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  • j2me bluetooth client. Function startInquiry nothing found.

    - by Hugi
    I develop simple j2me bluetooth client and have problem with bluetooth device search. Function startInquiry nothing found. Client : nokia 5220 Server : my pc with bluetooth adapter All bluetooth devices is on. /* * To change this template, choose Tools | Templates * and open the template in the editor. */ import javax.microedition.midlet.*; import javax.bluetooth.*; import java.util.Vector; import javax.microedition.lcdui.*; /** * @author ????????????? */ public class Midlet extends MIDlet implements DiscoveryListener { private static Vector vecDevices=new Vector(); private static String connectionURL=null; private LocalDevice localDevice; private DiscoveryAgent agent; private RemoteDevice remoteDevice; private RemoteDevice[] devList; private Display display; private Form form; public void startApp() { display = Display.getDisplay(this); form = new Form( "Client" ); try { localDevice = LocalDevice.getLocalDevice(); } catch( BluetoothStateException e ) { e.printStackTrace(); } form.append("Address: "+localDevice.getBluetoothAddress()+"\n\n"); form.append("Name: "+localDevice.getFriendlyName()+"\n\n"); try { agent = localDevice.getLocalDevice().getDiscoveryAgent(); form.append("Starting device inquiry... \n\n"); boolean si = agent.startInquiry(DiscoveryAgent.GIAC, this); if ( si ) { form.append("true"); } else { form.append("false"); } } catch( BluetoothStateException e ) { } int deviceCount = vecDevices.size(); if(deviceCount <= 0){ form.append("No Devices Found ."); } else{ //print bluetooth device addresses and names in the format [ No. address (name) ] form.append("Bluetooth Devices: "); for (int i = 0; i < deviceCount; i++) { remoteDevice=(RemoteDevice)vecDevices.elementAt(i); form.append( remoteDevice.getBluetoothAddress() ); } } display.setCurrent(form); } public void pauseApp() { } public void destroyApp(boolean unconditional) { } public void deviceDiscovered(RemoteDevice btDevice, DeviceClass cod) { //add the device to the vector if(!vecDevices.contains(btDevice)){ vecDevices.addElement(btDevice); } } public void inquiryCompleted(int discType) { } //implement this method since services are not being discovered public void servicesDiscovered(int transID, ServiceRecord[] servRecord) { if(servRecord!=null && servRecord.length>0){ connectionURL=servRecord[0].getConnectionURL(0,false); } } //implement this method since services are not being discovered public void serviceSearchCompleted(int transID, int respCode) { } }

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  • How do I send information to an HLSL effect in DirectX 10?

    - by pypmannetjies
    I'd like to send my view vector to an ID3D10Effect variable in order to calculate specular lighting. How do I send a vector or even just scalar values to the HLSL from the running DirectX program? I want to do something like render() { //do transformations D3DXMatrix view = camera->getViewMatrix(); basicEffect.setVariable(viewVector, view); //render stuff }

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  • Why does std::map operator[] create an object if the key doesn't exist?

    - by n1ck
    Hi, I'm pretty sure I already saw this question somewhere (comp.lang.c++? Google doesn't seem to find it there either) but a quick search here doesn't seem to find it so here it is: Why does the std::map operator[] create an object if the key doesn't exist? I don't know but for me this seems counter-intuitive if you compare to most other operator[] (like std::vector) where if you use it you must be sure that the index exists. I'm wondering what's the rationale for implementing this behavior in std::map. Like I said wouldn't it be more intuitive to act more like an index in a vector and crash (well undefined behavior I guess) when accessed with an invalid key? Refining my question after seeing the answers: Ok so far I got a lot of answers saying basically it's cheap so why not or things similar. I totally agree with that but why not use a dedicated function for that (I think one of the comment said that in java there is no operator[] and the function is called put)? My point is why doesn't map operator[] work like a vector? If I use operator[] on an out of range index on a vector I wouldn't like it to insert an element even if it was cheap because that probably mean an error in my code. My point is why isn't it the same thing with map. I mean, for me, using operator[] on a map would mean: i know this key already exist (for whatever reason, i just inserted it, I have redundancy somewhere, whatever). I think it would be more intuitive that way. That said what are the advantage of doing the current behavior with operator[] (and only for that, I agree that a function with the current behavior should be there, just not operator[])? Maybe it give clearer code that way? I don't know. Another answer was that it already existed that way so why not keep it but then, probably when they (the ones before stl) choose to implement it that way they found it provided an advantage or something? So my question is basically: why choose to implement it that way, meaning a somewhat lack of consistency with other operator[]. What benefit do it give? Thanks

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  • Logic error for Gauss elimination

    - by iwanttoprogram
    Logic error problem with the Gaussian Elimination code...This code was from my Numerical Methods text in 1990's. The code is typed in from the book- not producing correct output... Sample Run: SOLUTION OF SIMULTANEOUS LINEAR EQUATIONS USING GAUSSIAN ELIMINATION This program uses Gaussian Elimination to solve the system Ax = B, where A is the matrix of known coefficients, B is the vector of known constants and x is the column matrix of the unknowns. Number of equations: 3 Enter elements of matrix [A] A(1,1) = 0 A(1,2) = -6 A(1,3) = 9 A(2,1) = 7 A(2,2) = 0 A(2,3) = -5 A(3,1) = 5 A(3,2) = -8 A(3,3) = 6 Enter elements of [b] vector B(1) = -3 B(2) = 3 B(3) = -4 SOLUTION OF SIMULTANEOUS LINEAR EQUATIONS The solution is x(1) = 0.000000 x(2) = -1.#IND00 x(3) = -1.#IND00 Determinant = -1.#IND00 Press any key to continue . . . The code as copied from the text... //Modified Code from C Numerical Methods Text- June 2009 #include <stdio.h> #include <math.h> #define MAXSIZE 20 //function prototype int gauss (double a[][MAXSIZE], double b[], int n, double *det); int main(void) { double a[MAXSIZE][MAXSIZE], b[MAXSIZE], det; int i, j, n, retval; printf("\n \t SOLUTION OF SIMULTANEOUS LINEAR EQUATIONS"); printf("\n \t USING GAUSSIAN ELIMINATION \n"); printf("\n This program uses Gaussian Elimination to solve the"); printf("\n system Ax = B, where A is the matrix of known"); printf("\n coefficients, B is the vector of known constants"); printf("\n and x is the column matrix of the unknowns."); //get number of equations n = 0; while(n <= 0 || n > MAXSIZE) { printf("\n Number of equations: "); scanf ("%d", &n); } //read matrix A printf("\n Enter elements of matrix [A]\n"); for (i = 0; i < n; i++) for (j = 0; j < n; j++) { printf(" A(%d,%d) = ", i + 1, j + 1); scanf("%lf", &a[i][j]); } //read {B} vector printf("\n Enter elements of [b] vector\n"); for (i = 0; i < n; i++) { printf(" B(%d) = ", i + 1); scanf("%lf", &b[i]); } //call Gauss elimination function retval = gauss(a, b, n, &det); //print results if (retval == 0) { printf("\n\t SOLUTION OF SIMULTANEOUS LINEAR EQUATIONS\n"); printf("\n\t The solution is"); for (i = 0; i < n; i++) printf("\n \t x(%d) = %lf", i + 1, b[i]); printf("\n \t Determinant = %lf \n", det); } else printf("\n \t SINGULAR MATRIX \n"); return 0; } /* Solves the system of equations [A]{x} = {B} using */ /* the Gaussian elimination method with partial pivoting. */ /* Parameters: */ /* n - number of equations */ /* a[n][n] - coefficient matrix */ /* b[n] - right-hand side vector */ /* *det - determinant of [A] */ int gauss (double a[][MAXSIZE], double b[], int n, double *det) { double tol, temp, mult; int npivot, i, j, l, k, flag; //initialization *det = 1.0; tol = 1e-30; //initial tolerance value npivot = 0; //mult = 0; //forward elimination for (k = 0; k < n; k++) { //search for max coefficient in pivot row- a[k][k] pivot element for (i = k + 1; i < n; i++) { if (fabs(a[i][k]) > fabs(a[k][k])) { //interchange row with maxium element with pivot row npivot++; for (l = 0; l < n; l++) { temp = a[i][l]; a[i][l] = a[k][l]; a[k][l] = temp; } temp = b[i]; b[i] = b[k]; b[k] = temp; } } //test for singularity if (fabs(a[k][k]) < tol) { //matrix is singular- terminate flag = 1; return flag; } //compute determinant- the product of the pivot elements *det = *det * a[k][k]; //eliminate the coefficients of X(I) for (i = k; i < n; i++) { mult = a[i][k] / a[k][k]; b[i] = b[i] - b[k] * mult; //compute constants for (j = k; j < n; j++) //compute coefficients a[i][j] = a[i][j] - a[k][j] * mult; } } //adjust the sign of the determinant if(npivot % 2 == 1) *det = *det * (-1.0); //backsubstitution b[n] = b[n] / a[n][n]; for(i = n - 1; i > 1; i--) { for(j = n; j > i + 1; j--) b[i] = b[i] - a[i][j] * b[j]; b[i] = b[i] / a[i - 1][i]; } flag = 0; return flag; } The solution should be: 1.058824, 1.823529, 0.882353 with det as -102.000000 Any insight is appreciated...

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  • Projection on a plane using a 2*3 matrix

    - by leipäjuusto
    Hello, I can easily draw the projection of a 3D set of points onto the plane with normal vector (1,1,1), by using the matrix (-sqrt(3)/2 sqrt(3)/2 0) (-1/2 -1/2 1). I want to do the same thing, but for a projection onto an arbitrary plane with normal vector (a,b,c) instead of (1,1,1). How to find the matrix? Thanks in advance!

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  • Function templates for arbitrary STL containers containing arbitrary types.

    - by Chad Brewbaker
    I have an arbitrary STL container C, which contains elements of an arbitrary type T. I want to create an std::vector that has a copy of all the elements. What is the cleanest way to do this? template <typename C> void myfunction(C container){ /*Derive the type T of elements within the container*/ std::vector<T> mystack; /* Iterate over container and push_back() the elements into mystack*/ }

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  • Providing *implicit* conversion operator for template specialization

    - by Neil G
    I have a templated sparse_vector<T> class, and I am also using Boost UBLAS. How would I provide implicit conversions between sparse_vector<double> and boost::numeric::ublas::compressed_vector<double>? I would also like to provide similar conversions between std::vector<double> and boost::numeric::ublas::vector<double>. (I am using gcc 4.4 with C++0x enabled.)

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  • Does Boost work with IntervalZero RTX 2009?

    - by cs-79
    Hi all Rtx experts, Have anyone implemented hard real-time app on IntervalZero Rtx environment using Boost libraries? I wish to use the Boost `unordered` data structures instead of solely relying on STL::Vector. Or Array/Vector is the only data structure supported by Rtx? * Off topic question: Can we use STL::String instead of char pointer for string in Rtx? Thanks.

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  • What is wrong with this C++ Code ?

    - by mr.bio
    Hi .. i am a beginner and i have a problem : this code doesnt compile : main.cpp: #include <stdlib.h> #include "readdir.h" #include "mysql.h" #include "readimage.h" int main(int argc, char** argv) { if (argc>1){ readdir(argv[1]); // test(); return (EXIT_SUCCESS); } std::cout << "Bitte Pfad angeben !" << std::endl ; return (EXIT_FAILURE); } readimage.cpp #include <Magick++.h> #include <iostream> #include <vector> using namespace Magick; using namespace std; void readImage(std::vector<string> &filenames) { for (unsigned int i = 0; i < filenames.size(); ++i) { try { Image img("binary/" + filenames.at(i)); for (unsigned int y = 1; y < img.rows(); y++) { for (unsigned int x = 1; x < img.columns(); x++) { ColorRGB rgb(img.pixelColor(x, y)); // cout << "x: " << x << " y: " << y << " : " << rgb.red() << endl; } } cout << "done " << i << endl; } catch (Magick::Exception & error) { cerr << "Caught Magick++ exception: " << error.what() << endl; } } } readimage.h #ifndef _READIMAGE_H #define _READIMAGE_H #include <Magick++.h> #include <iostream> #include <vector> #include <string> using namespace Magick; using namespace std; void readImage(vector<string> &filenames) #endif /* _READIMAGE_H */ If want to compile it with this code : g++ main.cpp Magick++-config --cflags --cppflags --ldflags --libs readimage.cpp i get this error message : main.cpp:5: error: expected initializer before ‘int’ i have no clue , why ? :( Can somebody help me ? :)

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  • C++ stl collections or linked lists

    - by Lucas
    I'm developing a OpenGL based simulation in C++. I'm optmizing my code now and i see throughout the code the frequently use of std:list and std:vector. What is the more performatic: to continue using C++ stl data structs or a pointer based linked list? The main operation that involve std::list and std::vector is open a iterator and loop through all items in the data structs and apply some processing

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  • Perfect Forwarding to async lambda

    - by Alexander Kondratskiy
    I have a function template, where I want to do perfect forwarding into a lambda that I run on another thread. Here is a minimal test case which you can directly compile: #include <thread> #include <future> #include <utility> #include <iostream> #include <vector> /** * Function template that does perfect forwarding to a lambda inside an * async call (or at least tries to). I want both instantiations of the * function to work (one for lvalue references T&, and rvalue reference T&&). * However, I cannot get the code to compile when calling it with an lvalue. * See main() below. */ template <typename T> std::string accessValueAsync(T&& obj) { std::future<std::string> fut = std::async(std::launch::async, [](T&& vec) mutable { return vec[0]; }, std::forward<T>(obj)); return fut.get(); } int main(int argc, char const *argv[]) { std::vector<std::string> lvalue{"Testing"}; // calling with what I assume is an lvalue reference does NOT compile std::cout << accessValueAsync(lvalue) << std::endl; // calling with rvalue reference compiles std::cout << accessValueAsync(std::move(lvalue)) << std::endl; // I want both to compile. return 0; } For the non-compiling case, here is the last line of the error message which is intelligible: main.cpp|13 col 29| note: no known conversion for argument 1 from ‘std::vector<std::basic_string<char> >’ to ‘std::vector<std::basic_string<char> >&’ I have a feeling it may have something to do with how T&& is deduced, but I can't pinpoint the exact point of failure and fix it. Any suggestions? Thank you! EDIT: I am using gcc 4.7.0 just in case this could be a compiler issue (probably not)

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  • R - indirectly calling a matrix using a string

    - by Boris Senderovich
    Example: There is a matrix of data called VE There is a vector of string where the first element is the string VE. I need to indirectly call the string and be able to access data. For example if I need the 6th column of matrix VE then I want to do: Vector[1][,6] Essentially I need R to start reading those string as if they are the matrix names that are already in this page. I need this syntax to be dynamic because I am putting it in a loop.

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  • Quaternion Cameras and projectile vectors

    - by Tom J Nowell
    In our software we have a camera based on mouse movement, and a quarternion at its heart. We want to fire projectiles from this position, which we can do, however we want to use the camera to aim. The projectile takes a vector which it will add to its position each game frame. How do we acquire such a vector from a given camera/quaternion?

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  • Matlab - Find point of intersection between two vectors

    - by Silv3rSurf
    I have a very simple matlab question. What is the easiest way to find the point of intersection between two vectors. I am not familiar with the various matlab fuctions -- it seems like there should be one for this. For example if I have one vector from (0,0) to (6,6) and another vector from (0,6) to (6,0), I need to determine that they intersect at (3,3) Thanks.

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  • Best way to have common class shared by both C++ and Ruby?

    - by shuttle87
    I am currently working on a project where a team of us are designing a game, all of us are proficient in ruby and some (but not all) of us are proficient in c++. Initially we made the backend in ruby but we ported it to c++ for more speed. The c++ port of the backend has exactly the same features and algorithms as the original ruby code. However we still have a bunch of code in ruby that does useful things but we want it to now get the data from the c++ classes. Our first thought was that we could save some of the data structures in something like XML or redis and call that, but some of the developers don't like that idea. We don't need anything particularly complex data structures to be passed between the different parts of the code, just tuples, strings and ints. Is there any way of integrating the ruby code so that it can call the c++ stuff natively? Will we need to embed code? Will we have to make a ruby extension? If so are there any good resources/tutorials you could suggest? For example say we have this code in the c++ backend: class The_game{ private: bool printinfo; //print the player diagnostic info at the beginning if true int numplayers; std::vector<Player*> players; string current_action; int action_is_on; // the index of the player in the players array that the action is now on //more code here public: Table(std::vector<Player *> in_players, std::vector<Statistics *> player_stats ,const int in_numplayers); ~Table(); void play_game(); History actions_history; }; class History{ private: int action_sequence_number; std::vector<Action*> hand_actions; public: void print_history(); void add_action(Action* the_action_to_be_added); int get_action_sequence_number(){ return action_sequence_number;} bool history_actions_are_equal(); int last_action_size(int street,int number_of_actions_ago); History(); ~History(); }; Is there any way to natively call something in the actions_history via The_game object in ruby? (The objects in the original ruby code all had the same names and functionality) By this I mean: class MyRubyClass def method1(arg1) puts arg1 self.f() # ... but still available puts cpp_method.the_current_game.actions_history.get_action_sequence_number() end # Constructor: def initialize(arg) puts "In constructor with arg #{arg}" #get the c++ object here and call it cpp_method end end Is this possible? Any advice or suggestions are appreciated.

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  • length between 2 values

    - by alex
    In R, what is the most efficient way to count the length between 2 values. for example, i have vector x , which are all randomly choose from 1 to 100, how can i find out the length between the first"2" and first"40", x=(1,2,3,4,5,6,7,40,1,2,3,21,4,1,23,4,43,23,4,12,3,43,5,36,3,45,12,31,3,4,23,41,23,5,53,45,3,7,6,36) for this vector, the answer should be 5 and 6

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  • How do I calculate the average direction of two vectors

    - by Mike Broughton
    Hi, I am writing and opengl based iphone app and would like to allow a user to translate around a view based on the direction that they move two fingers on the screen. For one finger I know I could just calculate the vector from the start position to the current position of the users finger and then find the unit vector of this to get just the direction, but I don't know how I would do this for two fingers, I don't think adding the components of the vectors and calculating the average would work so I'm pretty much stuck... thanks in advance

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  • Can IDL create a contour plot colorbar like this?

    - by Carthage
    At the bottom of this image, you'll see a nice colorbar that matches the colors of the graph correctly: http://stribog.cc.umanitoba.ca/ceos/20100517_00z_prod/ I couldn't find anything that created a color bar with exactly the colors I wanted, it always seemed to involve a spectrum that included colors I didn't use. I have a vector of colors I use for my data. Is there I way I can use that vector to create a color bar with only those colors?

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  • Best way to render Tesselated Objects (OpenGL)

    - by user146780
    I'm using the GLUTesselator for Polygons. Right now the vertex callback does glvertex2f and gltex2f. Would it be better simply to collect the verticies from the vertex callback in a std::vector then use gldrawarrays()? Or would this actually be less efficient since it has to put the verts and texture coordinates in a vector? Thanks

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  • Best Java thread-safe locking mechanism for collections?

    - by Simon
    What would be the least-slow thread-safe mechanism for controlling multiple accesses to a collection in Java? I am adding objects to the top of a collection and i am very unsure what would be the best performing collection. Would it be a vector or a queue? I originally thought an ArrayList would be fast but i ran some experiments and it was very slow. EDIT: In my insertion testing a Vector delared using volatile seems to be the fastest?

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  • Split a binary file into chunks c++

    - by L4nce0
    I've been bashing my head against trying to first divide up a file into chunks, for the purpose of sending over sockets. I can read / write a file easily without splitting it into chunks. The code below runs, works, kinda. It will write a textfile and has a garbage character. Which if this was just for txt, no problem. Jpegs aren't working with said garbage. Been at it for a few days, so I've done my research, and it's time to get some help. I do want to stick strictly to binary readers, as this need to handle any file. I've seen a lot of slick examples out there. (none of them worked for me with jpgs) Mostly something along the lines of while(file)... I subscribe to the, if you know the size, use a for-loop, not a while-loop camp. Thank you for the help!! vector<char*> readFile(const char* fn){ vector<char*> v; ifstream::pos_type size; char * memblock; ifstream file; file.open(fn,ios::in|ios::binary|ios::ate); if (file.is_open()) { size = fileS(fn); file.seekg (0, ios::beg); int bs = size/3; // arbitrary. Actual program will use the socket send size int ws = 0; int i = 0; for(i = 0; i < size; i+=bs){ if(i+bs > size) ws = size%bs; else ws = bs; memblock = new char [ws]; file.read (memblock, ws); v.push_back(memblock); } } else{ exit(-4); } return v; } int main(int argc, char **argv) { vector<char*> v = readFile("foo.txt"); ofstream myFile ("bar.txt", ios::out | ios::binary); for(vector<char*>::iterator it = v.begin(); it!=v.end(); ++it ){ myFile.write(*it,strlen(*it)); } }

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  • BSOD - probably video card prob

    - by Shimmy
    I'm receiving the following BSOD: I've tried installing the latest driver from nVidia (296.10), but it says "NVIDIA installer cannot continue", "The graphics driver could not find compatible graphics hardware.": I installed it manually at device manager, but problem still occurs. The problem does not happen in safe mode at all. Note: After restarting the computer when seeing this BSOD, the BIOS welcome screen is full of random black dots spread around: Any solutions? Update: I've tried disabling Aero by following this guide, but that didn't help.

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