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  • What's the most efficient way to find barycentric coordinates?

    - by bobobobo
    In my profiler, finding barycentric coordinates is apparently somewhat of a bottleneck. I am looking to make it more efficient. It follows the method in shirley, where you compute the area of the triangles formed by embedding the point P inside the triangle. Code: Vector Triangle::getBarycentricCoordinatesAt( const Vector & P ) const { Vector bary ; // The area of a triangle is real areaABC = DOT( normal, CROSS( (b - a), (c - a) ) ) ; real areaPBC = DOT( normal, CROSS( (b - P), (c - P) ) ) ; real areaPCA = DOT( normal, CROSS( (c - P), (a - P) ) ) ; bary.x = areaPBC / areaABC ; // alpha bary.y = areaPCA / areaABC ; // beta bary.z = 1.0f - bary.x - bary.y ; // gamma return bary ; } This method works, but I'm looking for a more efficient one!

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  • tomcat6 manager

    - by Bary W Pollack
    I've just installed Ubuntu 10.04 LTS Server with LAMP support. Tomcat6 seems to run ok. But, I am unable to get into the manager-webapp... I've updated the tomcat-users.xml file: <?xml version='1.0' encoding='utf-8'?> <tomcat-users> <role rolename="tomcat"/> <role rolename="role1"/> <role rolename="manager"/> <role rolename="admin"/> <user username="tomcat" password="tomcat" roles="tomcat,manager,admin"/> <user username="both" password="tomcat" roles="tomcat,role1"/> <user username="role1" password="tomcat" roles="role1"/> <user username="admin" password="admin" roles="manager,admin"/> </tomcat-users> But, no matter what I try, it keeps rejecting my username/password combo. What might I be missing?

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  • What's the normal way machine-learning algorithms are integrated into normal programs?

    - by Benjamin Pollack
    I'm currently taking a machine learning course for fun, and the course heavily focuses on Matlab/Octave to write the code. One thing mentioned in the course is that, while Matlab/Octave are great for prototyping, they're very rarely used for production algorithms. Instead, those algorithms are typically rewritten in C++/Python/etc., using appropriate libraries, before reaching customers. Fair enough; I get that. But here's my question: is that done for cultural reasons, for technical reasons, or because there is really no language that provides Matlab/Octave-like fluidity, but in a compiled form that can be linked from C/C++/$MainstreamLanguage? The game industry uses Lua for game logic because it's easy to embed, and vastly superior for expressing things like AI. Likewise, there are Prolog variants for rules-heavy applications, Scheme variants for compilers, and so on. If there's a matrix equivalent language, what is it? If there isn't, why is this field different?

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  • How do large blobs affect SQL delete performance, and how can I mitigate the impact?

    - by Max Pollack
    I'm currently experiencing a strange issue that my understanding of SQL Server doesn't quite mesh with. We use SQL as our file storage for our internal storage service, and our database has about half a million rows in it. Most of the files (86%) are 1mb or under, but even on fresh copies of our database where we simply populate the table with data for the purposes of a test, it appears that rows with large amounts of data stored in a BLOB frequently cause timeouts when our SQL Server is under load. My understanding of how SQL Server deletes rows is that it's a garbage collection process, i.e. the row is marked as a ghost and the row is later deleted by the ghost cleanup process after the changes are copied to the transaction log. This suggests to me that regardless of the size of the data in the blob, row deletion should be close to instantaneous. However when deleting these rows we are definitely experiencing large numbers of timeouts and astoundingly low performance. In our test data set, its files over 30mb that cause this issue. This is an edge case, we don't frequently encounter these, and even though we're looking into SQL filestream as a solution to some of our problems, we're trying to narrow down where these issues are originating from. We ARE performing our deletes inside of a transaction. We're also performing updates to metadata such as file size stats, but these exist in a separate table away from the file data itself. Hierarchy data is stored in the table that contains the file information. Really, in the end it's not so much what we're doing around the deletes that matters, we just can't find any references to low delete performance on rows that contain a large amount of data in a BLOB. We are trying to determine if this is even an avenue worth exploring, or if it has to be one of our processes around the delete that's causing the issue. Are there any situations in which this could occur? Is it common for a database server to come to the point of complete timeouts when many of these deletes are occurring simultaneously? Is there a way to combat this issue if it exists? (cross-posted from StackOverflow )

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  • Under what circumstances would a junction point be more appropriate than a symbolic link?

    - by Benjamin Pollack
    Symbolic links were introduced an incredibly long time ago in Windows, yet I still encounter a large number of systems that use junction points. I know that symbolic links afford functionality not in junction points (e.g., they work on external drives); my question is whether there is functionality specific to junction points that make them more appropriate than symbolic links in some circumstances.

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  • Unit Test For NpgsqlCommand With Rhino Mocks

    - by J Pollack
    My unit test keeps getting the following error: "System.InvalidOperationException: The Connection is not open." The Test [TestFixture] public class Test { [Test] public void Test1() { NpgsqlConnection connection = MockRepository.GenerateStub<NpgsqlConnection>(); // Tried to fake the open connection connection.Stub(x => x.State).Return(ConnectionState.Open); connection.Stub(x => x.FullState).Return(ConnectionState.Open); DbQueries queries = new DbQueries(connection); bool procedure = queries.ExecutePreProcedure("201003"); Assert.IsTrue(procedure); } } Code Under Test using System.Data; using Npgsql; public class DbQueries { private readonly NpgsqlConnection _connection; public DbQueries(NpgsqlConnection connection) { _connection = connection; } public bool ExecutePreProcedure(string date) { var command = new NpgsqlCommand("name_of_procedure", _connection); command.CommandType = CommandType.StoredProcedure; NpgsqlParameter parameter = new NpgsqlParameter {DbType = DbType.String, Value = date}; command.Parameters.Add(parameter); command.ExecuteScalar(); return true; } } How would you test the code using Rhino Mocks 3.6? PS. NpgsqlConnection is a connection to a PostgreSQL server.

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  • Where can I get resources for developing for Mac OS Classic?

    - by Benjamin Pollack
    I recently got bored and fired up my old Mac OS Classic emulator, and then got nostalgic for writing old-school applications for the system. So, my question: Where can I get dev tools that can still target Classic? (Ideally free, since this is just for fun, but if grabbing a used version of CodeWarrior on eBay is the best way to go, so be it.) Where can I get at least reference materials so I don't have to guess-and-check my way around Carbon/the System Toolbox? Are there any forums still running that would be open to answering old-school Mac questions for when I get stuck? This is purely for fun, so don't worry about how impractical this is. I know.

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  • Which full-text search package should I use for SQLite3?

    - by Benjamin Pollack
    SQLite3 appears to come with three different full-text search engines, called FTS1, FTS2, and FTS3. The documentation available on the website mentions that FTS1 is stable, FTS2 is in development, and that you should use FTS2. Examples I find online use FTS3, which is in CVS, and not documented versus FTS2. None of the full-text search engines come with the amalgamated source, as near as I can tell. So, my question: which of these three engines, if any, should I use for full-text indexing in SQLite? Or should I simply use a third-party tool like Sphinx, or a custom solution in Lucene, instead?

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  • Integer comparison as string

    - by J Pollack
    Hi I have an integer column and I want to find numbers that start with specific digits. For example they do match if I look for '123': 1234567 123456 1234 They do not match: 23456 112345 0123445 Is the only way to handle the task by converting the Integers into Strings before doing string comparison? Also I am using Postgre regexp_replace(text, pattern, replacement) on numbers which is very slow and inefficient way doing it. The case is that I have large amount of data to handle this way and I am looking for the most economical way doing this.

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  • how can i pass 2 arrays as datas in googlechart

    - by gin
    I'm using google charts easy php class (here's the link of it) and i want to draw Multiple Vertical Bar Chart, as the documentation says "Separate multiple data sets with |" so i try this , but nothing happens $chart1=new googleChart($a | $b ,'bary' ); *note that both $a & $b are arrays i would appreciate any help :)

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  • SOA Implementation Challenges

    Why do companies think that if they put up a web service that they are doing Service-Oriented Architecture (SOA)? Unfortunately, the IT and business world love to run on the latest hype or buzz words of which very few even understand the meaning. One of the largest issues companies have today as they consider going down the path of SOA, is the lack of knowledge regarding the architectural style and the over usage of the term SOA. So how do we solve this issue?I am sure most of you are thinking by now that you know what SOA is because you developed a few web services.  Isn’t that SOA, right? No, that is not SOA, but instead Just Another Web Service (JAWS). For us to better understand what SOA is let’s look at a few definitions.Douglas K. Bary defines service-oriented architecture as a collection of services. These services are enabled to communicate with each other in order to pass data or coordinating some activity with other services.If you look at this definition closely you will notice that Bary states that services communicate with each other. Let us compare this statement with my first statement regarding companies that claim to be doing SOA when they have just a collection of web services. In order for these web services to for an SOA application they need to be interdependent on one another forming some sort of architectural hierarchy. Just because a company has a few web services does not mean that they are all interconnected.SearchSOA from TechTarget.com states that SOA defines how two computing entities work collectively to enable one entity to perform a unit of work on behalf of another. Once again, just because a company has a few web services does not guarantee that they are even working together let alone if they are performing work for each other.SearchSOA also points out service interactions should be self-contained and loosely-coupled so that all interactions operate independent of each other.Of all the definitions regarding SOA Thomas Erl’s seems to shed the most light on this concept. He states that “SOA establishes an architectural model that aims to enhance the efficiency, agility, and productivity of an enterprise by positioning services as the primary means through which solution logic is represented in support of the realization of the strategic goals associated with service-oriented computing.” (Erl, 2011) Once again this definition proves that a collection of web services does not mean that a company is doing SOA. However, it does mean that a company has a collection of web services, and that is it.In order for a company to start to go down the path of SOA, they must take  a hard look at their existing business process while abstracting away any technology so that they can define what is they really want to accomplish. Once a company has done this, they can begin to factor out common sub business process like credit card process, user authentication or system notifications in to small components that can be built independent of each other and then reassembled to form new and dynamic services that are loosely coupled and agile in that they can change as a business grows.Another key pitfall of companies doing SOA is the fact that they let vendors drive their architecture. Why do companies do this? Vendors’ do not hold your company’s success as their top priority; in fact they hold their own success as their top priority by selling you as much stuff as you are willing to buy. In my experience companies tend to strive for the maximum amount of benefits with a minimal amount of cost. Does anyone else see any conflicts between this and the driving force behind vendors.Mike Kavis recommends in an article written in CIO.com that companies need to figure out what they need before they talk to a vendor or at least have some idea of what they need. It is important to thoroughly evaluate each vendor and watch them perform a live demo of their system so that you as the company fully understand what kind of product or service the vendor is actually offering. In addition, do research on each vendor that you are considering, check out blog posts, online reviews, and any information you can find on the vendor through various search engines.Finally he recommends companies to verify any recommendations supplied by a vendor. From personal experience this is very important. I can remember when the company I worked for purchased a $200,000 add-on to their phone system that never actually worked as it was intended. In fact, just after my departure from the company started the process of attempting to get their money back from the vendor. This potentially could have been avoided if the company had done the research before selecting this vendor to ensure that their product and vendor would live up to their claims. I know that some SOA vendor offer free training regarding SOA because they know that there are a lot of misconceptions about the topic. Superficially this is a great thing for companies to take part in especially if the company is starting to implement SOA architecture and are still unsure about some topics or are looking for some guidance regarding the topic. However beware that some companies will focus on their product line only regarding the training. As an example, InfoWorld.com claims that companies providing deep seminars disguised as training, focusing more about ESBs and SOA governance technology, and less on how to approach and solve the architectural issues of the attendees.In short, it is important to remember that we as software professionals are responsible for guiding a business’s technology sections should be well informed and fully understand any new concepts that may be considered for implementation. As I have demonstrated already a company that has a few web services does not mean that they are doing SOA.  Additionally, we must not let the new buzz word of the day drive our technology, but instead our technology decisions should be driven from research and proven experience. Finally, it is important to rely on vendors when necessary, however, always take what they say with a grain of salt while cross checking any claims that they may make because we have to live with the aftermath of a system after the vendors are gone.   References: Barry, D. K. (2011). Service-oriented architecture (SOA) definition. Retrieved 12 12, 2011, from Service-Architecture.com: http://www.service-architecture.com/web-services/articles/service-oriented_architecture_soa_definition.html Connell, B. (2003, 9). service-oriented architecture (SOA). Retrieved 12 12, 2011, from SearchSOA: http://searchsoa.techtarget.com/definition/service-oriented-architecture Erl, T. (2011, 12 12). Service-Oriented Architecture. Retrieved 12 12, 2011, from WhatIsSOA: http://www.whatissoa.com/p10.php InfoWorld. (2008, 6 1). Should you get your SOA knowledge from SOA vendors? . Retrieved 12 12, 2011, from InfoWorld.com: http://www.infoworld.com/d/architecture/should-you-get-your-soa-knowledge-soa-vendors-453 Kavis, M. (2008, 6 18). Top 10 Reasons Why People are Making SOA Fail. Retrieved 12 13, 2011, from CIO.com: http://www.cio.com/article/438413/Top_10_Reasons_Why_People_are_Making_SOA_Fail?page=5&taxonomyId=3016  

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  • Get Smarter Just By Listening

    - by mark.wilcox
    Occasionally my friends ask me what do I listen/read to keep informed. So I thought I would like to post an update. First - there is an entirely new network being launched by Jason Calacanis called "ThisWeekIn". They have weekly shows on variety of topics including Startups, Android, Twitter, Cloud Computing, Venture Capital and now the iPad. If you want to keep ahead (and really get motivated) - I totally recommend listening to at least This Week in Startups. I also find Cloud Computing helpful. I also like listening to the Android show so that I can see how it's progressing. Because while I love my iPhone/iPad - it's  important to keep the competition in the game up to improve everything. I'm also not opposed to switching to Android if something becomes as nice experience - but so far - my take on Android devices are  - 10 years ago, I would have jumped all over them because of their hackability. But now, I'm in a phase, where I just want these devices to work and most of my creation is in non-programming areas - I find the i* experience better. Second - In terms of general entertaining tech news - I'm a big fan of This Week in Tech. Finally - For a non-geek but very informative show - The Kevin Pollack Show on ThisWeekIn network gets my highest rating. It's basically two-hours of in-depth interview with a wide variety of well-known comedian and movie stars. -- Posted via email from Virtual Identity Dialogue

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  • Spring.NET. How actively is it being developed/supported?

    - by Bubba88
    I've made my choice for the developement components on the .NET platform: Spring.NET for IoC and NHibernate for data access. But how safe is it? I've heard here on SO (don't remember which post exactly) that Spring.NET is on its way down, cause for example the Java original version is developed by a large number of people; but (they say that) the sole person behind the .NET version is Mr. Mark Pollack. Is that so? And, if so, does it still make sense to count on Spring.NET for my production applications? if you have similar information about NHibernate, I'll appreciate it; though it seems that the latter is actively supported.

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  • Confused about GNU `sort(1)` of a numerical sub field

    - by Chen Levy
    I wish to sort a space separated table, with the numerical value that found on the 2nd field. I can assume that the 2nd field is always fooN but the length of N is unknown: antiq. foo11 girls colleaguing foo2 Leinsdorf Cousy foo0 Montgomeryville bowlegged foo1 pollack Chevrier foo10 ill-conceived candlebomb foo3 seventieths autochthony foo101 re-enable beneficiate foo100 osteometric I read man sort(1) and played with all sort of options. On my system I found the line: sort -n -k2.5 table to work. My question is why? According to the man page: -k, --key=POS1[,POS2] start a key at POS1, end it at POS 2 (origin 1) ... POS is F[.C][OPTS], where F is the field number and C the characterposition in the field. OPTS is one or more single-letter ordering options, which override global ordering options for that key. If no key is given, use the entire line as the key. So why sort -n -k2.4 table don't work and sort -n -k.5 does?

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  • Why do people say that Ruby is slow?

    - by stephen murdoch
    I like Ruby on Rails and I use it for all my web development projects. A few years ago there was a lot of talk about Rails being a memory hog and about how it didn't scale very well but these suggestions were put to bed by Gregg Pollack here. Lately though, I've been hearing people saying that Ruby itself is slow. Why is Ruby considered slow? I do not find Ruby to be slow but then again, I'm just using it to make simple CRUD apps and company blogs. What sort of projects would I need to be doing before I find Ruby becoming slow? Or is this slowness just something that affects all programming languages? What are your options as a Ruby programmer if you want to deal with this "slowness"? Which version of Ruby would best suit an application like Stack Overflow where speed is critical and traffic is intense? The questions are subjective, and I realise that architectural setup (EC2 vs standalone servers etc) makes a big difference but I'd like to hear what people think about Ruby being slow. Finally, I can't find much news on Ruby 2.0 - I take it we're a good few years away from that then?

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