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  • How to introduce a computer illiterate 50-year old to programming [closed]

    - by sunday
    The other day my dad asked me a question that I would have never expected from him. "How can I learn C++?" My dad is turning 56 this year and computers are a distant concept for him. He doesn't know how to use a phone very well besides calling numbers (no speed dial or contacts); though he has started to learn computers a little better - to the point that he knows how to open the internet (in Windows) and browse around (and has successfully completed several job applications entirely on his own online, of which he was offered positions too). But still, these are too narrow-windowed experiences to mean much, really. While he may not have the background, my dad knows how to read. And I mean reading as a skill, not just an ability. He has little to no college education (financial problems, family, etc.) and was fortunate enough to finish high school, but still taught himself to become a master electrician and has been one for almost 30 years now. He did the same with guitar, learning to play at a very professional level and has been praised for his skill. In high school, he picked up a weight lifting book - and was the only person in his high school at the time to qualify officially as an "athlete" by national standards. In all cases, he just needed something to read. Something to teach him. He absorbs information like a sponge. I have no doubt in my dad's motivation or capability of doing this, so my general goal is simply: Get my dad into the world of computers, and get him on the road to programming. I strongly believe that once I get him through the fundamentals, his drive and reading skill will keep him going on this own. So I'm asking you all: where should I start with all this? And what are the best resources out there? Should I get him to start Linux instead of Windows? Is C++ a bad idea? Remember, he needs to (IMO) learn computers first, and then get that first grasp (the "Hello world" experience) of programming. For money's sake and at top preference, I'd like free online resources that he can read, but by all means any good suggestions in print or paid-for-online are welcome (that I could possibly look into later to purchase). And also, I intend to start him off with C++ (no Python, Java, etc.), because I know it the best and will be able to help him along the way with code. (I have minimal knowledge right now in other languages). Edit: I'm getting a lot of persistent suggestions to use Python. The only reason I wanted to do C++ is that I KNOW it and can be THERE when my dad needs help. My VERY FIRST exposure to programming ever was Java. I learned Java, and I got good at it. I open to other suggestions, but please provide an effective application of your suggestions. EDIT #2: I understand my approach/thinking/knowledge could be lacking here. I'm a sophomore level undergraduate CS major. If you don't agree with anything in my post, tell me why - give me ideas, information - that's why I'm asking in the first place. To narrow down my general goal to specific reachable goals.

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  • Making user input/math on data fast, unlike excel type programs

    - by proGrammar
    I'm creating a research platform solely for myself to do some research on data. Programs like excel are terribly slow for me so I'm trying to come up with another solution. Originally I used excel. A1 was the cell that contained the data and all other cells in use calculated something on A1, or on other cells, that all could be in the end traced to A1. A1 was like an element of an array, I then I incremented it to go through all my data. This was way too slow. So the only other option I found originally was to hand code in c# the calculations inside a loop. Then I simply recompiled each time I changed my math. This was terribly slow to do and I had to order everything correctly so things would update correctly (dependencies). I could have also used events, but hand coding events for each cell like calculation would also be very slow. Next I created an application to read Excel and to perfectly imitate it. Which is what I now use. Basically I write formulas onto a fraction of my data to get live results inside excel. Then my program reads excel, writes another c# program, compiles it, and runs that program which runs my excel created formulas through a lot more data a whole lot faster. The advantage being my application dependency sorts everything (or I could use events) so I don't have to (like excel does) And of course the speed. But now its not a single application anymore. Instead its 2 applications, one which only reads my formulas and writes another program. The other one being the result which only lives for a short while before I do other runs through my data with different formulas / settings. So I can't see multiple results at one time without introducing even more programs like a database or at least having the 2 applications talking to each other. My idea was to have a dll that would be written, compiled, loaded, and unloaded again and again. So a self-updating program, sort of. But apparently that's not possible without another appdomain which means data has to be marshaled to be moved between the appdomains. Which would slow things down, not for summaries, but for other stuff I need to do with all my data. I'm also forgetting to mention a huge problem with restarting an application again and again which is having to reload ALL my data into memory again and again. But its still a whole lot faster than excel. I'm really super puzzled as to what people do when they want to research data fast. I'm completely unable to have a program accept user input and having it fast. My understanding is that it would have to do things like excel which is to evaluate strings again and again. So my only option is to repeatedly compile applications. Do I have a correct understanding on computer science? I've only just began programming, and didn't think I would have to learn much to do some simple math on data. My understanding is its either compiling my user defined stuff to a program or evaluating them from a string or something stupid again and again. And my only option is to probably switch operating systems or something to be able to have a program compile and run itself without stopping (writing/compiling dll, loading dll to program, unloading, and repeating). Can someone give me some idea on how computers work? Is anything better possible? Like a running program, that can accept user input and compile it and then unload it later? I mean heck operating systems dont need to be RESTARTED with every change to user input. What is this the cave man days? Sorry, it's just so super frustrating not knowing what one can do, and can't do. If only I could understand and learn this stuff fast enough.

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  • bulk insert and update with ADO.NET Entity Framework

    - by Keith Barrows
    I am writing a small application that does a lot of feed processing. I want to use LINQ EF for this as speed is not an issue, it is a single user app and, in the end, will only be used once a month. My questions revolves around the best way to do bulk inserts using LINQ EF. After parsing the incoming data stream I end up with a List of values. Since the end user may end up trying to import some duplicate data I would like to "clean" the data during insert rather than reading all the records, doing a for loop, rejecting records, then finally importing the remainder. This is what I am currently doing: DateTime minDate = dataTransferObject.Min(c => c.DoorOpen); DateTime maxDate = dataTransferObject.Max(c => c.DoorOpen); using (LabUseEntities myEntities = new LabUseEntities()) { var recCheck = myEntities.ImportDoorAccess.Where(a => a.DoorOpen >= minDate && a.DoorOpen <= maxDate).ToList(); if (recCheck.Count > 0) { foreach (ImportDoorAccess ida in recCheck) { DoorAudit da = dataTransferObject.Where(a => a.DoorOpen == ida.DoorOpen && a.CardNumber == ida.CardNumber).First(); if (da != null) da.DoInsert = false; } } ImportDoorAccess newIDA; foreach (DoorAudit newDoorAudit in dataTransferObject) { if (newDoorAudit.DoInsert) { newIDA = new ImportDoorAccess { CardNumber = newDoorAudit.CardNumber, Door = newDoorAudit.Door, DoorOpen = newDoorAudit.DoorOpen, Imported = newDoorAudit.Imported, RawData = newDoorAudit.RawData, UserName = newDoorAudit.UserName }; myEntities.AddToImportDoorAccess(newIDA); } } myEntities.SaveChanges(); } I am also getting this error: System.Data.UpdateException was unhandled Message="Unable to update the EntitySet 'ImportDoorAccess' because it has a DefiningQuery and no element exists in the element to support the current operation." Source="System.Data.SqlServerCe.Entity" What am I doing wrong? Any pointers are welcome.

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  • UnauthorizedAccessException on MemoryMappedFile in C# 4.

    - by Kevin Nisbet
    Hey, I wanted to play around with using a MemoryMappedFile to access an existing binary file. If this even at all possible or am I a crazy person? The idea would be to map the existing binary file directly to memory for some preferably higher-speed operations. Or to atleast see how these things worked. using System.IO.MemoryMappedFiles; System.IO.FileInfo fi = new System.IO.FileInfo(@"C:\testparsercap.pcap"); MemoryMappedFileSecurity sec = new MemoryMappedFileSecurity(); System.IO.FileStream file = fi.Open(System.IO.FileMode.Open, System.IO.FileAccess.ReadWrite, System.IO.FileShare.ReadWrite); MemoryMappedFile mf = MemoryMappedFile.CreateFromFile(file, "testpcap", fi.Length, MemoryMappedFileAccess.Read, sec, System.IO.HandleInheritability.Inheritable, true); MemoryMappedViewAccessor FileMapView = mf.CreateViewAccessor(); PcapHeader head = new PcapHeader(); FileMapView.Read<PcapHeader>(0, out head); I get System.UnauthorizedAccessException was unhandled (Message=Access to the path is denied.) on the mf.CreateViewAccessor() line. I don't think it's file-permissions, since I'm running as a nice insecure administrator user, and there aren't any other programs open that might have a read-lock on the file. This is on Vista with UAC disabled. If it's simply not possible and I missed something in the documentation, please let me know. I could barely find anything at all referencing this feature of .net 4.0 Thanks!

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  • Stateful vs. Stateless Webservices

    - by chrsk
    Imagine a more complex CRUD application which has a three-tier-architecture and communicates over webservices. The client starts a conversation to the server and doing some wizard like stuff. To process the wizard the client needs feedback given by the server. We started a discussion about stateful or stateless webservices for this approach. I made some research combined with my own experience, which points me to the question mentioned later. Stateless webservices having the following properties (in our case): + high scalability + high availability + high speed + rapid testing - bloated contract - implementing more logic on server-side But we can cross out the first two points, our application doesn't needs high scalability and availability. So we come to the stateful webservice. I've read a bunch of blogs and forum posts and the most invented point implementing a stateful webservice was: + simplifies contract (protocol) - bad testing - runs counter to the basic architecture of http But doesn't almost all web applications have these bad points? Web applications uses cookies, query strings, session ids, and all the stuff to avoid the statelessness of http. So why is it that bad for webservices?

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  • How much multiple style sheets slow down to website?

    - by metal-gear-solid
    Here is 3 css file (one is only for IE) <link rel="stylesheet" href="css/blueprint/screen.css" type="text/css" media="screen, projection"> <link rel="stylesheet" href="css/blueprint/print.css" type="text/css" media="print"> <!--[if lt IE 8]><link rel="stylesheet" href="css/blueprint/ie.css" type="text/css" media="screen, projection"><![endif]--> If i keep divide scree.css into these css in my website Now it will be 6 css ( one is only for IE) <link rel="stylesheet" href="css/blueprint/reset.css" type="text/css" media="screen, projection"> <link rel="stylesheet" href="css/blueprint/grid.css" type="text/css" media="screen, projection"> <link rel="stylesheet" href="css/blueprint/typography.css" type="text/css" media="screen, projection"> <link rel="stylesheet" href="css/blueprint/forms.css" type="text/css" media="screen, projection"> <link rel="stylesheet" href="css/blueprint/print.css" type="text/css" media="print"> <!--[if lt IE 8]><link rel="stylesheet" href="css/blueprint/ie.css" type="text/css" media="screen, projection"><![endif]--> If i go for method two for a website even after production . Does it really slowdown the website page loading speed? if yes then how much? How much these 3 extra style sheet will affect site performance?

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  • How to Link VS2010 Database Project and LINQ to SQL

    - by Jason
    As I am working with the new database projects in VS2010, and as I am learning LINQ to SQL, I am curious as to the best way to link the two groups of information so that when I update one, the other updates along with it. From my research here at SO, as well as in Google, it appears the general rule of thumb is: "Build the database, and then create your LINQ to SQL classes." Of course, if I make a change in my database, the LINQ to SQL doesn't update automatically and I have to do it by hand. This is fairly simple right now as my database is small, but I am curious if there is an easier way for this to happen. In addition, the LINQ to SQL tool is pretty nice. The ability to create tables, add associations, and even create inheritance is very simple. As my second question, I am curious as to whether or not VS2010 can work the other way - I design the database in the DBLM file and then link it back to my database project. I appreciate any help with either of these two questions. I'm really interested in making this as easy as possible to reduce errors during development and improve the speed at which changes can be made.

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  • Why isn't uploadify and asp.net mvc 2 playing nice for me?

    - by Paperino
    First of all, I've checked out all the SO threads, and googled my brains out. I must be missing something obvious. I'd really appreciate some help! This is what I've got. UploadController.cs using System.Web; using System.Web.Mvc; namespace NIMDocs.Controllers { public class UploadController : Controller { public ActionResult Index() { return View(); } public string Procssed(HttpPostedFileBase FileData) { // DO STUFF return "DUHR I AM SMART"; } } } Index for Upload <%@ Page Language="C#" Inherits="System.Web.Mvc.ViewPage" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" > <head> <title>ITS A TITLE </title> <script src="../../Content/jqueryPlugins/uploadify/jquery-1.3.2.min.js" type="text/javascript"></script> <script src="../../Content/jqueryPlugins/uploadify/swfobject.js" type="text/javascript"></script> <script src="../../Content/jqueryPlugins/uploadify/jquery.uploadify.v2.1.0.min.js" type="text/javascript"></script> <script type="text/javascript"> $(document).ready(function () { $('#uploadify').fileUpload({ 'uploader': '../../Content/jqueryPlugins/uploadify/uploadify.swf', 'script': '/Upload/Processed', 'folder': '/uploads', 'multi': 'true', 'buttonText': 'Browse', 'displayData': 'speed', 'simUploadLimit': 2, 'cancelImg': '/Content/Images/cancel.png' }); }); </script> </head> <body> <input type="file" name="uploadify" id="uploadify" /> <p><a href="javascript:jQuery('#uploadify').uploadifyClearQueue()">Cancel All Uploads</a></p> </body> </html> What am I missing here? I've tried just about every path permutation for uploadify's "uploader" option. Absolute path, '/' prefixed, etc.

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  • MP3 Decoding on Android

    - by Rob Szumlakowski
    Hi. We're implementing a program for Android phones that plays audio streamed from the internet. Here's approximately what we do: Download a custom encrypted format. Decrypt to get chunks of regular MP3 data. Decode MP3 data to raw PCM data in a memory buffer. Pipe the raw PCM data to an AudioTrack Our target devices so far are Droid and Nexus One. Everything works great on Nexus One, but the MP3 decode is too slow on Droid. The audio playback starts to skip if we put the Droid under load. We are not permitted to decode the MP3 data to SD card, but I know that's not our problem anyways. We didn't write our own MP3 decoder, but used MPADEC (http://sourceforge.net/projects/mpadec/). It's free and was easy to integrate with our program. We compile it with the NDK. After exhaustive analysis with various profiling tools, we're convinced that it's this decoder that is falling behind. Here's the options we're thinking about: Find another MP3 decoder that we can compile with the Android NDK. This MP3 decoder would have to be either optimized to run on mobile ARM devices or maybe use integer-only math or some other optimizations to increase performance. Since the built-in Android MediaPlayer service will take URLs, we might be able to implement a tiny HTTP server in our program and serve the MediaPlayer with the decrypted MP3s. That way we can take advantage of the built-in MP3 decoder. Get access to the built-in MP3 decoder through the NDK. I don't know if this is possible. Does anyone have any suggestions on what we can do to speed up our MP3 decoding? -- Rob Sz

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  • Can aptitude for learning Programming paradigms be influenced by culture or native language's gramma

    - by DVK
    It is well known that different people have different aptitudes regarding various programming paradigms (e.g. some people have trouble learning non-procedural, especially functional languages. Some people have trouble understanding pointers - see Joel Spolsky's blog for musings on that. Some people have trouble grasping recursion). I was recently reading about a study that looked at how the grammar of someone's native language affected their speed of learning math. Can't find that article now but a quick googling found this reference. That led me to wondering whether someone's native culture or first language might affect their aptitude towards various programming paradigms. I'm more curious about positive influences - e.g. some trait that make it easier/faster for someone to learn a particular paradigm, for example native language grammar being very recursion-oriented. To be clear, I'm looking for how culture/language grammare may affect the difference between aptitude of the same person towards various paradigms as opposed to how it affects overall aptitude towards programming between different persons. Important: the only answers I'm interested in are either references to scientific studies, or personal observations from someone intimately familiar with a particular culture/language, including from their own experience. E.g. I'm not interested in your opinion of how Chinese being your first language affects anything unless you speak Chinese or worked with extremely large set of Chinese-native programmers extensively. I'm OK with your guesstimates not based on scientific studies, but please be sure to supply your reasoning about plausible causes of your observation. I'm not interested in culture-bashing (any such commends will be deleted or flagged for deletion). I'm also not particularly interested in culture-building - we all know Linus is from Finland and Tetris was written in Russia and Larry Wall is an American. Any culture/nation can produce a brilliant mind in any discipline. I'm interested in averages.

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  • Jquery cycle plugin image resizing issue opera

    - by Sam Gregory
    I am using the cycle plugin within Joomla and it works fine on IE6,FF,SAFARI,CHROME however when you view it in OPERA breaking happens. It loads fine but when it brings in the next slide and every consequent slide after that it re-sizes them to what i can only assume to be the browswe window's width and height. here's my javascript <script type="text/javascript"> $('.fullScreen').cycle({ speed: 1000, timeout: 100 }); </script> css <script type="text/css"> .fullScreen { margin-left: 0px; height: 355px; clear: both; width: 475px; z-index: -1; overflow: hidden; } </script> and finally HTML <div class="fullscreen"> <img width="475px" src="images/someimage1.jpg" /> <img width="475px" src="images/someimage2.jpg" /> <img width="475px" src="images/someimage3.jpg" /> </div> hope I'm not the only one having this problem.

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  • WCF Named Pipe IPC

    - by Peter M
    I have been trying to get up to speed on Named Pipes this week. The task I am trying to solve with them is that I have an existing windows service that is acting as a device driver that funnels data from an external device into a database. Now I have to modify this service and add an optional user front end (on the same machine, using a form of IPC) that can monitor the data as it passes between the device and the DB as well as send some commands back to the service. My initial ideas for the IPC were either named pipes or memory mapped files. So far I have been working through the named pipe idea using WCF Tutorial Basic Interprocess Communication . My idea is to set the Windows service up with an additional thread that implements the WCF NamedPipe Service and use that as a conduit to the internals of my driver. I have the sample code working, however I can not get my head around 2 issues that I am hoping that someone here can help me with: In the tutorial the ServiceHost is instantiated with a typeof(StringReverser) rather than by referencing a concrete class. Thus there seems to be no mechanism for the Server to interact with the service itself (between the host.Open() and host.Close() lines). Is it possible to create a link between and pass information between the server and the class that actually implements the service? If so, how? If I run a single instance of the server and then run multiple instance of the clients, it seems that each client gets a separate instance of the service class. I tried adding some state information to the class implementing the service and it was only retained within the instance of the named pipe. This is possibly related to the first question, but is there anyway to force the named pipes to use the same instance of the class that is implementing the service? Finally, any thoughts on MMF vs Named Pipes? Thanks for you help

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  • Using JavaScript/jQuery to return a list of CSS selectors based on highlighted text

    - by Bungle
    I've been given some project requirements that involve (ideally) returning a list of CSS selectors based on highlighted text. In other words, a user could do something like this on a page: Click a button to indicate that their next text selection should be recorded. Highlight some text on the page. See a generated list of CSS selectors that correspond to all the elements that contain the highlighted text. Firstly, does this seem like a feasible goal? jQuery makes it easy to use a selector to access a particular element, but I'm not sure if the reverse holds true. If an element lacks an id attribute, I also don't know how you'd return an "optimized" selector - i.e., one that identifies an element uniquely. Maybe crawl up the DOM until you find an ID, then stem the selector from there? Secondly, from a high-level perspective, any ideas on how to go about this? Any tips or tricks that could speed development? I very much appreciate any help. Thanks!

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  • How do you construct an array suitable for numpy sorting?

    - by Alex
    I need to sort two arrays simultaneously, or rather I need to sort one of the arrays and bring the corresponding element of its associated array with it as I sort. That is if the array is [(5, 33), (4, 44), (3, 55)] and I sort by the first axis (labeled below dtype='alpha') then I want: [(3.0, 55.0) (4.0, 44.0) (5.0, 33.0)]. These are really big data sets and I need to sort first ( for nlog(n) speed ) before I do some other operations. I don't know how to merge my two separate arrays though in the proper manner to get the sort algorithm working. I think my problem is rather simple. I tried three different methods: import numpy x=numpy.asarray([5,4,3]) y=numpy.asarray([33,44,55]) dtype=[('alpha',float), ('beta',float)] values=numpy.array([(x),(y)]) values=numpy.rollaxis(values,1) #values = numpy.array(values, dtype=dtype) #a=numpy.array(values,dtype=dtype) #q=numpy.sort(a,order='alpha') print "Try 1:\n", values values=numpy.empty((len(x),2)) for n in range (len(x)): values[n][0]=y[n] values[n][1]=x[n] print "Try 2:\n", values #values = numpy.array(values, dtype=dtype) #a=numpy.array(values,dtype=dtype) #q=numpy.sort(a,order='alpha') ### values = [(x[0], y[0]), (x[1],y[1]) , (x[2],y[2])] print "Try 3:\n", values values = numpy.array(values, dtype=dtype) a=numpy.array(values,dtype=dtype) q=numpy.sort(a,order='alpha') print "Result:\n",q I commented out the first and second trys because they create errors, I knew the third one would work because that was mirroring what I saw when I was RTFM. Given the arrays x and y (which are very large, just examples shown) how do I construct the array (called values) that can be called by numpy.sort properly? *** Zip works great, thanks. Bonus question: How can I later unzip the sorted data into two arrays again?

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  • Wpf: Why is WriteableBitmap getting slower?

    - by fritz
    There is a simple MSDN example about WriteableBitmap. It shows how to draw a freehand line with the cursor by just updating one pixel when the mouse is pressed and is moving over a WPF -Image Control. writeableBitmap.Lock(); (...set the writeableBitmap.BackBuffers pixel value...) writeableBitmap.AddDirtyRect(new Int32Rect(column, row, 1, 1)); writeableBitmap.Unlock(); Now I'm trying to understand the following behaviour when moving the mouse pointer very fast: If the image/bitmap size is relatively small e.g. 800:600 pixel, then the last drawn pixel is always "synchronized" with the mouse pointers position, i.e. there is no delay, very fast reaction on mouse movements. But if the bitmap gets larger e.g. 1300:1050 pixel, you can notice a delay, the last drawn pixel always appear a bit delayed behind the moving mouse pointer. So as in both cases only one pixel gets updated with "AddDirtyRect", the reaction speed should be independent from the bitmap size!? But it seems that Writeablebitmap gets slower when it's size gets larger. Or does the whole bitmap somehow get transferred to the graphic device on every writeableBitmap.Unlock(); call , and not only the rectangle area speficied in the AddDirtyRect method? fritz

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  • Finding most efficient transmission size in varying network latency scenarios

    - by rwmnau
    I'm building a .NET remoting client/server that will be transmitting thousands of files, of varying sizes (everything from a few bytes to hundreds of MB), and I'm curious about a general method for finding the appropriate transmission size. As I see it, there's the following tradeoff: Serialize entire file into a transmission object and transmit at once, regardless of size. This would be the fastest, but a failure during tranmission requires that the whole file be re-transmitted. If the file size is larger than something small (like 4KB), break it into 4KB chunks and transmit those, re-assembling on the server. In addition to the complexity of this, it's slower because of continued round-trips and acknowledgements, though a failure of any one piece doesn't waste much time. The ideal transmission method (when taking into account negotiation latency vs. failure rate) is somewhere in between, and I'm wondering about how to find out the best size for that particular client. Do I have some dynamic tuning step in my transmission that looks at the current bytes/second average, and then raises the transmission size until the speed starts to drop (failures overwhelm negotiation cost)? Or is there some other method for determining ideal transmission size? The application will be multi-threaded, so number of threads also factors in to the calculation. I'm not looking for a formula (though I'll take one if you've got it), but just what to consider as I create this process.

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  • Improve XPath efficiency for repeated, parameterized queries

    - by Chris Allan
    Hi, I am repeatedly performing the following XPath query (though parameterized by 'keywordText') around 40,000 times: String query = SystemGlobal.YAHOO_KEYWORDSSUBNODE + "/" + SystemGlobal.YAHOO_KEYWORDNODE + "[" + SystemGlobal.YAHOO_ATTRKEYPHRASE + "='" + keywordText + "']"; CachedXPathAPI cachedXPathAPI = new CachedXPathAPI(); NodeIterator nl = cachedXPathAPI.selectNodeIterator(doc.getElementsByTagName(SystemGlobal.YAHOO_KEYWORDSROOT).item(0), query); Node n; if ((n = nl.nextNode()) != null) { keyword.setKeywordId(Long.parseLong(cachedXPathAPI.selectSingleNode(n, SystemGlobal.YAHOO_ATTRKEYID).getTextContent())); keyword.setKeyPhrase(cachedXPathAPI.selectSingleNode(n, SystemGlobal.YAHOO_ATTRKEYPHRASE).getTextContent()); keyword.setStatus(mapStatus(cachedXPathAPI.selectSingleNode(n, SystemGlobal.YAHOO_ATTRSTATUS).getTextContent())); keyword.setCampaignId(Long.parseLong(cachedXPathAPI.selectSingleNode(n, "../../" + SystemGlobal.YAHOO_ATTRCAMPAIGNID).getTextContent())); keyword.setAdGroupId(Long.parseLong(cachedXPathAPI.selectSingleNode(n, "../" + SystemGlobal.YAHOO_ATTRADGROUPID).getTextContent())); On the first run of the script, all 40,000 runs of this piece of code will have nl.nextNode() == null, and everything runs quite quickly. However, on the following runs, when nl.nextNode() != null, then things slow down a lot - this takes around an additional 40min to run (whereas the first run takes maybe 1 minute). Oh, and the doc is constructed like so: InputSource in = new InputSource(new FileInputStream(filename)); DocumentBuilderFactory dfactory = DocumentBuilderFactory.newInstance(); dfactory.setNamespaceAware(true); doc = dfactory.newDocumentBuilder().parse(in); I tried including the following lines reportEvaluator = new XPathEvaluatorImpl(reportDoc); reportResolver = reportEvaluator.createNSResolver(reportDoc); and rather creating a NodeIterator, instead creating an XPathResult: XPathResult result = (XPathResult)reportEvaluator.evaluate(query, doc.getElementsByTagName(SystemGlobal.YAHOO_KEYWORDSROOT).item(0), reportResolver, XPathResult.UNORDERED_NODE_ITERATOR_TYPE, null); however this ran even slower Is there a way in which I can speed up the running of this script? I have seen references to precompiled queries, though I haven't seen many actual details. Also, as seen in the code, I am using CachedXPathAPI, though the benefit for this case is not so great. Any help is much appreciated! Chris Allan

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  • What's slowing for loops/assignment vs. C?

    - by Lee
    I have a collection of PHP scripts that are extremely CPU intensive, juggling millions of calculations across hundreds of simultaneous users. I'm trying to find a way to speed up the internals of PHP variable assignment, and looping sequences vs C. Although PHP is obviously loosely typed, is there any way/extension to specifically assign type (assign, not cast, which seems even more expensive) in a C-style fashion? Here's what I mean. This is some dummy code in C: #include <stdio.h> int main() { unsigned long add=0; for(unsigned long x=0;x<100000000;x++) { add = x*59328409238; } printf("x is %ld\n",add); } Pretty self-explanatory -- it loops 100 million times, multiples each iteration by an arbitrary number of some 59 billion, assigns it to a variable and prints it out. On my Macbook, compiling it and running it produced: lees-macbook-pro:Desktop lee$ time ./test2 x is 5932840864471590762 real 0m0.266s user 0m0.253s sys 0m0.002s Pretty darn fast! A similar script in PHP 5.3 CLI... <?php for($i=0;$i<100000000;$i++){ $a=$i*59328409238; } echo $a."\n"; ?> ... produced: lees-macbook-pro:Desktop lee$ time /Applications/XAMPP/xamppfiles/bin/php test3.php 5.93284086447E+18 real 0m22.837s user 0m22.110s sys 0m0.078s Over 22 seconds vs 0.2! I realize PHP is doing a heck of a lot more behind the scenes than this simple C program - but is there any way to make the PHP internals to behave more 'natively' on primitive types and loops?

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  • Switching from ListView to VirtualStringTree

    - by Jeff
    Hey S.O! I am trying to build my projects with a VirtualStringTree rather than a Listview, because of the vast speed difference. The thing is, even after looking thru the demo's, I just can't figure out exactly how I would use it as a ListView. Like, adding, deleting, and basically just working with ListView items is so easy, but when I look at the VT, it gets almost too complicated. All I am looking for, is a VT that looks like a ListView, with subitems etc. Here are some routines using the ListView, that I would like to use with VT (This is just a pseudo example: procedure Add; begin with ListView.Items.Add do Begin Caption := EditCaption.Text; SubItems.Add(EditSubItem.Text): End; end; Procedure ReadItem(I : Integer); begin ShowMessage(ListView.Items[I].Caption); ShowMessage(ListView.Items[I].SubItems[0]); end; Of course, also the Delete function, but since thats like 1 line, I didnt bother :P Could anyone maybe translate the above examples into using a ListView style VT? Thanks!

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  • SQL MIN in Sub query causes huge delay

    - by Spencer
    I have a SQL query that I'm trying to debug. It works fine for small sets of data, but in large sets of data, this particular part of it causes it to take 45-50 seconds instead of being sub second in speed. This subquery is one of the select items in a larger query. I'm basically trying to figure out when the earliest work date is that fits in the same category as the current row we are looking at (from table dr) ISNULL(CONVERT(varchar(25),(SELECT MIN(drsd.DateWorked) FROM [TableName] drsd WHERE drsd.UserID = dr.UserID AND drsd.Val1 = dr.Val1 OR (((drsd.Val2 = dr.Val2 AND LEN(dr.Val2) > 0) AND (drsd.Val3 = dr.Val3 AND LEN(dr.Val3) > 0) AND (drsd.Val4 = dr.Val4 AND LEN(dr.Val4) > 0)) OR (drsd.Val5 = dr.Val5 AND LEN(dr.Val5) > 0) OR ((drsd.Val6 = dr.Val6 AND LEN(dr.Val6) > 0) AND (drsd.Val7 = dr.Val7 AND LEN(dr.Val2) > 0))))), '') AS WorkStartDate, This winds up executing a key lookup some 18 million times on a table that has 346,000 records. I've tried creating an index on it, but haven't had any success. Also, selecting a max value in this same query is sub second in time, as it doesn't have to execute very many times at all. Any suggestions of a different approach to try? Thanks!

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  • maven and lift using scala 2.8 : lift-mapper missing?

    - by Bjorn J
    Newbie question since I'm not up to speed using maven at all. I'm trying to use scala + lift using scala 2.8, environment is a win7 box if that matters. I create a basic project using: mvn archetype:generate -U -DarchetypeGroupId=net.liftweb -DarchetypeArtifactId=lift-archetype-basic -DarchetypeVersion=2.0-scala280-SNAPSHOT -DarchetypeRepository=http://scala-tools.org/repo-snapshots -DremoteRepositories=http://scala-tools.org/repo-snapshots -DgroupId=com.liftworkshop -DartifactId=todo -Dversion=1.0-SNAPSHOT So far so good, but then, I try to cd into my new project and do: mvn jetty:run I after quite a few downloads end up with a error like below: [ERROR] BUILD ERROR [INFO] ------------------------------------------------------------------------ [INFO] Failed to resolve artifact. Missing: ---------- 1) net.liftweb:lift-mapper:jar:2.0-scala280-SNAPSHOT Try downloading the file manually from the project website. Then, install it using the command: mvn install:install-file -DgroupId=net.liftweb -DartifactId=lift-mapper -D version=2.0-scala280-SNAPSHOT -Dpackaging=jar -Dfile=/path/to/file Alternatively, if you host your own repository you can deploy the file there: mvn deploy:deploy-file -DgroupId=net.liftweb -DartifactId=lift-mapper -Dve rsion=2.0-scala280-SNAPSHOT -Dpackaging=jar -Dfile=/path/to/file -Durl=[url] -Dr epositoryId=[id] Path to dependency: 1) com.liftworkshop:todo:war:1.0-SNAPSHOT 2) net.liftweb:lift-mapper:jar:2.0-scala280-SNAPSHOT ---------- 1 required artifact is missing. for artifact: com.liftworkshop:todo:war:1.0-SNAPSHOT from the specified remote repositories: scala-tools.snapshots (http://scala-tools.org/repo-snapshots), scala-tools.releases (http://scala-tools.org/repo-releases), central (http://repo1.maven.org/maven2) Any ideas?

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  • Is it possible to store ObjectContext on the client when using WCF and Entity Framework?

    - by Sergey
    Hello, I have a WCF service which performs CRUD operation on my data model: Add, Get, Update and Delete. And I'm using Entity Framework for my data model. On the other side there is a client application which calls methods of the WCF service. For example I have a Customer class: [DataContract] public class Customer { public Guid CustomerId {get; set;} public string CustomerName {get; set;} } and WCF service defines this method: public void AddCustomer(Customer c) { MyEntities _entities = new MyEntities(); _entities.AddToCustomers(c); _entities.SaveChanges(); } and the client application passes objects to the WCF service: var customer = new Customer(){CustomerId = Guid.NewGuid, CustomerName="SomeName"}; MyService svc = new MyService(); svc.Add(customer); // or svc.Update(customer) for example But when I need to pass a great amount of objects to the WCF it could be a perfomance issue because of I need to create ObjectContext each time when I'm doing Add(), Update(), Get() or Delete(). What I'm thinking on is to keep ObjectContext on the client and pass ObjectContext to the wcf methods as additional parameter. Is it possible to create and keep ObjectContext on the client and don't recreate it for each operation? If it is not, how could speed up the passing of huge amount of data to the wcf service? Sergey

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  • Can get coordinates from iPhone simulator, but can't get coordinates from iPhone device

    - by iPhoneARguy
    Hi everyone, I've run into something of a mysterious bug (to me). I have some code to pick out the user's current location on the iPhone SDK. It works fine on the iPhone simulator, but when I try to run it on the actual device, I get a weird error. Here is the code (I am using ASIFormDataRequest to create a POST request): ASIFormDataRequest * request = [ASIFormDataRequest requestWithURL:url]; [request setPostValue:@"testauthor" forKey:@"author"]; [request setPostValue:[[NSNumber numberWithDouble:datum.location.coordinate.latitude] stringValue] forKey:@"latitude"]; NSLog(@"%f", datum.location.coordinate.latitude); NSLog(@"%f", datum.location.coordinate.longitude); [request setPostValue:[[NSNumber numberWithDouble:datum.location.coordinate.longitude] stringValue] forKey:@"longitude"]; [request setPostValue:datum.comment forKey:@"comment"]; On the simulator, NSLog does log both the latitude and longitude, but on the iPhone, it does not. Even stranger, when I go through with the debugger on the device, I try "po datum.location", I get <+###, -###> +/- 223.10m (speed 0.00 mps / course -1.00) @ 2010-05-02 22:18:37 -0400 (### replaced by my location) but when I do "(gdb) po datum.location.coordinate" I get: There is no member named coordinate. Do you guys have any idea why this might happen? Thanks in advance for your help!

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  • Fastest way to remove non-numeric characters from a VARCHAR in SQL Server

    - by Dan Herbert
    I'm writing an import utility that is using phone numbers as a unique key within the import. I need to check that the phone number does not already exist in my DB. The problem is that phone numbers in the DB could have things like dashes and parenthesis and possibly other things. I wrote a function to remove these things, the problem is that it is slow and with thousands of records in my DB and thousands of records to import at once, this process can be unacceptably slow. I've already made the phone number column an index. I tried using the script from this post: http://stackoverflow.com/questions/52315/t-sql-trim-nbsp-and-other-non-alphanumeric-characters But that didn't speed it up any. Is there a faster way to remove non-numeric characters? Something that can perform well when 10,000 to 100,000 records have to be compared. Whatever is done needs to perform fast. Update Given what people responded with, I think I'm going to have to clean the fields before I run the import utility. To answer the question of what I'm writing the import utility in, it is a C# app. I'm comparing BIGINT to BIGINT now, with no need to alter DB data and I'm still taking a performance hit with a very small set of data (about 2000 records). Could comparing BIGINT to BIGINT be slowing things down? I've optimized the code side of my app as much as I can (removed regexes, removed unneccessary DB calls). Although I can't isolate SQL as the source of the problem anymore, I still feel like it is.

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  • Tips on creating user interfaces and optimizing the user experience

    - by Saif Bechan
    I am currently working on a project where a lot of user interaction is going to take place. There is also a commercial side as people can buy certain items and services. In my opinion a good blend of user interface, speed and security is essential for these types of websites. It is fairly easy to use ajax and JavaScript nowadays to do almost everything, as there are a lot of libraries available such as jQuery and others. But this can have some performance and incompatibility issues. This can lead to users just going to the next website. The overall look of the website is important too. Where to place certain buttons, where to place certain types of articles such as faq and support. Where and how to display error messages so that the user sees them but are not bothering him. And an overall color scheme is important too. The basic question is: How to create an interface that triggers a user to buy/use your services I know psychology also plays a huge role in how users interact with your website. The color scheme for example is important. When the colors are irritating on a website you just want to click away. I have not found any articles that explain those concept. Does anyone have any tips and/or recourses where i can get some articles that guide you in making the correct choices for your website.

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