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  • How to quickly acquire and process real time screen output

    - by Akusete
    I am trying to write a program to play a full screen PC game for fun (as an experiment in Computer Vision and Artificial Intelligence). For this experiment I am assuming the game has no underlying API for AI players (nor is the source available) so I intend to process the visual information rendered by the game on the screen. The game runs in full screen mode on a win32 system (direct-X I assume). Currently I am using the win32 functions #include <windows.h> #include <cvaux.h> class Screen { public: HWND windowHandle; HDC windowContext; HBITMAP buffer; HDC bufferContext; CvSize size; uchar* bytes; int channels; Screen () { windowHandle = GetDesktopWindow(); windowContext = GetWindowDC (windowHandle); size = cvSize (GetDeviceCaps (windowContext, HORZRES), GetDeviceCaps (windowContext, VERTRES)); buffer = CreateCompatibleBitmap (windowContext, size.width, size.height); bufferContext = CreateCompatibleDC (windowContext); SelectObject (bufferContext, buffer); channels = 4; bytes = new uchar[size.width * size.height * channels]; } ~Screen () { ReleaseDC(windowHandle, windowContext); DeleteDC(bufferContext); DeleteObject(buffer); delete[] bytes; } void CaptureScreen (IplImage* img) { BitBlt(bufferContext, 0, 0, size.width, size.height, windowContext, 0, 0, SRCCOPY); int n = size.width * size.height; int imgChannels = img->nChannels; GetBitmapBits (buffer, n * channels, bytes); uchar* src = bytes; uchar* dest = (uchar*) img->imageData; uchar* end = dest + n * imgChannels; while (dest < end) { dest[0] = src[0]; dest[1] = src[1]; dest[2] = src[2]; dest += imgChannels; src += channels; } } The rate at which I can process frames using this approach is much to slow. Is there a better way to acquire screen frames?

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  • mciSendString cannot save to directory path

    - by robUK
    Hello, VS C# 2008 SP1 I have a created a small application that records and plays audio. However, my application needs to save the wave file to the application data directory on the users computer. The mciSendString takes a C style string as a parameter and has to be in 8.3 format. However, my problem is I can't get it to save. And what is strange is sometime it does and sometimes it doesn't. Howver, most of the time is failes. However, if I save directly to the C drive it works first time everything. I have used 3 different methods that I have coded below. The error number that I get when it fails is 286."The file was not saved. Make sure your system has sufficient disk space or has an intact network connection" Many thanks for any suggestins, [DllImport("winmm.dll",CharSet=CharSet.Auto)] private static extern uint mciSendString([MarshalAs(UnmanagedType.LPTStr)] string command, StringBuilder returnValue, int returnLength, IntPtr winHandle); [DllImport("winmm.dll", CharSet = CharSet.Auto)] private static extern int mciGetErrorString(uint errorCode, StringBuilder errorText, int errorTextSize); [DllImport("Kernel32.dll", CharSet=CharSet.Auto)] private static extern int GetShortPathName([MarshalAs(UnmanagedType.LPTStr)] string longPath, [MarshalAs(UnmanagedType.LPTStr)] StringBuilder shortPath, int length); // Stop recording private void StopRecording() { // Save recorded voice string shortPath = this.shortPathName(); string formatShortPath = string.Format("save recsound \"{0}\"", shortPath); uint result = 0; StringBuilder errorTest = new StringBuilder(256); // C:\DOCUME~1\Steve\APPLIC~1\Test.wav // Fails result = mciSendString(string.Format("{0}", formatShortPath), null, 0, IntPtr.Zero); mciGetErrorString(result, errorTest, errorTest.Length); // command line convention - fails result = mciSendString("save recsound \"C:\\DOCUME~1\\Steve\\APPLIC~1\\Test.wav\"", null, 0, IntPtr.Zero); mciGetErrorString(result, errorTest, errorTest.Length); // 8.3 short format - fails result = mciSendString(@"save recsound C:\DOCUME~1\Steve\APPLIC~1\Test.wav", null, 0, IntPtr.Zero); mciGetErrorString(result, errorTest, errorTest.Length); // Save to C drive works everytime. result = mciSendString(@"save recsound C:\Test.wav", null, 0, IntPtr.Zero); mciGetErrorString(result, errorTest, errorTest.Length); mciSendString("close recsound ", null, 0, IntPtr.Zero); } // Get the short path name so that the mciSendString can save the recorded wave file private string shortPathName() { string shortPath = string.Empty; long length = 0; StringBuilder buffer = new StringBuilder(256); // Get the length of the path length = GetShortPathName(this.saveRecordingPath, buffer, 256); shortPath = buffer.ToString(); return shortPath; }

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  • Autoloading Development or Production configs (best practices)

    - by Xeoncross
    When programming sites you usually have one set of config files for the development environment and another set for the production server (or one file with both settings). I am assuming all projects should be handled by version control like git or svn. Manual file transfers (like FTP) is wrong on so many levels. How you enable/disable the correct settings (so that your system knows which ones to use) is a problem for me. Each system I work on just kind of jimmy-rigs a solution. Below are the 3 methods I know of and I am hoping that someone can submit a more elegant solutions. 1) File Based The system loads a folder structure based on the URL requested. /site.com /site.fakeTLD /lib index.php For example, if the url is http://site.com then the system loads the production config files located in the site.com folder. However, if I'm working on the site locally I visit http://site.fakeTLD to work on the local copy of the site. To setup this I edit my hosts file and add site.fakeTLD to point to my own computer (127.0.0.1/localhost) and then create a vhost in apache. So now I can work on the codebase locally and then push to the server without any trouble. The problem is that this is susceptible to a "host" injection attack. So someone loading site.com could set the host to site.fakeTLD and then the system would load my development config files instead of production. 2) Config Based The config files contain on section for development - and one for production. The problem is that each time you go to push your changes to the repo you have to edit the file to specify which set of config options should be used. $use = 'production'; //'development'; This leaves the repo open to human error should one of the developers forget to enable the right setting. 3) File System Check Based All the development machines have an extra empty file called "development.txt" or something. Each time the system loads it checks for this file - if found then it knows it is in development mode - if missing then it knows it is in production mode. Since the file is NEVER ADDED to the repo then it will never be pushed (and checked out) on the production machine. However, this just doesn't feel right and causes a slight slow down since all filesystem checks are slow. Is there anyway that the server can auto-detect wither to use the development or production configs?

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  • Installing PyGraphViz on Windows, Python 2.7

    - by user574043
    I can't install pygraphviz on Windows XP. I'm using Python27. Before to launch the setup I've changet these two variables of the setup.py file library_path="C:\\Archivos de programa\\Graphviz 2.28\\bin" include_path="C:\\Archivos de programa\\Graphviz 2.28\\include\\graphviz" Then I've launched the setup. I'm using mingw32 as a compiler. I don't know what can I do now. I'm using the following command: C:\Python27\pygraphviz-1.1>c:\python27\python setup.py build -c mingw32 And I've got the folling result library_path=C:\Archivos de programa\Graphviz 2.28\bin include_path=C:\Archivos de programa\Graphviz 2.28\include\graphviz running build running build_py running build_ext building 'pygraphviz._graphviz' extension C:\MinGW\bin\gcc.exe -mno-cygwin -mdll -O -Wall "-IC:\Archivos de programa\Graphviz 2.28\include\graphviz" -Ic:\python27\include -Ic:\python 27\PC -c pygraphviz/graphviz_wrap.c -o build\temp.win32-2.7\Release\pygraphviz\graphviz_wrap.o pygraphviz/graphviz_wrap.c: In function 'agattr_label': pygraphviz/graphviz_wrap.c:2855:5: warning: return makes integer from pointer without a cast writing build\temp.win32-2.7\Release\pygraphviz\_graphviz.def Traceback (most recent call last): File "setup.py", line 146, in <module> package_data = package_data File "c:\python27\lib\distutils\core.py", line 152, in setup dist.run_commands() File "c:\python27\lib\distutils\dist.py", line 953, in run_commands self.run_command(cmd) File "c:\python27\lib\distutils\dist.py", line 972, in run_command cmd_obj.run() File "c:\python27\lib\distutils\command\build.py", line 127, in run self.run_command(cmd_name) File "c:\python27\lib\distutils\cmd.py", line 326, in run_command self.distribution.run_command(command) File "c:\python27\lib\distutils\dist.py", line 972, in run_command cmd_obj.run() File "c:\python27\lib\distutils\command\build_ext.py", line 340, in run self.build_extensions() File "c:\python27\lib\distutils\command\build_ext.py", line 449, in build_extensions self.build_extension(ext) File "c:\python27\lib\distutils\command\build_ext.py", line 531, in build_extension target_lang=language) File "c:\python27\lib\distutils\ccompiler.py", line 741, in link_shared_object extra_preargs, extra_postargs, build_temp, target_lang) File "c:\python27\lib\distutils\cygwinccompiler.py", line 260, in link target_lang) File "c:\python27\lib\distutils\unixccompiler.py", line 218, in link libraries) File "c:\python27\lib\distutils\ccompiler.py", line 1121, in gen_lib_options opt = compiler.runtime_library_dir_option(dir) File "c:\python27\lib\distutils\unixccompiler.py", line 285, in runtime_library_dir_option compiler = os.path.basename(sysconfig.get_config_var("CC")) File "c:\python27\lib\ntpath.py", line 198, in basename return split(p)[1] File "c:\python27\lib\ntpath.py", line 170, in split d, p = splitdrive(p) File "c:\python27\lib\ntpath.py", line 125, in splitdrive if p[1:2] == ':': TypeError: 'NoneType' object is not subscriptable Any idea on how to solve it over windows? In other computer with Ubuntu I've installed without problems.

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  • Compile error with acml.h

    - by Aslan986
    I'm having some problem compiling a Visual Studio 2008 project in which I use acml.h. I correctly installed amcl package on my computer, version 5.1.0-ifort64. I added the reference to the acml.h directory in Visual Studio Compiler Properties, but when i try to compile i get these errors: 1>C:\AMD\acml5.1.0\ifort64_mp\include\acml.h(1510) : error C2144: errore di sintassi: 'char' deve essere preceduto da ')' 1>C:\AMD\acml5.1.0\ifort64_mp\include\acml.h(1510) : error C2144: errore di sintassi: 'char' deve essere preceduto da ';' 1>C:\AMD\acml5.1.0\ifort64_mp\include\acml.h(1510) : warning C4091: '': ignorato a sinistra di 'char' quando non si dichiara alcuna variabile 1>C:\AMD\acml5.1.0\ifort64_mp\include\acml.h(1510) : error C2143: errore di sintassi: ';' mancante prima di ',' 1>C:\AMD\acml5.1.0\ifort64_mp\include\acml.h(1510) : error C2059: errore di sintassi: ',' 1>C:\AMD\acml5.1.0\ifort64_mp\include\acml.h(1510) : error C2059: errore di sintassi: ')' 1>C:\AMD\acml5.1.0\ifort64_mp\include\acml.h(1675) : error C2144: errore di sintassi: 'char' deve essere preceduto da ')' 1>C:\AMD\acml5.1.0\ifort64_mp\include\acml.h(1675) : error C2144: errore di sintassi: 'char' deve essere preceduto da ';' 1>C:\AMD\acml5.1.0\ifort64_mp\include\acml.h(1675) : warning C4091: '': ignorato a sinistra di 'char' quando non si dichiara alcuna variabile 1>C:\AMD\acml5.1.0\ifort64_mp\include\acml.h(1675) : error C2143: errore di sintassi: ';' mancante prima di ',' 1>C:\AMD\acml5.1.0\ifort64_mp\include\acml.h(1675) : error C2059: errore di sintassi: ',' 1>C:\AMD\acml5.1.0\ifort64_mp\include\acml.h(1675) : error C2059: errore di sintassi: ')' 1>C:\AMD\acml5.1.0\ifort64_mp\include\acml.h(3511) : error C2144: errore di sintassi: 'char' deve essere preceduto da ')' 1>C:\AMD\acml5.1.0\ifort64_mp\include\acml.h(3511) : error C2144: errore di sintassi: 'char' deve essere preceduto da ';' 1>C:\AMD\acml5.1.0\ifort64_mp\include\acml.h(3511) : warning C4091: '': ignorato a sinistra di 'char' quando non si dichiara alcuna variabile 1>C:\AMD\acml5.1.0\ifort64_mp\include\acml.h(3511) : error C2143: errore di sintassi: ';' mancante prima di ',' 1>C:\AMD\acml5.1.0\ifort64_mp\include\acml.h(3511) : error C2059: errore di sintassi: ',' 1>C:\AMD\acml5.1.0\ifort64_mp\include\acml.h(3511) : error C2059: errore di sintassi: ')' 1>C:\AMD\acml5.1.0\ifort64_mp\include\acml.h(3676) : error C2144: errore di sintassi: 'char' deve essere preceduto da ')' 1>C:\AMD\acml5.1.0\ifort64_mp\include\acml.h(3676) : error C2144: errore di sintassi: 'char' deve essere preceduto da ';' 1>C:\AMD\acml5.1.0\ifort64_mp\include\acml.h(3676) : warning C4091: '': ignorato a sinistra di 'char' quando non si dichiara alcuna variabile 1>C:\AMD\acml5.1.0\ifort64_mp\include\acml.h(3676) : error C2143: errore di sintassi: ';' mancante prima di ',' 1>C:\AMD\acml5.1.0\ifort64_mp\include\acml.h(3676) : error C2059: errore di sintassi: ',' 1>C:\AMD\acml5.1.0\ifort64_mp\include\acml.h(3676) : error C2059: errore di sintassi: ')' I apologize for italian language; however they are all sintax errors. How can I fix it? Can someone help me?

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  • Is this asking too much of a browser?

    - by Matt Ball
    I'm embedding a large array in <script> tags in my HTML, like this (nothing surprising): <script> var largeArray = [/* lots of stuff in here */]; </script> In this particular example, the array has 210,000 elements. That's well below the theoretical maximum of 231 - by 4 orders of magnitude. Here's the fun part: if I save JS source for the array to a file, that file is 44 megabytes (46,573,399 bytes, to be exact). If you want to see for yourself, you can download it from my Dropbox. (All the data in there is canned, so much of it is repeated. This will not be the case in production.) Now, I'm really not concerned about serving that much data. My server gzips its responses, so it really doesn't take all that long to get the data over the wire. However, there is a really nasty tendency for the page, once loaded, to crash the browser. I'm not testing at all in IE (this is an internal tool). My primary targets are Chrome 8 and Firefox 3.6. In Firefox, I can see a reasonably useful error in the console: Error: script stack space quota is exhausted In Chrome, I simply get the sad-tab page: Cut to the chase, already Is this really too much data for our modern, "high-performance" browsers to handle? Is there anything I can do* to gracefully handle this much data? Incidentally, I was able to get this to work (read: not crash the tab) on-and-off in Chrome. I really thought that Chrome, at least, was made of tougher stuff, but apparently I was wrong... Edit 1 @Crayon: I wasn't looking to justify why I'd like to dump this much data into the browser at once. Short version: either I solve this one (admittedly not-that-easy) problem, or I have to solve a whole slew of other problems. I'm opting for the simpler approach for now. @various: right now, I'm not especially looking for ways to actually reduce the number of elements in the array. I know I could implement Ajax paging or what-have-you, but that introduces its own set of problems for me in other regards. @Phrogz: each element looks something like this: {dateTime:new Date(1296176400000), terminalId:'terminal999', 'General___BuildVersion':'10.05a_V110119_Beta', 'SSM___ExtId':26680, 'MD_CDMA_NETLOADER_NO_BCAST___Valid':'false', 'MD_CDMA_NETLOADER_NO_BCAST___PngAttempt':0} @Will: but I have a computer with a 4-core processor, 6 gigabytes of RAM, over half a terabyte of disk space ...and I'm not even asking for the browser to do this quickly - I'm just asking for it to work at all! ? *other than the obvious: sending less data to the browser

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  • How to Practice Unix Programming in C?

    - by danben
    After five years of professional Java (and to a lesser extent, Python) programming and slowly feeling my CS education slip away, I decided I wanted to broaden my horizons / general usefulness to the world and do something that feels more (to me) like I really have an influence over the machine. I chose to learn C and Unix programming since I feel like that is where many of the most interesting problems are. My end goal is to be able to do this professionally, if for no other reason than the fact that I have to spend 40-50 hours per week on work that pays the bills, so it may as well also be the type of coding I want to get better at. Of course, you don't get hired to do things you haven't dont before, so for now I am ramping up on my own. To this end, I started with K&R, which was a great resource in part due to the exercises spread throughout each chapter. After that I moved on to Computer Systems: A Programmer's Perspective, followed by ten chapters of Advanced Programming in the Unix Environment. When I am done with this book, I will read Unix Network Programming. What I'm missing in the Stevens books is the lack of programming problems; they mainly document functionality and provide examples, with a few end-of-chapter questions following. I feel that I would benefit much more from being challenged to use the knowledge in each chapter ala K&R. I could write some test program for each function, but this is a less desirable method as (1) I would probably be less motivated than if I were rising to some external challenge, and (2) I will naturally only think to use the function in the ways that have already occurred to me. So, I'd like to get some recommendations on how to practice. Obviously, my first choice would be to find some resource that has Unix programming challenges. I have also considered finding and attempting to contribute to some open source C project, but this is a bit daunting as there would be some overhead in learning to use the software, then learning the codebase. The only open-source C project I can think of that I use regularly is Python, and I'm not sure how easy that would be to get started on. That said, I'm open to all kinds of suggestions as there are likely things I haven't even thought of.

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  • Ubuntu hard disk problem

    - by Henadzy
    Hello! I have got the error with a hard disk on Ubuntu 9.10. It slows down my system, applications have not been responding for a long time. But when I mount and use filesystem which placed on this hard disk at other computer it works properly. disk: SAMSUNG HD161HJ (SATA) syslog: Apr 25 00:28:25 vare6gin kernel: [ 885.773839] ata3.00: exception Emask 0x1 SAct 0x1e SErr 0x0 action 0x6 frozen Apr 25 00:28:25 vare6gin kernel: [ 885.773845] ata3.00: Ata error. fis:0x21 Apr 25 00:28:25 vare6gin kernel: [ 885.773861] ata3.00: cmd 60/08:08:3f:00:ad/00:00:10:00:00/40 tag 1 ncq 4096 in Apr 25 00:28:25 vare6gin kernel: [ 885.773864] res 51/40:24:67:c8:91/40:00:05:00:00/40 Emask 0x9 (media error) Apr 25 00:28:25 vare6gin kernel: [ 885.773871] ata3.00: status: { DRDY ERR } Apr 25 00:28:25 vare6gin kernel: [ 885.773877] ata3.00: error: { UNC } Apr 25 00:28:25 vare6gin kernel: [ 885.773890] ata3.00: cmd 60/18:10:9f:6b:ed/00:00:0e:00:00/40 tag 2 ncq 12288 in Apr 25 00:28:25 vare6gin kernel: [ 885.773893] res 51/40:24:67:c8:91/40:00:05:00:00/40 Emask 0x9 (media error) Apr 25 00:28:25 vare6gin kernel: [ 885.773900] ata3.00: status: { DRDY ERR } Apr 25 00:28:25 vare6gin kernel: [ 885.773904] ata3.00: error: { UNC } Apr 25 00:28:25 vare6gin kernel: [ 885.773918] ata3.00: cmd 60/08:18:3f:5f:ed/00:00:0e:00:00/40 tag 3 ncq 4096 in Apr 25 00:28:25 vare6gin kernel: [ 885.773921] res 51/40:24:67:c8:91/40:00:05:00:00/40 Emask 0x9 (media error) Apr 25 00:28:25 vare6gin kernel: [ 885.773927] ata3.00: status: { DRDY ERR } Apr 25 00:28:25 vare6gin kernel: [ 885.773932] ata3.00: error: { UNC } Apr 25 00:28:25 vare6gin kernel: [ 885.773946] ata3.00: cmd 60/08:20:67:c8:91/00:00:05:00:00/40 tag 4 ncq 4096 in Apr 25 00:28:25 vare6gin kernel: [ 885.773948] res 51/40:24:67:c8:91/40:00:05:00:00/40 Emask 0x9 (media error) Apr 25 00:28:25 vare6gin kernel: [ 885.773955] ata3.00: status: { DRDY ERR } Apr 25 00:28:25 vare6gin kernel: [ 885.773960] ata3.00: error: { UNC } Apr 25 00:28:25 vare6gin kernel: [ 885.773970] ata3: hard resetting link Apr 25 00:28:25 vare6gin kernel: [ 885.773974] ata3: nv: skipping hardreset on occupied port Apr 25 00:28:25 vare6gin kernel: [ 886.240073] ata3: SATA link up 3.0 Gbps (SStatus 123 SControl 300) Apr 25 00:28:25 vare6gin kernel: [ 886.256277] ata3.00: configured for UDMA/133 Apr 25 00:28:25 vare6gin kernel: [ 886.256305] ata3: EH complete Apr 25 00:28:27 vare6gin kernel: [ 888.176088] ata3: EH in SWNCQ mode,QC:qc_active 0xF sactive 0xF Apr 25 00:28:27 vare6gin kernel: [ 888.176099] ata3: SWNCQ:qc_active 0xF defer_bits 0x0 last_issue_tag 0x3 Apr 25 00:28:27 vare6gin kernel: [ 888.176102] dhfis 0xF dmafis 0x1 sdbfis 0x0 Apr 25 00:28:27 vare6gin kernel: [ 888.176109] ata3: ATA_REG 0x51 ERR_REG 0x40 Apr 25 00:28:27 vare6gin kernel: [ 888.176113] ata3: tag : dhfis dmafis sdbfis sacitve Apr 25 00:28:27 vare6gin kernel: [ 888.176120] ata3: tag 0x0: 1 1 0 1 Apr 25 00:28:27 vare6gin kernel: [ 888.176126] ata3: tag 0x1: 1 0 0 1 Apr 25 00:28:27 vare6gin kernel: [ 888.176131] ata3: tag 0x2: 1 0 0 1 Apr 25 00:28:27 vare6gin kernel: [ 888.176136] ata3: tag 0x3: 1 0 0 1

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  • Easiest Way To Get Started In Dot Net

    - by Avery Payne
    Ok, so the initial search in StackOverflow shows nothing related for this question. So here it goes: Let's pretend for a moment that you're just getting started in a career in computer programming. Let's say that, for whatever reason, you decide to use the .Net framework as a basis for your programming. Let's also say that you've been exposed to some programming background, but not one in .Net, so it seems foreign to you at first. And lastly, you don't have the benefit of 25 years of exposure to the Win32 API, which explains why it seems so foreign to you when you start looking at it. So the questions are: What is a comprehensive overview of what .Net is? It appears to be a combination of a runtime environment, a set of languages, a common set of libraries, and perhaps a few other things...so it's about as clear as mud. Specifically, what are the key components to .Net? What is the easiest way to understand .Net programming with regard to available APIs? Which language would best suit beginning programming out of the "stock" languages that Microsoft has to offer? (C++, C#, VB, etc.) What are some differences between .Net programming and programming in a procedural language (aka Pascal, Modula, etc.) What are some differences between .Net programming and programming in a "traditional" object-oriented language? (aka Smalltalk, Java, Python, Ruby, etc.) As I currently understand it, the CLR provides a foundation for all of the other languages to run on. What are some of the inherent limitations of the CLR? Given the enormous amount of API to cover, would it even be worth learning a .Net language (using the Microsoft APIs) given that you would not have prior exposure to Win32 programming? Let's say you write a for-profit program with .Net. Can you resell the program without running afoul of licensing issues? Let's say you write a gratis (free) program with .Net. Can you offer the program to the public under a "free" license (GPL, BSD, Artistic, etc.) without running afoul of licensing issues? Thank you in advance for your patience.

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  • Would Ruby on Rails be appropriate for this Foreign Language project?

    - by Lynne Overesch-Maister
    I'm a Spanish professor & computer groupie. About 15 years ago, I authored in HyperCard a series of verb conjugation programs that are now completely out of date with respect to System OS X. I would like to redo these programs myself because I had a lot of fun doing them last time (mostly I coded while my son played in Leaps and Bounds, you know, one of those places where parents take their kids & let them run wild through the tubes...). Colleagues have mentioned using Flash, Director, and various other solutions, but I saw a presentation on RoR at our SIDLIT conference today, and was inspired. I will be parsing and comparing strings (and there are other features on top of that, but that is the main one), "adding" strings relationally indexed in some kind of database(s). It will also have to handle various foreign characters (accents, upside down question marks, etc.). On top of the main process of the program, it will have to provide a practice vs. test mode, keep track of specific answers as well as totals right/wrong, and print a report. Would this be either easier and/or more efficiently done in RoR than in other languages. I am pretty sure that it will work on a Microsoft server, right? Because I think that is where most of our stuff is. I would be programming either on a Mac or a PC, whichever you think is easier. So, in summary, is RoR the way for me to go with this project? If I have some (little) experience programming in Hypercard and C, should I be able to pick RoR up fairly quickly? What things will I need to start (I already saw something called Redhills foreign key migration plugin, which I assume would be beneficial)? I still have my old scripts from hypercard, however what I would really like to do is to combine all six of my former tense-specific programs into one larger program. I figure that it wouldn't be too hard to reference the individual tenses in some way--could that be a class? Many thanks for any help you can give me on this forum.

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  • Good Secure Backups Developers at Home

    - by slashmais
    What is a good, secure, method to do backups, for programmers who do research & development at home and cannot afford to lose any work? Conditions: The backups must ALWAYS be within reasonably easy reach. Internet connection cannot be guaranteed to be always available. The solution must be either FREE or priced within reason, and subject to 2 above. Status Report This is for now only considering free options. The following open-source projects are suggested in the answers (here & elsewhere): BackupPC is a high-performance, enterprise-grade system for backing up Linux, WinXX and MacOSX PCs and laptops to a server's disk. Storebackup is a backup utility that stores files on other disks. mybackware: These scripts were developed to create SQL dump files for basic disaster recovery of small MySQL installations. Bacula is [...] to manage backup, recovery, and verification of computer data across a network of computers of different kinds. In technical terms, it is a network based backup program. AutoDL 2 and Sec-Bk: AutoDL 2 is a scalable transport independant automated file transfer system. It is suitable for uploading files from a staging server to every server on a production server farm [...] Sec-Bk is a set of simple utilities to securely back up files to a remote location, even a public storage location. rsnapshot is a filesystem snapshot utility for making backups of local and remote systems. rbme: Using rsync for backups [...] you get perpetual incremental backups that appear as full backups (for each day) and thus allow easy restore or further copying to tape etc. Duplicity backs directories by producing encrypted tar-format volumes and uploading them to a remote or local file server. [...] uses librsync, [for] incremental archives Other Possibilities: Using a Distributed Version Control System (DVCS) such as Git(/Easy Git), Bazaar, Mercurial answers the need to have the backup available locally. Use free online storage space as a remote backup, e.g.: compress your work/backup directory and mail it to your gmail account. Strategies See crazyscot's answer

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  • Miller-rabin exception number?

    - by nightcracker
    Hey everyone. This question is about the number 169716931325235658326303. According to http://www.alpertron.com.ar/ECM.HTM it is prime. According to my miller-rabin implementation in python with 7 repetitions is is composite. With 50 repetitions it is still composite. With 5000 repetitions it is STILL composite. I thought, this might be a problem of my implementation. So I tried GNU MP bignum library, which has a miller-rabin primality test built-in. I tested with 1000000 repetitions. Still composite. This is my implementation of the miller-rabin primality test: def isprime(n, precision=7): if n == 1 or n % 2 == 0: return False elif n < 1: raise ValueError("Out of bounds, first argument must be > 0") d = n - 1 s = 0 while d % 2 == 0: d //= 2 s += 1 for repeat in range(precision): a = random.randrange(2, n - 2) x = pow(a, d, n) if x == 1 or x == n - 1: continue for r in range(s - 1): x = pow(x, 2, n) if x == 1: return False if x == n - 1: break else: return False return True And the code for the GMP test: #include <gmp.h> #include <stdio.h> int main(int argc, char* argv[]) { mpz_t test; mpz_init_set_str(test, "169716931325235658326303", 10); printf("%d\n", mpz_probab_prime_p(test, 1000000)); mpz_clear(test); return 0; } As far as I know there are no "exceptions" (which return false positives for any amount of repetitions) to the miller-rabin primality test. Have I stumpled upon one? Is my computer broken? Is the Elliptic Curve Method wrong? What is happening here? EDIT I found the issue, which is http://www.alpertron.com.ar/ECM.HTM. I trusted this applet, I'll contact the author his applet's implementation of the ECM is faulty for this number. Thanks. EDIT2 Hah, the shame! In the end it was something that went wrong with copy/pasting on my side. NOR the applet NOR the miller-rabin algorithm NOR my implementation NOR gmp's implementation of it is wrong, the only thing that's wrong is me. I'm sorry.

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  • Really "wow" them in the interview

    - by Juliet
    Let me put it to you this way: I'm a top-notch programmer, but a notoriously bad interviewee. I've flunked 3 interviews consecutively because I get so nervous that my voice tightens at least 2 octaves higher and I start visibly shaking -- mind you, I can handle whatever technical questions the interviewer throws at me in that state, but I think it looks bad to come off as a quivering, squeaky-voiced young woman during a job interview. I've just got the personality type of a shy computer programmer. No matter how technical I am, I'm going to get passed up in favor of a smooth talker. I have another interview coming up shortly, and I want to really impress the company. Here are my trouble spots: What can I do to be less nervous during my interview? I always get really excited when I hear I have a face-to-face interview, but get more and more anxious as D-Day the interview approaches. My employers wants me to explain what I used to do at my prior employment. I'm a very chatty person and tend to talk/squeak for 10 minutes at a time. How long or short should I time my answers? On that note, when I'm explaining what I did at prior jobs, what exactly is my interviewer looking for? At some point, my interviewer will ask "do you have any questions for me while you're here?" I should, but what kinds of questions should I ask to show that I'm interested in being employed? My interviewer always asks why I'm looking for a new job. The real reason is that my present salary is $27K/yr [Edit to add: and I've yet to get a raise since I started], and I want to make more money -- otherwise the work environment is fine. How do I sugarcoat "I want to make more money" into something that sounds nicer? I have only one prior programmer job, and I've worked there for 18 months, but I have the skill of someone with 4 to 6 years of experience. What can I say to compete against applicants with more work experience? I took a low-paying $27K/yr programming job just to get my foot in IT, and I've been trying to leverage that job as a stepping stone to better opportunities. I get interviews because I consistently out-score senior-level developers in aptitude tests, and my desired salary range is right in the ballpark of what most companies want to offer. Unfortunately, while I've been a programming as a hobby for 10 years and I'm geared to graduate with my BA in Comp Sci in May '09, employers see me as a junior-level programmer with no degree. I want to prove them wrong and get a job that matches my skill level. I'd appreciate any advice anyone has to offer, especially if they can help me get a better job in the process.

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  • Beautifulsoup recursive attribute

    - by Marcos Placona
    Hi, trying to parse an XML with Beautifulsoup, but hit a brick wall when trying to use the "recursive" attribute with findall() I have a pretty odd xml format shown below: <?xml version="1.0"?> <catalog> <book id="bk101"> <author>Gambardella, Matthew</author> <title>XML Developer's Guide</title> <genre>Computer</genre> <price>44.95</price> <publish_date>2000-10-01</publish_date> <description>An in-depth look at creating applications with XML.</description> <catalog>true</catalog> </book> <book id="bk102"> <author>Ralls, Kim</author> <title>Midnight Rain</title> <genre>Fantasy</genre> <price>5.95</price> <publish_date>2000-12-16</publish_date> <description>A former architect battles corporate zombies, an evil sorceress, and her own childhood to become queen of the world.</description> <catalog>false</catalog> </book> </catalog> As you can see, the catalog tag repeats inside the book tag, which causes an error when I try to to something like: from BeautifulSoup import BeautifulStoneSoup as BSS catalog = "catalog.xml" def open_rss(): f = open(catalog, 'r') return f.read() def rss_parser(): rss_contents = open_rss() soup = BSS(rss_contents) items = soup.findAll('catalog', recursive=False) for item in items: print item.title.string rss_parser() As you will see, on my soup.findAll I've added recursive=false, which in theory would make it no recurse through the item found, but skip to the next one. This doesn't seem to work, as I always get the following error: File "catalog.py", line 17, in rss_parser print item.title.string AttributeError: 'NoneType' object has no attribute 'string' I'm sure I'm doing something stupid here, and would appreciate if someone could give me some help on how to solve this problem. Changing the HTML structure is not an option, this this code needs to perform well as it will potentially parse a large XML file. Thanks in advance, Marcos

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  • Publishing WCF .NET 3.5 to IIS 6 (Windows Server 2003)

    - by Adam
    I've been developing a WCF web service using .NET 3.5 with IIS7 and it works perfectly on my local computer. I tried publishing it to a server running IIS 6 and even though I can view the WSDL in my browser, the client application doesn't seem to be connecting to it correctly. I launched a packet sniffing app (Charles Proxy) and the response for the first message comes back to the client empty (0 bytes). Every message after the first one times out. The WCF service is part of a larger application that uses ASP .NET 3.5. That application has been working fine on IIS 6 for awhile now so I think it's something specific to WCF. I also tried throwing an exception in the SVC file to see if it made it that far and the exception never got thrown so I have a feeling it's something more low level that's not working. Any thoughts? Is there anything I need to install on the IIS5 server? If so how am I still able to view the WSDL in my browser? The service is being consumed via an SVC file using basicHttpBinding Here's the meat of the Web.Config (let me know if you need any other part of it): <system.net> <defaultProxy> <proxy usesystemdefault="False" proxyaddress="http://127.0.0.1:80" bypassonlocal="True"/> </defaultProxy> </system.net> ... <system.serviceModel> <services> <service name="Nexternal.Service.XMLTools.VNService" behaviorConfiguration="VNServiceBehavior"> <!--The first endpoint would be picked up from the confirg this shows how the config can be overriden with the service host--> <endpoint address="" binding="basicHttpBinding" contract="Nexternal.Service.XMLTools.IVNService" /> <endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange" name="mexHttpBinding" /> </service> </services> <behaviors> <serviceBehaviors> <behavior name="VNServiceBehavior"> <serviceMetadata httpGetEnabled="true" /> <serviceDebug includeExceptionDetailInFaults="true" /> </behavior> </serviceBehaviors> </behaviors> <serviceHostingEnvironment aspNetCompatibilityEnabled="true" /> </system.serviceModel>

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  • java.lang.ClassNotFoundException: org.apache.struts2.dispatcher.FilterDispatcher

    - by user714698
    log when start the tomcat Apr 28, 2011 10:52:57 AM org.apache.catalina.core.AprLifecycleListener init INFO: The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: D:\software\jdk1.5.0_06\bin;.;C:\WINDOWS\system32;C:\WINDOWS;D:/software/jdk1.5.0_06/bin/../jre/bin/client;D:/software/jdk1.5.0_06/bin/../jre/bin;C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\System32\Wbem;C:\Program Files\TortoiseSVN\bin.;D:\software\jdk1.5.0_06\bin;D:\software\Ant 1.7\bin;D:\software\Axis2-1.5.4\axis2-1.5.4-bin\axis2-1.5.4\bin;C:\Program Files\IDM Computer Solutions\UltraEdit\ Apr 28, 2011 10:52:58 AM org.apache.tomcat.util.digester.SetPropertiesRule begin WARNING: [SetPropertiesRule]{Server/Service/Engine/Host/Context} Setting property 'source' to 'org.eclipse.jst.jee.server:StrutsHelloWorld' did not find a matching property. Apr 28, 2011 10:52:58 AM org.apache.tomcat.util.digester.SetPropertiesRule begin WARNING: [SetPropertiesRule]{Server/Service/Engine/Host/Context} Setting property 'source' to 'org.eclipse.jst.jee.server:StrutsHelloWorld1' did not find a matching property. Apr 28, 2011 10:53:00 AM org.apache.coyote.http11.Http11Protocol init INFO: Initializing Coyote HTTP/1.1 on http-8080 Apr 28, 2011 10:53:00 AM org.apache.catalina.startup.Catalina load INFO: Initialization processed in 3657 ms Apr 28, 2011 10:53:00 AM org.apache.catalina.core.StandardService start INFO: Starting service Catalina Apr 28, 2011 10:53:00 AM org.apache.catalina.core.StandardEngine start INFO: Starting Servlet Engine: Apache Tomcat/6.0.32 Apr 28, 2011 10:53:01 AM org.apache.catalina.core.StandardContext filterStart SEVERE: Exception starting filter struts2 java.lang.ClassNotFoundException: org.apache.struts2.dispatcher.FilterDispatcher at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1680) at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1526) at org.apache.catalina.core.ApplicationFilterConfig.getFilter(ApplicationFilterConfig.java:269) at org.apache.catalina.core.ApplicationFilterConfig.setFilterDef(ApplicationFilterConfig.java:422) at org.apache.catalina.core.ApplicationFilterConfig.<init>(ApplicationFilterConfig.java:115) at org.apache.catalina.core.StandardContext.filterStart(StandardContext.java:4071) at org.apache.catalina.core.StandardContext.start(StandardContext.java:4725) at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1053) at org.apache.catalina.core.StandardHost.start(StandardHost.java:840) at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1053) at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:463) at org.apache.catalina.core.StandardService.start(StandardService.java:525) at org.apache.catalina.core.StandardServer.start(StandardServer.java:754) at org.apache.catalina.startup.Catalina.start(Catalina.java:595) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:585) at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:289) at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:414) Apr 28, 2011 10:53:01 AM org.apache.catalina.core.StandardContext start SEVERE: Error filterStart Apr 28, 2011 10:53:01 AM org.apache.catalina.core.StandardContext start SEVERE: Context [/StrutsHelloWorld1] startup failed due to previous errors log4j:WARN No appenders could be found for logger (com.opensymphony.xwork2.config.providers.XmlConfigurationProvider). log4j:WARN Please initialize the log4j system properly. Apr 28, 2011 10:53:05 AM org.apache.coyote.http11.Http11Protocol start INFO: Starting Coyote HTTP/1.1 on http-8080 Apr 28, 2011 10:53:05 AM org.apache.jk.common.ChannelSocket init INFO: JK: ajp13 listening on /0.0.0.0:8009 Apr 28, 2011 10:53:05 AM org.apache.jk.server.JkMain start INFO: Jk running ID=0 time=0/46 config=null Apr 28, 2011 10:53:05 AM org.apache.catalina.startup.Catalina start INFO: Server startup in 4951 ms

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  • CSS selectors : should I make my CSS easier to read or optimise the speed

    - by Laurent Bourgault-Roy
    As I was working on a small website, I decided to use the PageSpeed extension to check if their was some improvement I could do to make the site load faster. However I was quite surprise when it told me that my use of CSS selector was "inefficient". I was always told that you should keep the usage of the class attribute in the HTML to a minimum, but if I understand correctly what PageSpeed tell me, it's much more efficient for the browser to match directly against a class name. It make sense to me, but it also mean that I need to put more CSS classes in my HTML. It make my .css file harder to read. I usually tend to mark my CSS like this : #mainContent p.productDescription em.priceTag { ... } Which make it easy to read : I know this will affect the main content and that it affect something in a paragraph tag (so I wont start to put all sort of layout code in it) that describe a product and its something that need emphasis. However it seem I should rewrite it as .priceTag { ... } Which remove all context information about the style. And if I want to use differently formatted price tag (for example, one in a list on the sidebar and one in a paragraph), I need to use something like that .paragraphPriceTag { ... } .listPriceTag { ... } Which really annoy me since I seem to duplicate the semantic of the HTML in my classes. And that mean I can't put common style in an unqualified .priceTag { ... } and thus I need to replicate the style in both CSS rule, making it harder to make change. (Altough for that I could use multiple class selector, but IE6 dont support them) I believe making code harder to read for the sake of speed has never been really considered a very good practice . Except where it is critical, of course. This is why people use PHP/Ruby/C# etc. instead of C/assembly to code their site. It's easier to write and debug. So I was wondering if I should stick with few CSS classes and complex selector or if I should go the optimisation route and remove my fancy CSS selectors for the sake of speed? Does PageSpeed make over the top recommandation? On most modern computer, will it even make a difference?

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  • Is this slow WPF TextBlock performance expected?

    - by Ben Schoepke
    Hi, I am doing some benchmarking to determine if I can use WPF for a new product. However, early performance results are disappointing. I made a quick app that uses data binding to display a bunch of random text inside of a list box every 100 ms and it was eating up ~15% CPU. So I made another quick app that skipped the data binding/data template scheme and does nothing but update 10 TextBlocks that are inside of a ListBox every 100 ms (the actual product wouldn't require 100 ms updates, more like 500 ms max, but this is a stress test). I'm still seeing ~10-15% CPU usage. Why is this so high? Is it because of all the garbage strings? Here's the XAML: <Grid> <ListBox x:Name="numericsListBox"> <ListBox.Resources> <Style TargetType="TextBlock"> <Setter Property="FontSize" Value="48"/> <Setter Property="Width" Value="300"/> </Style> </ListBox.Resources> <TextBlock/> <TextBlock/> <TextBlock/> <TextBlock/> <TextBlock/> <TextBlock/> <TextBlock/> <TextBlock/> <TextBlock/> <TextBlock/> </ListBox> </Grid> Here's the code behind: public partial class Window1 : Window { private int _count = 0; public Window1() { InitializeComponent(); } private void OnLoad(object sender, RoutedEventArgs e) { var t = new DispatcherTimer(TimeSpan.FromSeconds(0.1), DispatcherPriority.Normal, UpdateNumerics, Dispatcher); t.Start(); } private void UpdateNumerics(object sender, EventArgs e) { ++_count; foreach (object textBlock in numericsListBox.Items) { var t = textBlock as TextBlock; if (t != null) t.Text = _count.ToString(); } } } Any ideas for a better way to quickly render text? My computer: XP SP3, 2.26 GHz Core 2 Duo, 4 GB RAM, Intel 4500 HD integrated graphics. And that is an order of magnitude beefier than the hardware I'd need to develop for in the real product.

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  • WMI: Editing the Registry Remotely

    - by Quanta
    I'm trying to use the following code (poorly written, but it's just a proof of concept) to edit the registry of a computer on a domain. I have a domain account, and I've verified that the domain admin group is present in the local admin group on the machines I'm attempting to affect. I've connected to these other machines to perform other administrative type tasks, so I'm sure that I have administrative privileges on these hosts. All of StdRegProv's "get" methods work fine (http://msdn.microsoft.com/en-us/library/aa393664%28VS.85%29.aspx) but the "set" or "create" methods as well as check access all return "5" which is "Error_Access_Denied" according to winerror.h. So there's the problem: why do I get access denied when attempting to modify the registry? If anyone can help me figure this out, you'd have my utmost appreciation! I almost forgot, when I fire up Visual Studio in admin mode on my local machine and run the code against the local machine, it works flawlessly. If I don't start in admin mode on the local machine, the code fails, so I suspect there's a UAC problem maybe? using System; using System.Management; public class EditRemoteRegistry { public static void Main(string[] args) { ConnectionOptions options = new ConnectionOptions(); options.EnablePrivileges = true; options.Impersonation = ImpersonationLevel.Impersonate; options.Password = "password goes here"; //options.Authority = "my company's domain"; //options.Username = "Admin username"; ManagementScope scope = new ManagementScope("\\\\arbitraryhost\\root\\default", options); scope.Connect(); ManagementClass mc = new ManagementClass("StdRegProv"); ManagementBaseObject inParams = mc.GetMethodParameters("CreateKey"); inParams["hDefKey"] = (UInt32)2147483650; inParams["sSubKeyName"] = "Software\\Test"; ManagementBaseObject outParams = mc.InvokeMethod("CreateKey", inParams, null); //Should return a 0, but returns a 5, "Error_Access_Denied" Console.WriteLine("CreateKey Method returned " + outParams["returnValue"]); //This chunk works fine ManagementBaseObject inParams5 = mc.GetMethodParameters("GetDWORDValue"); inParams5["hDefKey"] = 2147483650; inParams5["sSubKeyName"] = "Software\\Test"; inParams5["sValueName"] = "testDWORDvalue"; ManagementBaseObject outParams5 = mc.InvokeMethod("GetDWORDValue", inParams5, null); Console.WriteLine("GetDWORDValue returned " + (UInt32)outParams5["returnValue"] + " "); Console.WriteLine((UInt32)outParams5["uValue"]); ManagementBaseObject inParams6 = mc.GetMethodParameters("SetStringValue"); inParams6["hDefKey"] = 2147483650; inParams6["sSubKeyName"] = "Software\\Test"; inParams6["sValueName"] = "TestStringValue"; inParams6["sValue"] = "Hello World!"; ManagementBaseObject outParams6 = mc.InvokeMethod("SetStringValue", inParams6, null); //Should return a 0, but returns a 5, "Error_Access_Denied" Console.WriteLine("SetStringValue returned " + outParams6["returnValue"]); Console.ReadKey(); } }

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  • compiling opencv 2.4 on a 64 bit mac in Xcode

    - by Walt
    I have an opencv project that I've been developing under ubuntu 12.04, on a parellels VM on a mac which has an x86_64 architecture. There have been many screen switching performance issues that I believe are due to the VM, where linux video modes flip around for a couple seconds while camera access is made by the opencv application. I decided to moved the project into Xcode on the mac side of the computer to continue the opencv development. However, I'm not that familiar with xcode and am having trouble getting the project to build correctly there. I have xcode installed. I downloaded and decompressed the latest version of opencv on the mac, and ran: ~/src/opencv/build/cmake-gui -G Xcode .. per the instructions from willowgarage and various other locations. This appeared to work fine (however I'm wondering now if I'm missing an architecture setting in here, although it is 64-bit intel in Xcode). I then setup an xcode project with the source files from the linux project and changed the include directories to use /opt/local/include/... rather than the /usr/local/include/... I switched xcode to use the LLVM GCC compiler in the build settings for the project then set the Apple LLVM Dialog for C++ to Language Dialect to GNU++11 (which seems possibly inconsistant with the line above) I'm not using a makefile in xcode, (that I'm aware of - it has its own project file...) I was also running into a linker issue that looked like they may be resolved with the addition of this linker flag: -lopencv_video based on a similar posting here: other thread however in that case the person was using a Makefile in their project. I've tried adding this linker flag under "Other Linker Flags" in xcode build settings but still get build errors. I think I may have two issues here, one with the architecture settings when building the opencv libraries with Cmake, and one with the linker flag settings in my project. Currently the build error list looks like this: Undefined symbols for architecture x86_64: "cv::_InputArray::_InputArray(cv::Mat const&)", referenced from: _main in main.o "cv::_OutputArray::_OutputArray(cv::Mat&)", referenced from: _main in main.o "cv::Mat::deallocate()", referenced from: cv::Mat::release() in main.o "cv::Mat::copySize(cv::Mat const&)", referenced from: cv::Mat::Mat(cv::Mat const&)in main.o cv::Mat::operator=(cv::Mat const&)in main.o "cv::Mat::Mat(_IplImage const*, bool)", referenced from: _main in main.o "cv::imread(std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, int)", referenced from: _main in main.o ---SNIP--- ld: symbol(s) not found for architecture x86_64 collect2: ld returned 1 exit status Can anyone provide some guidance on what to try next? Thanks, Walt

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  • agent-based simulation: performance issue: Python vs NetLogo & Repast

    - by max
    I'm replicating a small piece of Sugarscape agent simulation model in Python 3. I found the performance of my code is ~3 times slower than that of NetLogo. Is it likely the problem with my code, or can it be the inherent limitation of Python? Obviously, this is just a fragment of the code, but that's where Python spends two-thirds of the run-time. I hope if I wrote something really inefficient it might show up in this fragment: UP = (0, -1) RIGHT = (1, 0) DOWN = (0, 1) LEFT = (-1, 0) all_directions = [UP, DOWN, RIGHT, LEFT] # point is just a tuple (x, y) def look_around(self): max_sugar_point = self.point max_sugar = self.world.sugar_map[self.point].level min_range = 0 random.shuffle(self.all_directions) for r in range(1, self.vision+1): for d in self.all_directions: p = ((self.point[0] + r * d[0]) % self.world.surface.length, (self.point[1] + r * d[1]) % self.world.surface.height) if self.world.occupied(p): # checks if p is in a lookup table (dict) continue if self.world.sugar_map[p].level > max_sugar: max_sugar = self.world.sugar_map[p].level max_sugar_point = p if max_sugar_point is not self.point: self.move(max_sugar_point) Roughly equivalent code in NetLogo (this fragment does a bit more than the Python function above): ; -- The SugarScape growth and motion procedures. -- to M ; Motion rule (page 25) locals [ps p v d] set ps (patches at-points neighborhood) with [count turtles-here = 0] if (count ps > 0) [ set v psugar-of max-one-of ps [psugar] ; v is max sugar w/in vision set ps ps with [psugar = v] ; ps is legal sites w/ v sugar set d distance min-one-of ps [distance myself] ; d is min dist from me to ps agents set p random-one-of ps with [distance myself = d] ; p is one of the min dist patches if (psugar >= v and includeMyPatch?) [set p patch-here] setxy pxcor-of p pycor-of p ; jump to p set sugar sugar + psugar-of p ; consume its sugar ask p [setpsugar 0] ; .. setting its sugar to 0 ] set sugar sugar - metabolism ; eat sugar (metabolism) set age age + 1 end On my computer, the Python code takes 15.5 sec to run 1000 steps; on the same laptop, the NetLogo simulation running in Java inside the browser finishes 1000 steps in less than 6 sec. EDIT: Just checked Repast, using Java implementation. And it's also about the same as NetLogo at 5.4 sec. Recent comparisons between Java and Python suggest no advantage to Java, so I guess it's just my code that's to blame? EDIT: I understand MASON is supposed to be even faster than Repast, and yet it still runs Java in the end.

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  • Revision control for writing programming lessons

    - by Dietrich Epp
    I'd like to write a series programming lessons that guide programmers to build a certain kind of program. After each lesson, I'd like to provide sample code that implements what that lesson covered, and the next lesson would use that code as a starting point. Right now I'm using Git to keep track of the code from lesson to lesson. Each lesson has its own branch. lesson1: A--B--C \ lesson2: D--E--F \ lesson3: G--H--I However, suppose that now I want to make it easier on the Windows programmers using my lessons, so I add a Visual Studio project to lesson 1 and then merge it into lessons 2 and 3. lesson1: A--B--C--------------J \ \ lesson2: D--E--F--------K \ \ lesson3: G--H--I--L And then someone points out a bug in lesson 2 that causes crashes on certain systems. (This diagram is where I am right now, and I'm having doubts about continuing along this path.) lesson1: A--B--C--------------J \ \ lesson2: D--E--F--------K--M \ \ \ lesson3: G--H--I--L--N Here are the problems I imagine having: If I had many lessons, and I fix something in lesson 1, am I going to have to spend fifteen minutes or more just merging that one simple change? I know I'll probably have to test all of those lessons again, but I can put that off. When I make a bunch of changes to various lessons on one computer, how do I pull all of the branches at the same time? If I decide to publish these lessons, I'd like a way to tag all of the branches to correspond with what I publish. I figure I'll just need to tag each branch separately, but it would be nice if there were a better way. When I look at the history, I imagine becoming terribly confused about what I've done. Compare the above diagram to a hypothetical diagram below, where I use rebase instead of merge (and rebase has its own problems): lesson1: A--B--C--J \ lesson2: D2--E2--F2--M \ lesson3: G2--H2--I2 Do any of you have experience working with a project like this? Should I consider using a different VCS, such as Darcs? (Note: it would be a real pain to use centralized VCS, so don't suggest one of those unless the benefits are clear.) Should I consider writing plugins or extra tools for a VCS (such as a "meta tag" which tags several branches)?

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  • Linked List Design

    - by Jim Scott
    The other day in a local .NET group I attend the following question came up: "Is it a valid interview question to ask about Linked Lists when hiring someone for a .NET development position?" Not having a computer sciense degree and being a self taught developer my response was that I did not feel it was appropriate as I in 5 years of developer with .NET had never been exposed to linked lists and did not hear any compeling reason for a use for one. However the person commented that it is a very common interview question so I decided when I left that I would do some reasearch on linked lists and see what I might be missing. I have read a number of posts on stack overflow and various google searches and decided the best way to learn about them was to write my own .NET classes to see how they worked from the inside out. Here is my class structure Single Linked List Constructor public SingleLinkedList(object value) Public Properties public bool IsTail public bool IsHead public object Value public int Index public int Count private fields not exposed to a property private SingleNode firstNode; private SingleNode lastNode; private SingleNode currentNode; Methods public void MoveToFirst() public void MoveToLast() public void Next() public void MoveTo(int index) public void Add(object value) public void InsertAt(int index, object value) public void Remove(object value) public void RemoveAt(int index) Questions I have: What are typical methods you would expect in a linked list? What is typical behaviour when adding new records? For example if I have 4 nodes and I am currently positioned in the second node and perform Add() should it be added after or before the current node? Or should it be added to the end of the list? Some of the designs I have seen explaining things seem to expose outside of the LinkedList class the Node object. In my design you simply add, get, remove values and know nothing about any node object. Should the Head and Tail be placeholder objects that are only used to define the head/tail of the list? I require my Linked List be instantiated with a value which creates the first node of the list which is essentially the head and tail of the list. Would you change that ? What should the rules be when it comes to removing nodes. Should someone be able to remove all nodes? Here is my Double Linked List Constructor public DoubleLinkedList(object value) Properties public bool IsHead public bool IsTail public object Value public int Index public int Count Private fields not exposed via property private DoubleNode currentNode; Methods public void AddFirst(object value) public void AddLast(object value) public void AddBefore(object existingValue, object value) public void AddAfter(object existingValue, object value) public void Add(int index, object value) public void Add(object value) public void Remove(int index) public void Next() public void Previous() public void MoveTo(int index)

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  • FASM vc MASM trasnlation problem in mov si, offset msg

    - by Ruben Trancoso
    hi folks, just did my first test with MASM and FASM with the same code (almos) and I falled in trouble. The only difference is that to produce just the 104 bytes I need to write to MBR in FASM I put org 7c00h and in MASM 0h. The problem is on the mov si, offset msg that in the first case transletes it to 44 7C (7c44h) and with masm translates to 44 00 (0044h)! but just when I change org 7c00h to org 0h in MASM. Otherwise it will produce the entire segment from 0 to 7dff. how do I solve it? or in short, how to make MASM produce a binary that begins at 7c00h as it first byte and subsequent jumps remain relative to 7c00h? .model TINY .code org 7c00h ; Boot entry point. Address 07c0:0000 on the computer memory xor ax, ax ; Zero out ax mov ds, ax ; Set data segment to base of RAM jmp start ; Jump to the first byte after DOS boot record data ; ---------------------------------------------------------------------- ; DOS boot record data ; ---------------------------------------------------------------------- brINT13Flag db 90h ; 0002h - 0EH for INT13 AH=42 READ brOEM db 'MSDOS5.0' ; 0003h - OEM name & DOS version (8 chars) brBPS dw 512 ; 000Bh - Bytes/sector brSPC db 1 ; 000Dh - Sectors/cluster brResCount dw 1 ; 000Eh - Reserved (boot) sectors brFATs db 2 ; 0010h - FAT copies brRootEntries dw 0E0h ; 0011h - Root directory entries brSectorCount dw 2880 ; 0013h - Sectors in volume, < 32MB brMedia db 240 ; 0015h - Media descriptor brSPF dw 9 ; 0016h - Sectors per FAT brSPH dw 18 ; 0018h - Sectors per track brHPC dw 2 ; 001Ah - Number of Heads brHidden dd 0 ; 001Ch - Hidden sectors brSectors dd 0 ; 0020h - Total number of sectors db 0 ; 0024h - Physical drive no. db 0 ; 0025h - Reserved (FAT32) db 29h ; 0026h - Extended boot record sig brSerialNum dd 404418EAh ; 0027h - Volume serial number (random) brLabel db 'OSAdventure' ; 002Bh - Volume label (11 chars) brFSID db 'FAT12 ' ; 0036h - File System ID (8 chars) ;------------------------------------------------------------------------ ; Boot code ; ---------------------------------------------------------------------- start: mov si, offset msg call showmsg hang: jmp hang msg db 'Loading...',0 showmsg: lodsb cmp al, 0 jz showmsgd push si mov bx, 0007 mov ah, 0eh int 10h pop si jmp showmsg showmsgd: retn ; ---------------------------------------------------------------------- ; Boot record signature ; ---------------------------------------------------------------------- dw 0AA55h ; Boot record signature END

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  • .NET Application broken on one PC, unhandleable exception

    - by Bobby
    Hello people. I have a .NET 2.0 application with nothing fancy in it. It worked until yesterday on every PC I installed or copied it to, no matter if 2.0, 3.0, 3.5 or 3.5 SP1 was installed, no matter if it was Win2000, XP or even Win7 (in total 100+ machines). Yesterday I did my normal installation procedure and wanted to start it one time to check if everything is working...and it wasn't. The program crashed hard leaving me with the uninformative "Do you wanna report this error?" dialog. The problem is an exception in the Main(String[] args) routine of my application. The event viewer is showing the following entry: Event Type: ErrorEvent Source: .NET Runtime 2.0 Error Reporting Event Category: None Event ID: 5000 Date: 05/05/2010 Time: 16:09:09 User: N/A Computer: myClientPC Description: EventType clr20r3, P1 apomenu.exe, P2 1.4.90.53, P3 4bdedea4, P4 system.configuration, P5 2.0.0.0, P6 4889de74, P7 1a6, P8 136, P9 ioibmurhynrxkw0zxkyrvfn0boyyufow, P10 NIL. Well...great information. After a lot of searching I finally was able to get further information about this exception (by adding a handler for UnhandledExceptions directly in My.MyApplication.New(), Application.Designer.vb): System.Configuration.ConfigurationErrorsException Configuration system failed to initialize at System.Configuration.ClientConfigurationSystem.EnsureInit(String configKey) at System.Configuration.ClientConfigurationSystem.PrepareClientConfigSystem(String sectionName) at System.Configuration.ClientConfigurationSystem.System.Configuration.Internal.IInternalConfigSystem.GetSection(String sectionName) at System.Configuration.ConfigurationManager.GetSection(String sectionName) at System.Configuration.PrivilegedConfigurationManager.GetSection(String sectionName) at System.Net.Configuration.SettingsSectionInternal.get_Section() at System.Net.Sockets.Socket.InitializeSockets() at System.Net.Sockets.Socket.get_SupportsIPv4() at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.get_HostName() at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.RegisterChannel(Boolean SecureChannel) at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.Run(String[] commandLine) at MyAppNameHere.My.MyApplication.Main(String[] Args) in 17d14f5c-a337-4978-8281-53493378c1071.vb:Line 81. And at this point I'm stuck...I'm out of ideas. I'm not using any kind of configuration system from the framework (no reference to System.Configuration, and there never was a MyAppnameHere.exe.config generated or distributed, nor have I seen this error before). I also found a bug report at Microsoft (Google Cache) about this bug (in another context, though). But as it seems, they won't even look at it. Every help is greatly appreciated! Edit: I'm using Visual Studio 2008 Prof.. Crash happens in Release- and Debug-Build on the client machine. Debugging the application directly on this machine is out of question I fear, 300+ Miles and they only have two computers to work with.

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