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  • How di I fix this Synaptic manager error

    - by mick
    Synaptic manager is giving me the following error: Failed to fetch cdrom://Ubuntu 11.04 _Natty Narwhal_ - Release i386 (20110427.1)/kubuntu/dists/natty/main/binary-i386/Packages Please use apt-cdrom to make this CD-ROM recognised by APT. apt-get update cannot be used to add new CD-ROMs Failed to fetch cdrom://Ubuntu 11.04 _Natty Narwhal_ - Release i386 (20110427.1)/kubuntu/dists/natty/restricted/binary-i386/Packages Please use apt- cdrom to make this CD-ROM recognised by APT. apt-get update cannot be used to add new CD-ROMs Failed to fetch cdrom://Ubuntu 11.04 _Natty Narwhal_ - Release i386 (20110427.1)/xubuntu/dists/natty/main/binary-i386/Packages Please use apt-cdrom to make this CD-ROM recognised by APT. apt-get update cannot be used to add new CD-ROMs Failed to fetch cdrom://Ubuntu 11.04 _Natty Narwhal_ - Release i386 (20110427.1)/xubuntu/dists/natty/restricted/binary-i386/Packages Please use apt-cdrom to make this CD-ROM recognised by APT. apt-get update cannot be used to add new CD-ROMs

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  • How can I check if a binary string is UTF-8 in mysql?

    - by Piotr Czapla
    I've found a Perl regexp that can check if a string is UTF-8 (the regexp is from w3c site). $field =~ m/\A( [\x09\x0A\x0D\x20-\x7E] # ASCII | [\xC2-\xDF][\x80-\xBF] # non-overlong 2-byte | \xE0[\xA0-\xBF][\x80-\xBF] # excluding overlongs | [\xE1-\xEC\xEE\xEF][\x80-\xBF]{2} # straight 3-byte | \xED[\x80-\x9F][\x80-\xBF] # excluding surrogates | \xF0[\x90-\xBF][\x80-\xBF]{2} # planes 1-3 | [\xF1-\xF3][\x80-\xBF]{3} # planes 4-15 | \xF4[\x80-\x8F][\x80-\xBF]{2} # plane 16 )*\z/x; But I'm not sure how to port it to MySQL as it seems that MySQL don't support hex representation of characters see this question. Any thoughts how to port the regexp to MySQL? Or maybe you know any other way to check if the string is valid UTF-8? UPDATE: I need this check working on the MySQL as I need to run it on the server to correct broken tables. I can't pass the data through a script as the database is around 1TB.

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  • Why do we use the Pythagorean theorem in game physics?

    - by Starkers
    I've recently learned that we use Pythagorean theorem a lot in our physics calculations and I'm afraid I don't really get the point. Here's an example from a book to make sure an object doesn't travel faster than a MAXIMUM_VELOCITY constant in the horizontal plane: MAXIMUM_VELOCITY = <any number>; SQUARED_MAXIMUM_VELOCITY = MAXIMUM_VELOCITY * MAXIMUM_VELOCITY; function animate(){ var squared_horizontal_velocity = (x_velocity * x_velocity) + (z_velocity * z_velocity); if( squared_horizontal_velocity <= SQUARED_MAXIMUM_VELOCITY ){ scalar = squared_horizontal_velocity / SQUARED_MAXIMUM_VELOCITY; x_velocity = x_velocity / scalar; z_velocity = x_velocity / scalar; } } Let's try this with some numbers: An object is attempting to move 5 units in x and 5 units in z. It should only be able to move 5 units horizontally in total! MAXIMUM_VELOCITY = 5; SQUARED_MAXIMUM_VELOCITY = 5 * 5; SQUARED_MAXIMUM_VELOCITY = 25; function animate(){ var x_velocity = 5; var z_velocity = 5; var squared_horizontal_velocity = (x_velocity * x_velocity) + (z_velocity * z_velocity); var squared_horizontal_velocity = 5 * 5 + 5 * 5; var squared_horizontal_velocity = 25 + 25; var squared_horizontal_velocity = 50; // if( squared_horizontal_velocity <= SQUARED_MAXIMUM_VELOCITY ){ if( 50 <= 25 ){ scalar = squared_horizontal_velocity / SQUARED_MAXIMUM_VELOCITY; scalar = 50 / 25; scalar = 2.0; x_velocity = x_velocity / scalar; x_velocity = 5 / 2.0; x_velocity = 2.5; z_velocity = z_velocity / scalar; z_velocity = 5 / 2.0; z_velocity = 2.5; // new_horizontal_velocity = x_velocity + z_velocity // new_horizontal_velocity = 2.5 + 2.5 // new_horizontal_velocity = 5 } } Now this works well, but we can do the same thing without Pythagoras: MAXIMUM_VELOCITY = 5; function animate(){ var x_velocity = 5; var z_velocity = 5; var horizontal_velocity = x_velocity + z_velocity; var horizontal_velocity = 5 + 5; var horizontal_velocity = 10; // if( horizontal_velocity >= MAXIMUM_VELOCITY ){ if( 10 >= 5 ){ scalar = horizontal_velocity / MAXIMUM_VELOCITY; scalar = 10 / 5; scalar = 2.0; x_velocity = x_velocity / scalar; x_velocity = 5 / 2.0; x_velocity = 2.5; z_velocity = z_velocity / scalar; z_velocity = 5 / 2.0; z_velocity = 2.5; // new_horizontal_velocity = x_velocity + z_velocity // new_horizontal_velocity = 2.5 + 2.5 // new_horizontal_velocity = 5 } } Benefits of doing it without Pythagoras: Less lines Within those lines, it's easier to read what's going on ...and it takes less time to compute, as there are less multiplications Seems to me like computers and humans get a better deal without Pythagorean theorem! However, I'm sure I'm wrong as I've seen Pythagoras' theorem in a number of reputable places, so I'd like someone to explain me the benefit of using Pythagorean theorem to a maths newbie. Does this have anything to do with unit vectors? To me a unit vector is when we normalize a vector and turn it into a fraction. We do this by dividing the vector by a larger constant. I'm not sure what constant it is. The total size of the graph? Anyway, because it's a fraction, I take it, a unit vector is basically a graph that can fit inside a 3D grid with the x-axis running from -1 to 1, z-axis running from -1 to 1, and the y-axis running from -1 to 1. That's literally everything I know about unit vectors... not much :P And I fail to see their usefulness. Also, we're not really creating a unit vector in the above examples. Should I be determining the scalar like this: // a mathematical work-around of my own invention. There may be a cleverer way to do this! I've also made up my own terms such as 'divisive_scalar' so don't bother googling var divisive_scalar = (squared_horizontal_velocity / SQUARED_MAXIMUM_VELOCITY); var divisive_scalar = ( 50 / 25 ); var divisive_scalar = 2; var multiplicative_scalar = (divisive_scalar / (2*divisive_scalar)); var multiplicative_scalar = (2 / (2*2)); var multiplicative_scalar = (2 / 4); var multiplicative_scalar = 0.5; x_velocity = x_velocity * multiplicative_scalar x_velocity = 5 * 0.5 x_velocity = 2.5 Again, I can't see why this is better, but it's more "unit-vector-y" because the multiplicative_scalar is a unit_vector? As you can see, I use words such as "unit-vector-y" so I'm really not a maths whiz! Also aware that unit vectors might have nothing to do with Pythagorean theorem so ignore all of this if I'm barking up the wrong tree. I'm a very visual person (3D modeller and concept artist by trade!) and I find diagrams and graphs really, really helpful so as many as humanely possible please!

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  • What's the difference or purpose of a file format like ELF when flat binaries take up less space and can do the same thing?

    - by Sinister Clock
    I will give a better description now. In Linux driver development you need to follow a specification using an ELF file format as a finalized executable, i.e., that right there is not flat, it has headers, entry fields, and is basically carrying more weight than just a flat binary with opcodes. What is the purpose or in-depth difference of a Linux ELF file for a driver to interact with the video hardware, and, say, a bare, flat x86 16-bit binary I write that makes use of emulated graphics mode on a graphics card and writes to memory(besides the fact that the Linux driver probably is specific to making full use of the hardware and not just the emulated, backwards compatible memory accessing scheme). To sum it up, what is a difference or purpose of a binary like ELF with different headers and settings and just a flat binary with the necessary opcodes/instructions/data to do the same thing, just without any specific format? Example: Windows uses PE, Mac uses Mach-O/PEF, Linux uses ELF/FATELF, Unix uses COFF. What do any of them really mean or designate if you can just go flat, especially with a device driver which is system software.

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  • Can I use rest-client to POST a binary file to HTTP without multipart?

    - by Angela
    I have tried to do the following, but the web-service is NOT REST and does not take multi-part. What do I do in order to POST the image? @response = RestClient.post('http://www.postful.com/service/upload', {:upload => { :file => File.new("#{@postalcard.postalimage.path}",'rb') } }, {"Content-Type" => @postalcard.postalimage.content_type, "Content-Length" => @postalcard.postalimage.size, "Authorization" => 'Basic xxxxxx' } # end headers ) #close arguments to Restclient.post

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  • can't explain NullPointerException

    - by John Pope
    In the following code, i have a method to get a Vector of persons with the same zodiac sign. persoane is a Vector. I keep getting a NullPointerException at the if condition (persoane is definetly not null). I am unable to see why. Any help would be greatly appreciated public Vector<Persoana> cautaDupaZodie(String zodie) { Vector<Persoana> rezultat= new Vector<Persoana>(); for(int i=0; i<persoane.size(); i++) { if(persoane.get(i).getData().getZodie().equals(zodie)) //the exception occurs here { rezultat.add(persoane.get(i)); } } return rezultat; }

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  • Is it possible to build a Mac binary on a non-Mac unix machine?

    - by nbolton
    I would like to set up a Mac buildbot slave, but unfortunately it's not possible to install Mac OS X 10.5 on my XenServer hypervisor. So, I've had an idea, but not quite sure whether or not it'll work. The application is C++, and on Mac it's compile using GNU Make. I have a Mac desktop PC, and I was hoping I could copy the .h and .lib files on to a Linux box, and try to build against the Mac headers: #include <mach-o/dyld.h> #include <AvailabilityMacros.h>

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  • Is there a module that implements an efficient array type in Erlang?

    - by dsmith
    I have been looking for an array type with the following characteristics in Erlang. append(vector(), term()) O(1) nth(Idx, vector()) O(1) set(Idx, vector(), term()) O(1) insert(Idx, vector(), term()) O(N) remove(Idx, vector()) O(N) I normally use a tuple for this purpose, but the performance characteristics are not what I would want for large N. My testing shows the following performance characteristics... erlang:append_element/2 O(N). erlang:setelement/3 O(N). I have started on a module based on the clojure.lang.PersistentVector implementation, but if it's already been done I won't reinvent the wheel.

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  • Can Google App Engine be used for "check for updated" and download binary file web service?

    - by Tofrizer
    Hi, I'm a Google App Engine newbie and would be grateful for any help. I have an iPhone app which sources data from an sqlite db stored localling on the device. I'd like to set up a Google App Engine web service which my iPhone client will talk to and check if there is a newer version of the sqlite database it needs to download. So iPhone client hits the web service with some kind of version number/timestamp and if there is a newer file, the App Engine will notify the client and the client will then request the new database to download which the App Engine will serve. Is it possible to set up a web service in Google App Engine to do this? Could anyone point me to any sample code / tutorials please? Many Thanks

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  • Inline function and calling cost in C

    - by Eonil
    I'm making a vector/matrix library. (GCC, ARM NEON, iPhone) typedef struct{ float v[4]; } Vector; typedef struct{ Vector v[4]; } Matrix; I passed struct data as pointer to avoid performance degrade from data copying when calling function. So I thought designed function like this: void makeTranslation(const Vector* factor, Matrix* restrict result); But, if function is inline, is there any reason to pass values as pointer for performance? Do those variables copied too? How about register and caches? inline Matrix makeTranslation(Vector factor) __attribute__ ((always_inline)); How do you think about calling costs of each cases?

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  • How can one check for a binary in the GAC in a WiX installer?

    - by Billy ONeal
    I have an application which depends on the Team Foundation Server "Object Model", and looks for such binaries in the GAC. This means that clients of the app need to install Visual Studio, or the standalone TFS object model in order to use the application. I would like the installer to detect that the TFS bits aren't installed, and fail to install appropriately if they are not. Is such a thing possible?

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  • not getting updates

    - by gknarayana
    when i check for updates the message is "W:Failed to fetch cdrom://Ubuntu 12.04 LTS _Precise Pangolin_ - Release i386 (20120423)/dists/precise/main/binary-i386/Packages Please use apt-cdrom to make this CD-ROM recognized by APT. apt-get update cannot be used to add new CD-ROMs , W:Failed to fetch cdrom://Ubuntu 12.04 LTS _Precise Pangolin_ - Release i386 (20120423)/dists/precise/restricted/binary-i386/Packages Please use apt-cdrom to make this CD-ROM recognized by APT. apt-get update cannot be used to add new CD-ROMs , W:Failed to fetch cdrom://Ubuntu 11.10 _Oneiric Ocelot_ - Release i386 (20111012)/dists/oneiric/main/binary-i386/Packages Please use apt-cdrom to make this CD-ROM recognized by APT. apt-get update cannot be used to add new CD-ROMs , W:Failed to fetch cdrom://Ubuntu 11.10 _Oneiric Ocelot_ - Release i386 (20111012)/dists/oneiric/restricted/binary-i386/Packages Please use apt-cdrom to make this CD-ROM recognized by APT. apt-get update cannot be used to add new CD-ROMs , E:Some index files failed to download. They have been ignored, or old ones used instead." please suggest what i should do

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  • Linux, GNU GCC, ld, version scripts and the ELF binary format -- How does it work??

    - by themoondothshine
    Hey all, I'm trying to learn more about library versioning in Linux and how to put it all to work. Here's the context: -- I have two versions of a dynamic library which expose the same set of interfaces, say libsome1.so and libsome2.so. -- An application is linked against libsome1.so. -- This application uses libdl.so to dynamically load another module, say libmagic.so. -- Now libmagic.so is linked against libsome2.so. Obviously, without using linker scripts to hide symbols in libmagic.so, at run-time all calls to interfaces in libsome2.so are resolved to libsome1.so. This can be confirmed by checking the value returned by libVersion() against the value of the macro LIB_VERSION. -- So I try next to compile and link libmagic.so with a linker script which hides all symbols except 3 which are defined in libmagic.so and are exported by it. This works... Or at least libVersion() and LIB_VERSION values match (and it reports version 2 not 1). -- However, when some data structures are serialized to disk, I noticed some corruption. In the application's directory if I delete libsome1.so and create a soft link in its place to point to libsome2.so, everything works as expected and the same corruption does not happen. I can't help but think that this may be caused due to some conflict in the run-time linker's resolution of symbols. I've tried many things, like trying to link libsome2.so so that all symbols are alised to symbol@@VER_2 (which I am still confused about because the command nm -CD libsome2.so still lists symbols as symbol and not symbol@@VER_2)... Nothing seems to work!!! Help!!!!!! Edit: I should have mentioned it earlier, but the app in question is Firefox, and libsome1.so is libsqlite3.so shipped with it. I don't quite have the option of recompiling them. Also, using version scripts to hide symbols seems to be the only solution right now. So what really happens when symbols are hidden? Do they become 'local' to the SO? Does rtld have no knowledge of their existence? What happens when an exported function refers to a hidden symbol?

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  • c struct map to ruby using SWIG

    - by pierr
    Hi, Is there any body can confirm the description here is true? My experience is that I can not use Example::Vector.new at all. C/C++ structs are wrapped as Ruby classes, with accessor methods (i.e. "getters" and "setters") for all of the struct members. For example, this struct declaration: struct Vector { double x, y; }; gets wrapped as a Vector class, with Ruby instance methods x, x=, y and y=. These methods can be used to access structure data from Ruby as follows: $ irb irb(main):001:0> require 'Example' true irb(main):002:0> f = Example::Vector.new #<Example::Vector:0x4020b268> irb(main):003:0> f.x = 10 nil irb(main):004:0> f.x 10.0

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  • what is the best method of concatenating a series of binary files into one file?

    - by Andrew
    hello everyone i have a series of PDF byte arrays in a arraylist files that i wish to concatenate into one file, currently when the PDF application trys to open the file is it corrupted: foreach (byte[] array in files) { using (Stream s = new MemoryStream(downloadbytes)) { s.Write(array, 0, array.Length); } } downloadbytes is the resultant concatenated array of bytes below is another implementation which also failed foreach (byte[] array in files) { System.Buffer.BlockCopy(array, 0, downloadbytes, offset, array.Length); offset += array.Length; } any pointers?

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