understand the computer deeply (but not at the electronic level). But then I changed my mind. After all, they get the job done and satisfy all the test criteria (logic, performance, security...), and in business environment, who cares if you're an expert and understand how computer works or not. You may get behind the "amateurs" if you spend to much time learning about how things work inside. It is totally valid for those people to call themselves programmers. This makes me confuse. So, after all, programming should be considered an universal skill? Does programming language and concepts matter or the problems we solve matter? For example, many C/C++ vs Java and other high level language, one of the main reason is because C/C++ features performance, as well as accessing low level facility. One of the main reason (in my opinion), is coding in C/C++ seems complex, so people feel good about it (not trolling anyone, just my observation, and my experience as well. Try to google "C hacker syndrome"). While Java on the other hand, made for simplifying programming tasks to help developers concentrate on solving their problems. Based on Java rationale, if the programing language keeps evolve, one day everyone can map their logic directly with natural language. Everyone can program. On that day, maybe real programmers are mathematicians, who could perform most complex logic (including business logic and academic logic) without worrying about installing/configuring compiler, IDEs? What's our job as a computer scientist/software engineer? To solve computer specific problems or to solve problems in general? For example, take a look at this exame: http://cm.baylor.edu/ICPCWiki/attach/Problem%20Resources/2010WorldFinalProblemSet.pdf . The example requires only basic knowledge about the programming language, but focus more on problem solving with the language. In sum, what differs a computer scientist/software engineer to regular people who learn programming language and APIs? A mathematician can be considered a programmer, if he is good enough to use programming language to implement his formula. Can we programmer do this? Probably not for most of us, since we specialize about computer, not math. An electronic engineer, who learns how to use C to program for his devices, can be considered a programmer. If the programming languages keep being simplified, may one day the software engineers, who implements business logic and create softwares, be obsolete? (Not for computer scientist though, since many of the CS topics are scientific, and science won't change, but technology will).

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• Reaching to the Holy Grail of Data Management

  - by Irem Radzik

  Pervasive, continuous access to trusted data. That’s the ultimate goal of data management. It enables to leverage data as an asset to create value for customers and the organization. It creates the strong foundation needed to move the business forward. How you get there is also critical. As with all IT initiatives using high performance solutions with low cost of ownership is another key requirement in today’s IT world. Oracle's  data integration product strategy focuses on helping customers achieve this ultimate goal with high performance and low TCO.  At OpenWorld, we will be showing how Oracle Data Integration products help you reach your data management goals, considering new trends in information management, such as big data and cloud computing. We will also provide an update on the latest product releases, such as Oracle GoldenGate 11gR2. If you will be at OpenWorld, please join us on Monday Oct 1st 10:45am at Moscone West – 3005 to hear our VP of Product Development, Brad Adelberg, present "Future Strategy, Direction, and Roadmap of Oracle’s Data Integration Platform". The Data Integration track at OpenWorld covers variety of topics and speakers. In addition to product management of Oracle GoldenGate, Oracle Data Integrator, and Enteprise Data Quality presenting product updates and roadmap, we have several customer panels and stand-alone sessions featuring select customers such as St. Jude Medical, Raymond James, Aderas, Turkcell, Paychex, Comcast,  Ticketmaster, Bank of America and more. You can see an overview of Data Integration sessions here. If you are not able to attend OpenWorld, please check out our latest resources for Data Integration and Oracle GoldenGate. In the coming weeks you will see more blogs about our products’ new capabilities and what to expect at OpenWorld. I hope to see you at OpenWorld and stay in touch via our future blogs. 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-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin;}

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• The Minimalist Approach to Content Governance - Request Phase

  - by Kellsey Ruppel

  Originally posted by John Brunswick. For each project, regardless of size, it is critical to understand the required ownership, business purpose, prerequisite education / resources needed to execute and success criteria around it. Without doing this, there is no way to get a handle on the content life-cyle, resulting in a mass of orphaned material. This lowers the quality of end user experiences.     The good news is that by using a simple process in this request phase - we will not have to revisit this phase unless something drastic changes in the project. For each of the elements mentioned above in this stage, the why, how (technically focused) and impact are outlined with the intent of providing the most value to a small team. 1. Ownership Why - Without ownership information it will not be possible to track and manage any of the content and take advantage of many features of enterprise content management technology. To hedge against this, we need to ensure that both a individual and their group or department within the organization are associated with the content. How - Apply metadata that indicates the owner and department or group that has responsibility for the content. Impact - It is possible to keep the content system optimized by running native reports against the meta-data and acting on them based on what has been outlined for success criteria. This will maximize end user experience, as content will be faster to locate and more relevant to the user by virtue of working through a smaller collection. 2. Business Purpose Why - This simple step will weed out requests that have tepid justification, as users will most likely not spend the effort to request resources if they do not have a real need. How - Use a simple online form to collect and workflow the request to management native to the content system. Impact - Minimizes the amount user generated content that is of low value to the organization. 3. Prerequisite Education Resources Needed Why - If a project cannot be properly staffed the probability of its success is going to be low. By outlining the resources needed - in both skill set and duration - it will cause the requesting party to think critically about the commitment needed to complete their project and what gap must be closed with regard to education of those resources. How - In the simple request form outlined above, resources and a commitment to fulfilling any needed education should be included with a brief acceptance clause that outlines the requesting party's commitment. Impact - This stage acts as a formal commitment to ensuring that resources are able to execute on the vision for the project. 4. Success Criteria Why - Similar to the business purpose, this is a key element in helping to determine if the project and its respective content should continue to exist if it does not meet its intended goal. How - Set a review point for the project content that will check the progress against the originally outlined success criteria and then determine the fate of the content. This can even include logic that will tell the content system to remove items that have not been opened by any users in X amount of time. Impact - This ensures that projects and their contents do not live past their useful lifespans. Just as with orphaned content, non-relevant information will slow user's access to relevant materials for the jobs. Request Phase Summary With a simple form that outlines the ownership of a project and its content, business purpose, education and resources, along with success criteria, we can ensure that an enterprise content management system will stay clean and relevant to end users - allowing it to deliver the most value possible. The key here is to make it straightforward to make the request and let the content management technology manage as much as possible through metadata, retention policies and workflow. Doing these basic steps will allow project content to get off to a great start in the enterprise! Stay tuned for the next installment - the "Create Phase" - covering security access and workflow involved in content creation, enabling a practical layer of governance over our enterprise content repository.

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• Can someone explain the true landscape of Rails vs PHP deployment, particularly within the context of Reseller-based web hosting (e.g., Hostgator)?

  - by rcd

  Currently, I have a reseller account with the company HostGator. I design websites, which up until now have occasionally been wrapped in Wordpress CMSs and the like (PHP applications). I then sell hosting (of the site I've designed) to the client, which is pretty simple, in that I can simply click a button and add a new shared hosting account/site with whatever settings I want. Furthermore, I then utilize WHMCS to automate billing and account management. It's a nice package and pretty simple. I pay something like $25 a month, and can sell a hundred accounts under this (because my clients bandwidth requirements are low). Now I am finding the need to develop more customized applications, including a minimalist CMS and several proprietary things. I soon anticipate developing these apps for clients as well. Thus, I've spent the past few months learning Rails, and it's coming along well now. The thing that has nagged at me all along, though, is the deployment issue. I can't wrap my brain around it. It seems like all of the popular options (Heroku, etc) have nice automation with git and are set up in the "Rails Way". I get that (sort of). But it's terribly expensive... a single dyno, a helper, and the cheapest database (which they say is mainly suitable for testing) that isn't limited to 5MB runs $51. This is for ONE app!!! Throw in a "production" DB and you're over $200. This is like... the same prices as getting a server somewhere, right? Meanwhile, going back to what I guess is a "traditional" hosting environment with Hostgator, their server only has Ruby 1.8.7 and Rails 2.3.5... No Rails 3. AND, no Passenger (not that I really understand the difference in CGI or mod_rails or whatever, but they say Passenger is the simplest). So I'm to understand that if I build an app in Rails 3, it won't run at all on this host? But damn, I already have these accounts under my reseller account there, all running static html and/or PHP stuff, right? So what now? How do I get all of this under one simple (and affordable) roof? Forgive my ignorance, but I just don't get it. Managing a VPS is cool and all, but entails learning server admin stuff and security... And it's expensive. I get that a shared and/or reseller "server-based" (forgive the terminology) may be inadequate for large-scale apps that use a lot of bandwidth... But what about for those of us who are building real (but small and low bandwidth) apps (with Rails) and who want to deploy them simply, cheaply, using the same conceptual approach as PHP? Even after learning all of this Ruby and Rails stuff for months, I'm questioning whether it's worth it when it comes to deployment. I want to build a small app, upload it to my home directory on a shared server account, and just make it run. Why should that be so hard? Am I just choosing the wrong language/framework? Forgive my ignorance in the subject; these questions are not rhetorical; just trying to learn here. So: 1) I'd appreciate if someone could give me a good rundown of how to understand deployment in Rails vs. PHP. 2) I'd appreciate if someone could address my issue with running a hosting/web business around reseller hosting (Hostgator) while also being able to host Rails apps. Can it be done? And how can a company like Hostgator completely ignore what's current in Rails/Ruby? Thanks.

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• Is the Leptonica implementation of 'Modified Median Cut' not using the median at all?

  - by TheCodeJunkie

  I'm playing around a bit with image processing and decided to read up on how color quantization worked and after a bit of reading I found the Modified Median Cut Quantization algorithm. I've been reading the code of the C implementation in Leptonica library and came across something I thought was a bit odd. Now I want to stress that I am far from an expert in this area, not am I a math-head, so I am predicting that this all comes down to me not understanding all of it and not that the implementation of the algorithm is wrong at all. The algorithm states that the vbox should be split along the lagest axis and that it should be split using the following logic The largest axis is divided by locating the bin with the median pixel (by population), selecting the longer side, and dividing in the center of that side. We could have simply put the bin with the median pixel in the shorter side, but in the early stages of subdivision, this tends to put low density clusters (that are not considered in the subdivision) in the same vbox as part of a high density cluster that will outvote it in median vbox color, even with future median-based subdivisions. The algorithm used here is particularly important in early subdivisions, and 3is useful for giving visible but low population color clusters their own vbox. This has little effect on the subdivision of high density clusters, which ultimately will have roughly equal population in their vboxes. For the sake of the argument, let's assume that we have a vbox that we are in the process of splitting and that the red axis is the largest. In the Leptonica algorithm, on line 01297, the code appears to do the following Iterate over all the possible green and blue variations of the red color For each iteration it adds to the total number of pixels (population) it's found along the red axis For each red color it sum up the population of the current red and the previous ones, thus storing an accumulated value, for each red note: when I say 'red' I mean each point along the axis that is covered by the iteration, the actual color may not be red but contains a certain amount of red So for the sake of illustration, assume we have 9 "bins" along the red axis and that they have the following populations 4 8 20 16 1 9 12 8 8 After the iteration of all red bins, the partialsum array will contain the following count for the bins mentioned above 4 12 32 48 49 58 70 78 86 And total would have a value of 86 Once that's done it's time to perform the actual median cut and for the red axis this is performed on line 01346 It iterates over bins and check they accumulated sum. And here's the part that throws me of from the description of the algorithm. It looks for the first bin that has a value that is greater than total/2 Wouldn't total/2 mean that it is looking for a bin that has a value that is greater than the average value and not the median ? The median for the above bins would be 49 The use of 43 or 49 could potentially have a huge impact on how the boxes are split, even though the algorithm then proceeds by moving to the center of the larger side of where the matched value was.. Another thing that puzzles me a bit is that the paper specified that the bin with the median value should be located, but does not mention how to proceed if there are an even number of bins.. the median would be the result of (a+b)/2 and it's not guaranteed that any of the bins contains that population count. So this is what makes me thing that there are some approximations going on that are negligible because of how the split actually takes part at the center of the larger side of the selected bin. Sorry if it got a bit long winded, but I wanted to be as thoroughas I could because it's been driving me nuts for a couple of days now ;)

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• jQuery validation plugin and .ajax

  - by FALCONSEYE

  So, I have a form where I load divs as I go asking for various user input and displaying some offers. I have the following: $("#calcPrice").click(function() { $("#invPricing").validate({ rules: { ... }, messages: {... } , submitHandler: function(form) { .... $.ajax({ }); $.ajax({ }); return false; } }); My problem is after validation, none of the ajax calls work. If I remove the validation methods (rules, messages, submitHandler), everything works fine. Can somebody tell me what I am missing here? thanks in advance. btw, these are the ajax calls: $.ajax({ dataType: "json", type: "get", url: <cfoutput>"#actURL#"</cfoutput>, data: formData+"&p_type=LOW&returnJSON=true", cache: false, success: function(result) { // fields to populate: $("#rent").val(result.RENT); $("#discount").val(result.DISCOUNT); $("#salesPrice1").val(result.SALESPRICE); $("#cashPrice1").val(result.CASHSALESPRICE); $("#tax1").val(result.SALESTAX); $("#payment1").val(result.PAYMENTS); } , error: function(xmlHttpRequest, status, err) { confirm('Error!' + err); } }); $.ajax({ dataType: "json", type: "get", url: <cfoutput>"#actURL#"</cfoutput>, data: formData+"&p_type=HIGH&returnJSON=true", cache: false, success: function(result) { // fields to populate: $("#rent").val(result.RENT); $("#discount").val(result.DISCOUNT); $("#salesPrice2").val(result.SALESPRICE); $("#cashPrice2").val(result.CASHSALESPRICE); $("#tax2").val(result.SALESTAX); $("#payment2").val(result.PAYMENTS); } , error: function(xmlHttpRequest, status, err) { confirm('Error!' + err); } }); I am basically displaying two offers one Low, one High.

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• WinForms DataGridView - update database

  - by Geo Ego

  I know this is a basic function of the DataGridView, but for some reason, I just can't get it to work. I just want the DataGridView on my Windows form to submit any changes made to it to the database when the user clicks the "Save" button. I populate the DataGridView according to a function triggered by a user selection in a DropDownList as follows: using (SqlConnection con = new SqlConnection(conString)) { con.Open(); SqlDataAdapter ruleTableDA = new SqlDataAdapter("SELECT rule.fldFluteType AS [Flute], rule.fldKnife AS [Knife], rule.fldScore AS [Score], rule.fldLowKnife AS [Low Knife], rule.fldMatrixScore AS [Matrix Score], rule.fldMatrix AS [Matrix] FROM dbo.tblRuleTypes rule WHERE rule.fldMachine_ID = '1003'", con); DataSet ruleTableDS = new DataSet(); ruleTableDA.Fill(ruleTableDS); RuleTable.DataSource = ruleTableDS.Tables[0]; } In my save function, I basically have the following (I've trimmed out some of the code around it to get to the point): using (SqlDataAdapter ruleTableDA = new SqlDataAdapter("SELECT rule.fldFluteType AS [Flute], rule.fldKnife AS [Knife], rule.fldScore AS [Score], rule.fldLowKnife AS [Low Knife], rule.fldMatrixScore AS [Matrix Score], rule.fldMatrix AS [Matrix] FROM dbo.tblRuleTypes rule WHERE rule.fldMachine_ID = '1003'", con)) { SqlCommandBuilder commandBuilder = new SqlCommandBuilder(ruleTableDA); DataTable dt = new DataTable(); dt = RuleTable.DataSource as DataTable; ruleTableDA.Fill(dt); ruleTableDA.Update(dt); } Okay, so I edited the code to do the following: build the commands, create a DataTable based on the DataGridView (RuleTable), fill the DataAdapter with the DataTable, and update the database. Now ruleTableDA.Update(dt) is throwing the exception "Concurrency violation: the UpdateCommand affected 0 of the expected 1 records."

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• process csv in scala

  - by portoalet

  I am using scala 2.7.7, and wanted to parse CSV file and store the data in SQLite database. I ended up using OpenCSV java library to parse the CSV file, and using sqlitejdbc library. Using these java libraries makes my scala code looks almost identical to that of Java code (sans semicolon and with val/var) As I am dealing with java objects, I can't use scala list, map, etc, unless I do scala2java conversion or upgrade to scala 2.8 Is there a way I can simplify my code further using scala bits that I don't know? val filename = "file.csv"; val reader = new CSVReader(new FileReader(filename)) var aLine = new Array[String](10) var lastSymbol = "" while( (aLine = reader.readNext()) != null ) { if( aLine != null ) { val symbol = aLine(0) if( !symbol.equals(lastSymbol)) { try { val rs = stat.executeQuery("select name from sqlite_master where name='" + symbol + "';" ) if( !rs.next() ) { stat.executeUpdate("drop table if exists '" + symbol + "';") stat.executeUpdate("create table '" + symbol + "' (symbol,data,open,high,low,close,vol);") } } catch { case sqle : java.sql.SQLException => println(sqle) } lastSymbol = symbol } val prep = conn.prepareStatement("insert into '" + symbol + "' values (?,?,?,?,?,?,?);") prep.setString(1, aLine(0)) //symbol prep.setString(2, aLine(1)) //date prep.setString(3, aLine(2)) //open prep.setString(4, aLine(3)) //high prep.setString(5, aLine(4)) //low prep.setString(6, aLine(5)) //close prep.setString(7, aLine(6)) //vol prep.addBatch() prep.executeBatch() } } conn.close()

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• Best method of achieving bi-directional communication between Apple iPad "clients" and a Windows Ser

  - by user361910

  We are currently starting to build a client-server system which will see 10 or more Apple iPad client devices communicating to a central Windows server over a wireless LAN. We wanted to some existing plumbing (.NET remoting/WCF/web services/etc) that would allow us to implement a reliable, secure solution without having to start at a low level (e.g. sockets) and recreate the wheel. One of the major requirements that complicates this scenario is that unlike a traditional web service, the windows server needs to be able to arbitrarily notify the clients whenever certain events occur -- so it is not a simple request/response scenario like the web. Initially, we were going to use Windows clients, so our plan was to use the full-duplex mode of .NET WCF over HTTP|TCP. But now using the iPad, we don't have any of the WCF infrastructure. So my question is: what is the best way to allow an iPad and a Windows server to (securely) communicate over a LAN, with each device able to initiate communication to the other? Am I stuck writing low-level socket code? Thanks!

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• ASP.NET Membership

  - by Gary McGill

  I'd like to use the ASP.NET membership provider in the following (low-security) scenario... My company will create and administer user accounts on behalf of our clients. These accounts will likely be shared amongst several people in the client company (is that a problem?). There will be 2 types of users (2 roles): client and administrator. Administrators are the people within my company that will have special privileges to create client user accounts, etc. Clients will not be able to self-register. They also won't get to choose their own password, and they should not be able to change their password either, since that will just create confusion where several people are sharing the same account. My internal users (admins) will set the password for each client. Here's the bit I'm struggling with: if a client phones up and asks to be reminded of their password, how can my admin users find out what the password is? Can I configure the provider to store the password in clear text (or other recoverable form), and if so can I get at the password through the .NET API? As I said at the outset, this is a low-security application, and so I plan simply to show the password in the (internal) web page where I have a list of all users.

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• Zend php memory memory_limit

  - by RepDetec

  All, I am working on a Zend Framework based web application. We keep encountering out of memory errors on our dev server: Allowed memory size of XXXX bytes exhausted (tried YYYY... We keep increasing memory_limit in php.ini, but it is now up over 1000 megs. What is a normal memory_limit value? What are the usual suspects in php/Zend for running out of memory? We are using the Propel ORM. Thanks for all of the help! Update I cannot reproduce this error in my windows environment. If I set memory_limit low (say 16M), I get the same error, but the "tried to allocate" amount is always something reasonable. For example: (tried to allocate 13344 bytes) If I set the memory very low on the (Fedora 9) server (such as 16M), I get the same thing. consistent, reasonable out of memory errors. However, even when the memory limit is set very high on our server (128M, for example), maybe once a week, I will get an crazy huge memory error: (tried to allocate 1846026201 bytes). I don't know if that might shed any more light onto what is going on. We are using propel 1.5. It sounds like the actual release is going to come out later this month, but it doesn't look like anyone else is having this problem with it anyway. I don't know that Propel is the problem. We are using Zend Server with php 5.2 on the Linux box, and 5.3 locally. Any more ideas? I have a ticket out to get Xdebug installed on the Linux box. Thanks, -rep

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• rails + sheevaplug = rails home development server and more

  - by microspino

  Hello I'd like to build a "Rails Brick" using a Sheevaplug from Marvell (O.S. is Ubuntu out of the box but You can install other distributions on It). It will be a home server and a silent, low cost (99$) low energy development machine. I'd like to add rails RVM, lot of gems, git-based heroku like deployment, passenger + nginx. This way I could have a portable server with a complete development environment and maybe I could find a hosting company where I can co-locate a grid of this devices or I can sell It as a simple little server for 10 or less users offices, with some centralized rails services (I think to a CMS, a BLOG, a WIKI, calendar or whatever this little jewel could afford). The usb port could make It a print server too or a UMTS link to the web via HUAWEI like usb UMTS keys. Can you give me some hint about: Is this project a crazy-close-to-failure idea? Why? which gem would You include? which rails open source app would you suggest? I have already an Excito Bubba Server at home, I saw the TonidoPlug so It came up in my mind to build something similiar but Rails based (Bubba is PHP based, TonidoPlug I don't know but It does not seems a Rails thing).

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• Isolated storage misunderstand

  - by Costa

  Hi this is a discussion between me and me to understand isolated storage issue. can you help me to convince me about isolated storage!! This is a code written in windows form app (reader) that read the isolated storage of another win form app (writer) which is signed. where is the security if the reader can read the writer's file, I thought only signed code can access the file! If all .Net applications born equal and have all permissions to access Isolated storage, where is the security then? If I can install and run Exe from isolated storage, why I don't install a virus and run it, I am trusted to access this area. but the virus or what ever will not be trusted to access the rest of file system, it only can access the memory, and this is dangerous enough. I cannot see any difference between using app data folder to save the state and using isolated storage except a long nasty path!! I want to try give low trust to Reader code and retest, but they said "Isolated storage is actually created for giving low trusted application the right to save its state". Reader code: private void button1_Click(object sender, EventArgs e) { String path = @"C:\Documents and Settings\All Users\Application Data\IsolatedStorage\efv5cmbz.ewt\2ehuny0c.qvv\StrongName.5v3airc2lkv0onfrhsm2h3uiio35oarw\AssemFiles\toto12\ABC.txt"; StreamReader reader = new StreamReader(path); var test = reader.ReadLine(); reader.Close(); } Writer: private void button1_Click(object sender, EventArgs e) { IsolatedStorageFile isolatedFile = IsolatedStorageFile.GetMachineStoreForAssembly(); isolatedFile.CreateDirectory("toto12"); IsolatedStorageFileStream isolatedStorage = new IsolatedStorageFileStream(@"toto12\ABC.txt", System.IO.FileMode.Create, isolatedFile); StreamWriter writer = new StreamWriter(isolatedStorage); writer.WriteLine("Ana 2akol we ashrab kai a3eesh wa akbora"); writer.Close(); writer.Dispose(); }

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• Beginner python - stuck in a loop

  - by Jeremy

  I have two begininer programs, both using the 'while' function, one works correctly, and the other gets me stuck in a loop. The first program is this; num=54 bob = True print('The guess a number Game!') while bob == True: guess = int(input('What is your guess? ')) if guess==num: print('wow! You\'re awesome!') print('but don\'t worry, you still suck') bob = False elif guess>num: print('try a lower number') else: print('close, but too low') print('game over')`` and it gives the predictable output of; The guess a number Game! What is your guess? 12 close, but too low What is your guess? 56 try a lower number What is your guess? 54 wow! You're awesome! but don't worry, you still suck game over However, I also have this program, which doesn't work; #define vars a = int(input('Please insert a number: ')) b = int(input('Please insert a second number: ')) #try a function def func_tim(a,b): bob = True while bob == True: if a == b: print('nice and equal') bob = False elif b > a: print('b is picking on a!') else: print('a is picking on b!') #call a function func_tim(a,b) Which outputs; Please insert a number: 12 Please insert a second number: 14 b is picking on a! b is picking on a! b is picking on a! ...(repeat in a loop).... Can someone please let me know why these programs are different? Thank you!

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• SQL Server Clustered Index: (Physical) Data Page Order

  - by scherand

  I am struggling understanding what a clustered index in SQL Server 2005 is. I read the MSDN article Clustered Index Structures (among other things) but I am still unsure if I understand it correctly. The (main) question is: what happens if I insert a row (with a "low" key) into a table with a clustered index? The above mentioned MSDN article states: The pages in the data chain and the rows in them are ordered on the value of the clustered index key. And Using Clustered Indexes for example states: For example, if a record is added to the table that is close to the beginning of the sequentially ordered list, any records in the table after that record will need to shift to allow the record to be inserted. Does this mean that if I insert a row with a very "low" key into a table that already contains a gazillion rows literally all rows are physically shifted on disk? I cannot believe that. This would take ages, no? Or is it rather (as I suspect) that there are two scenarios depending on how "full" the first data page is. A) If the page has enough free space to accommodate the record it is placed into the existing data page and data might be (physically) reordered within that page. B) If the page does not have enough free space for the record a new data page would be created (anywhere on the disk!) and "linked" to the front of the leaf level of the B-Tree? This would then mean the "physical order" of the data is restricted to the "page level" (i.e. within a data page) but not to the pages residing on consecutive blocks on the physical hard drive. The data pages are then just linked together in the correct order. Or formulated in an alternative way: if SQL Server needs to read the first N rows of a table that has a clustered index it can read data pages sequentially (following the links) but these pages are not (necessarily) block wise in sequence on disk (so the disk head has to move "randomly"). How close am I? :)

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• ActiveX not working properly with default security settings

  - by Ummar

  I have written an ActiveX control in C# and have made it working using regasm command, and it works fine as long as the security level is set to low.. Then as a next step I have made a .cab installer (ICD - Internet component downloader), and have signed my .cab file and ActiveX .dll file with a test certificate. when I hit the html page from my browser the installation parts works fine with default security settings of IE, but at the end it seems that nothing is installed and a red cross is shown on place of ActiveX. Moreover I have explored the Download Program Files folder under Windows directory, in status column it is showing word "unknown". while it is "installed" for all other activeX. what may be the problem. Moreover if i use the regasm command to register the assembly it works fine, and I have signed the ActiveX but still I have to move the security bar to low in my browser setting? why it is so? then what is the purpose of signing? I have used RegisterServer=yes in my .inf file Please let me know, if some one has gone through this problem already?

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• Does query plan optimizer works well with joined/filtered table-valued functions?

  - by smoothdeveloper

  In SQLSERVER 2005, I'm using table-valued function as a convenient way to perform arbitrary aggregation on subset data from large table (passing date range or such parameters). I'm using theses inside larger queries as joined computations and I'm wondering if the query plan optimizer work well with them in every condition or if I'm better to unnest such computation in my larger queries. Does query plan optimizer unnest table-valued functions if it make sense? If it doesn't, what do you recommend to avoid code duplication that would occur by manually unnesting them? If it does, how do you identify that from the execution plan? code sample: create table dbo.customers ( [key] uniqueidentifier , constraint pk_dbo_customers primary key ([key]) ) go /* assume large amount of data */ create table dbo.point_of_sales ( [key] uniqueidentifier , customer_key uniqueidentifier , constraint pk_dbo_point_of_sales primary key ([key]) ) go create table dbo.product_ranges ( [key] uniqueidentifier , constraint pk_dbo_product_ranges primary key ([key]) ) go create table dbo.products ( [key] uniqueidentifier , product_range_key uniqueidentifier , release_date datetime , constraint pk_dbo_products primary key ([key]) , constraint fk_dbo_products_product_range_key foreign key (product_range_key) references dbo.product_ranges ([key]) ) go . /* assume large amount of data */ create table dbo.sales_history ( [key] uniqueidentifier , product_key uniqueidentifier , point_of_sale_key uniqueidentifier , accounting_date datetime , amount money , quantity int , constraint pk_dbo_sales_history primary key ([key]) , constraint fk_dbo_sales_history_product_key foreign key (product_key) references dbo.products ([key]) , constraint fk_dbo_sales_history_point_of_sale_key foreign key (point_of_sale_key) references dbo.point_of_sales ([key]) ) go create function dbo.f_sales_history_..snip.._date_range ( @accountingdatelowerbound datetime, @accountingdateupperbound datetime ) returns table as return ( select pos.customer_key , sh.product_key , sum(sh.amount) amount , sum(sh.quantity) quantity from dbo.point_of_sales pos inner join dbo.sales_history sh on sh.point_of_sale_key = pos.[key] where sh.accounting_date between @accountingdatelowerbound and @accountingdateupperbound group by pos.customer_key , sh.product_key ) go -- TODO: insert some data -- this is a table containing a selection of product ranges declare @selectedproductranges table([key] uniqueidentifier) -- this is a table containing a selection of customers declare @selectedcustomers table([key] uniqueidentifier) declare @low datetime , @up datetime -- TODO: set top query parameters . select saleshistory.customer_key , saleshistory.product_key , saleshistory.amount , saleshistory.quantity from dbo.products p inner join @selectedproductranges productrangeselection on p.product_range_key = productrangeselection.[key] inner join @selectedcustomers customerselection on 1 = 1 inner join dbo.f_sales_history_..snip.._date_range(@low, @up) saleshistory on saleshistory.product_key = p.[key] and saleshistory.customer_key = customerselection.[key] I hope the sample makes sense. Much thanks for your help!

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• Delphi 6 OleServer.pas Invoke memory leak

  - by Mike Davis

  There's a bug in delphi 6 which you can find some reference online for when you import a tlb the order of the parameters in an event invocation is reversed. It is reversed once in the imported header and once in TServerEventDIspatch.Invoke. you can find more information about it here: http://cc.embarcadero.com/Item/16496 somewhat related to this issue there appears to be a memory leak in TServerEventDispatch.Invoke with a parameter of a Variant of type Var_Array (maybe others, but this is the more obvious one i could see). The invoke code copies the args into a VarArray to be passed to the event handler and then copies the VarArray back to the args after the call, relevant code pasted below: // Set our array to appropriate length SetLength(VarArray, ParamCount); // Copy over data for I := Low(VarArray) to High(VarArray) do VarArray[I] := OleVariant(TDispParams(Params).rgvarg^[I]); // Invoke Server proxy class if FServer <> nil then FServer.InvokeEvent(DispID, VarArray); // Copy data back for I := Low(VarArray) to High(VarArray) do OleVariant(TDispParams(Params).rgvarg^[I]) := VarArray[I]; // Clean array SetLength(VarArray, 0); There are some obvious work-arounds in my case: if i skip the copying back in case of a VarArray parameter it fixes the leak. to not change the functionality i thought i should copy the data in the array instead of the variant back to the params but that can get complicated since it can hold other variants and seems to me that would need to be done recursively. Since a change in OleServer will have a ripple effect i want to make sure my change here is strictly correct. can anyone shed some light on exactly why memory is being leaked here? I can't seem to look up the callstack any lower than TServerEventDIspatch.Invoke (why is that?) I imagine that in the process of copying the Variant holding the VarArray back to the param list it added a reference to the array thus not allowing it to be release as normal but that's just a rough guess and i can't track down the code to back it up. Maybe someone with a better understanding of all this could shed some light?

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• Why are my CATransitions acting up?

  - by Regan

  I am using the following code to switch between views with CATransition. CATransition *applicationLoadViewIn = [CATransition animation]; [applicationLoadViewIn setDuration:20]; [applicationLoadViewIn setType:kCATransitionPush]; [applicationLoadViewIn setSubtype:kCATransitionFromTop]; [applicationLoadViewIn setTimingFunction:[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseIn]]; ViewToSwitchTo *myviewcontroller = [[ViewToSwitchTo alloc] init]; [self.view.layer addAnimation:applicationLoadViewIn forKey:kCATransitionPush]; [self.view addSubview:myviewcontroller.view]; It functions mostly how I want it to. It pushes from the top like it should, however it for some reason acts strangely. First, the view I am switching to starts coming in from the bottom like it should, but for some reason, the view that I am switching FROM appears over the top of it with low opacity, so you see both of them. However, you also see the view that is coming in, shifted maybe 100 pixels upwards, on top of itself and the other view, once again with low opacity. Just before the halfway point of the the transition, everything works fine, you only see the view that is coming in and the view going out, doing what they should be doing. But slightly after the halfway point, the view I am switching to appears in its final destination, under the view I am switching from, and the view I am switching from has been reduced in opacity. What is going on here?

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• Haskell math performance

  - by Travis Brown

  I'm in the middle of porting David Blei's original C implementation of Latent Dirichlet Allocation to Haskell, and I'm trying to decide whether to leave some of the low-level stuff in C. The following function is one example—it's an approximation of the second derivative of lgamma: double trigamma(double x) { double p; int i; x=x+6; p=1/(x*x); p=(((((0.075757575757576*p-0.033333333333333)*p+0.0238095238095238) *p-0.033333333333333)*p+0.166666666666667)*p+1)/x+0.5*p; for (i=0; i<6 ;i++) { x=x-1; p=1/(x*x)+p; } return(p); } I've translated this into more or less idiomatic Haskell as follows: trigamma :: Double -> Double trigamma x = snd $ last $ take 7 $ iterate next (x' - 1, p') where x' = x + 6 p = 1 / x' ^ 2 p' = p / 2 + c / x' c = foldr1 (\a b -> (a + b * p)) [1, 1/6, -1/30, 1/42, -1/30, 5/66] next (x, p) = (x - 1, 1 / x ^ 2 + p) The problem is that when I run both through Criterion, my Haskell version is six or seven times slower (I'm compiling with -O2 on GHC 6.12.1). Some similar functions are even worse. I know practically nothing about Haskell performance, and I'm not terribly interested in digging through Core or anything like that, since I can always just call the handful of math-intensive C functions through FFI. But I'm curious about whether there's low-hanging fruit that I'm missing—some kind of extension or library or annotation that I could use to speed up this numeric stuff without making it too ugly.

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