Visual C++ :: Pthreads - Solve System Of Equations By Gauss-Jordan Method
Dec 15, 2012
I have a problem: solve the system of equations by the Gauss-Jordan methods with pthreads. I have a big matrix A (for example 2000x2000), so i must solve Ax = b. Before I devide matrix to number of threads and each thread must work only with his peace of matrix.
Code:
#include <iostream>
#include "synchronize.h"
#include <pthread.h>
using namespace std;
typedef struct _ARGS {
int thread_count;
int thread_number;
[Code] .....
I write it on Ubuntu, and when I compile [g++ main.cpp -o main -lpthread -lm] the it works good(for example, if in 1 thread I get time_of_working = 10 sec, on 2 threads time_of_working = 5.4, i.e. about 2 times faster ), if I compile like this [g++ main.cpp -o main -lpthread -lm -O3] it is only 1.2-1.3 times faster.
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Dec 14, 2014
I am trying to write a code that solves a system of linear equations such as A*B=C. My system has a dimension equal to 1600. The matrix A cab be separated into 4 sub matrices and each can be handled by a different thread. I tried to solve this using the following code:
int main() {
int count = 0;
//Inputing matrix A
ifstream matrix;
matrix.open("example.txt");
[Code] ....
Although the above code gives the correct answer, the time needs to find the solution is bigger than that needed without using threads.
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Nov 10, 2013
Calculated by the explicit scheme. Produces some very large numbers.
task:
[math] U_t = 3 (1,1-0,5 x) U_ {xx} + e ^ t-1 [/ math]
[math] U (0, t) = 0 [/ math]
[math] U (1, t) = 0 [/ math]
[math] U (x, 0) = 0.01 (1-x) x [/ math]
Need to find a solution with accuracy [math] 0.0001 [/ math] on the interval [math] T = 1 / a ^ *, where a ^ * = max a (x, t) [/ math] Plot graphs of functions [math] u (x ^ *, t), u (x, jt ^ *) [/ math] where [math] x ^ * = 0.6, t ^ * = T/10, j = 1,2,4 [/ math]
explicit difference scheme is as follows:
([math] $ u_t ^ {j +1}-u_i ^ j) / tau = 3 (1,1-0,5 x_i) (u_ {i +1} ^ {j}-2u_i ^ j + u_ {i -1} ^ j) / h ^ 2 + e ^ {t_j} +1 $ $ [/ math]
code of the program:
int main ( void ) {
setlocale(LC_ALL, "rus");
int I = 10, J = 30, i, j;
double T = 1.0/ pow(3.3, 0.5), h_x = 1.0/ I, h_t = T/ J, epsilon = h_t + pow(h_x, 2), c;
double **u = new double *[I + 1];
for (i = 0; i <= I; i++) u[i] = new double [J + 1];
[code]....
displays the following:
[URL]
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Dec 22, 2012
I am using matlab R2o11 in which the programming medium is c++. I am having these variables=
T=373 t0 376
V=0.09 to 1
P=T/V
I just need a result showing ... First it should take T=373 and solve the equation using all volume values. Then it takes another temperature and do the same.
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May 20, 2013
I'm quite new to openMP, mostly used pthreads and mpi before. Now I like to tinker a bit with openMP, but haven't found any good docs, reference list or similar.
What's the equivalent to pthread's mutex lock in openMP?
Code:
#pragma omp parallel for
for(i=0; i<n ; i++){
// Do something intelligent...
// If needed handle a shared variable.
}
How do I protect the shared variable?
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Nov 23, 2013
I am working on the producer-consumer problem and am mostly happy with what I have except for one remaining issue. I am using pthreads for consumers and producers on a FIFO, and synchronizing using a combination of semaphores and mutexes. Things seem to work fine, except that my consumers seem unable to tell when there may be more data coming into the FIFO.
I need to be able to determine not just when the FIFO is empty (it gets emptied every time a consumer thread runs) but when ALL producers have detached from it - that's when my consumers should pthread_exit, and not before that. I have read conflicting information on how FIFOs work in terms of EOF and have been unable to get it working.
(NOTE: that's what I *think* the problem is... It's my first time working with pthreads, so there may be other issues I am not even aware of).
In any case, my code is below. I am running it on a Linux VM on top of Windows, if that makes any difference. It takes 3 command line parameters - FIFO name (will be created if doesn't exist), number of producers, and number of consumers.
Code:
#include <stdlib.h>
#include <unistd.h>
#include <semaphore.h>
[Code].....
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Jun 19, 2013
I am trying to emulate callback mechanism in C. The code I have is follows:
Code:
#include <stdio.h>
#include <pthread.h>
struct fopen_struct {
char *filename;
char *mode;
void *(*callback) (FILE *);
[Code] .....
If I do a pthread_join in fopen_t() it works perfectly fine. But if I do that in main() I get a segmentation fault error. I want to call it in main() because I want it to be non-blocking, is there any solution?
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Apr 24, 2014
I am doing Histogram using pthreads and after long struggle on it.. finally it says 'Segmentation Fault (Core Dumped)'. I knew that error means something somewhere I am accessing to a wrong memory location.
Here is my code..
#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
void Usage(char prog_name[]);
void Gen_data(void *p);
void Gen_bins(void *p);
int Which_bin(void *p);
void Print_histo(void *p);
[Code] ...
How to fix 'Segmentation Fault (Core Dumped)'?
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Feb 3, 2013
I am creating a program that solves the quadratic equation ax^2 + bx +c.
I have this program almost complete except the output of the equation in the function called display_quadratic. I need the program to display the variables a,b,c in the equation ax^2 + bx + c but I am having 2 problems. My first problem is that I cannot get the right addition and subtraction signs for the equation.
For instance, if the program had the values for a,b,c as 2,2,3
it will display 2x^2 2x 3
How can I get it to display 2x^2 + 2x + 3? or if it was negative like 2x^2 - 2x - 3?
My next question is how do I get to not display the coefficients that are 1?
I had an if-else statement but no matter what I created it would overlap with another statement and print out twice. Here is the code:
Code:
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
void display_quadratic (float a, float b, float c);
float root1(float a, float b, float c);
[Code] ......
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Oct 19, 2012
I need to make a program which solove difference between two interested times in format hh:mm i made it but it doesn't give me right answers for all times for example it can't solve times like 23:50 and 0:15 and it says that difference is 23:35 and no 00:25
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Nov 28, 2013
I try to make dll and install it under "Component Services". I tried to make method that return string but when i test it i don't get any result :
Code:
STDMETHODIMP CSimpleChat::CellMe(BSTR name, BSTR** helloMessage) {
CString temp = _T("Hi ");
temp += name;
temp += ", welcome to the simple chat server!";
BSTR str = temp.AllocSysString();
*helloMessage = &str;
return S_OK;
}
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Jan 17, 2013
I've been trying for more than one month to access a method found in a library called libcocosnas_static.a. I'm using Cocos2d-X version 2.0.4. The library has been used many times by my company to make games using cocos2d-1.0.1-x-0.12.0 without any problem.
This is what I've done:
1- I added the include paths of the library to both eclipse and Android.mk
2- Included the .h file using #include "NASPlatformUtil.h"
3- Added the libcocosnas_static.a file to the proj.androidobjlocalarmeabi folder
4- Added "LOCAL_WHOLE_STATIC_LIBRARIES += cocosnas_static" to the Android.mk file
5- Called the function using: NASPlatformUtil:: openUrl("http://xxx.xxx.com/");
I can right click on the function, click Open Declaration and get it without any problem, but the compiler keeps on giving me that dreaded error...
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May 2, 2013
So using InitiateSystemShutdownEx causes a Win32 machine to go log off go to the shutdown screen and just sit there displaying shutting down with the working indicator just spinning. I left the machine sitting there for an hour and it never shut down. This works fine on all the Win7 x64 machines we are using but the one 32 bit Win7 machine has this problem and it occurs no matter what parameters I pass.
Code:
HANDLE hToken;
TOKEN_PRIVILEGES tkp;
// Get a token for this process.
if (!OpenProcessToken(GetCurrentProcess(),
TOKEN_ADJUST_PRIVILEGES | TOKEN_QUERY, &hToken))
return false ;
// Get the LUID for the shutdown privilege.
LookupPrivilegeValue(NULL, SE_SHUTDOWN_NAME,
&tkp.Privileges[0].Luid);
[code]....
This is working fine on Win7 x64 but not on the one Win7 32 system we have and like I said it starts the shutdown process just never finishes.
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Feb 7, 2013
I want to run Unhidden.exe in drive N: and send char to that program. I use function like this
Code:
system("N:/Unhidden.exe");
It can open Unhidden.exe but it run in visual studio 2010Projects . I try to use command N: and Unhidden.exe in cmd it can run in drive N: . So I try to use function like this
system("N:");
system("Unhidden.exe");
but it not found Unhidden.exe . How to use 2 command in sytem() function ?
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Apr 20, 2012
My task I am trying to accomplish is write a program for C++ that numerically solves a quantum harmonic oscillator. I have a routine that I am trying to implement into this program that iterates through a matrix and finds it eigenvalues, however, I do not know how to put it all together to make it work. Code is below:
Code:
//Compiler flags and numerical constants
#include <iostream>
#include <math.h>
#define L 10.0
#define N 200
using namespace std;
[Code] ....
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May 16, 2013
I am wanting to separate the logic from the visual, but I'm having problems when calling the method that controls the actions of the progress bar timer.
Code:
ifndef PROGRESS_BAR
define PROGRESS_BAR
class Progress_bar{
public:
void set_Progress(ToolStripStatusLabel^ label,Timer^ time){
[Code] ....
The way that I'm calling this method on Form1.h
void set_Progress(toolStripStatusLabel1 ,timer1);
Errors:
Error1error C2182: 'set_Progress' : illegal use of type 'void'h:cry_devprogrammingc++school_mediaschool_mediaForm1.h277
Error2error C2078: too many initializersh:cry_devprogrammingc++school_mediaschool_mediaForm1.h277
Error3error C2440: 'initializing' : cannot convert from 'System::Windows::Forms::Timer ^' to 'int'h:cry_devprogrammingc++school_mediaschool_mediaForm1.h277
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Oct 11, 2013
I have a COM Object created using ATL (without MFC Support)
The Object has 1 method that opens a Dialog (that does all the rest) and when finish - returns 2 values back (1 is enough)
Currently I call it from another EXE:
hr = CoCreateInstance(
CLSID_MyControl,
NULL,
CLSCTX_INPROC_SERVER,
IID_IMyControl,
(void**) &pMyControl
);
and then:
hr = pMyControl->MyMethod (ATL::CComBSTR(InputString1), ATL::CComBSTR(InputString2), &IntReturned, &IntReturned);
Is it possible to call it as is from a browser ?
How can I Instantiate the object and invoke my method (with params) from the browser ?
will it open the dialog ?
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Aug 1, 2013
#include<iostream.h>
#include<conio.h>
class sum {
int a,b,ans;
public:
void geta() {
cin>>a;
[Code] ....
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Oct 11, 2013
I am drawing in a simple (square) MFC window. I realize that (0,0) starts in the upper left hand corner. I wanted to see how MFC handled drawing of angles, so I use this code:
Code:
double CompassDegreesToRadians(double compassDegrees) {
return((PI / 2.0f) - (compassDegrees * PI / 180.0f));
}
// Make pen
CPen penRed;
penRed.CreatePen(PS_SOLID | PS_COSMETIC, 1, RGB(255, 0, 0));
// Test Angles
[Code] .....
Using this code, and changing the value of angle1 to these values (0, 90, 180, 270) I think MFC uses the coordinate system:
Code:
180 -y
|
|
-x 270---------------- 90 +x
|
|
0 +y
This seems like a strange coordinate system to use. Am I doing something wrong? If this is correct, how can I convert my calculations to this coordinate system? (compass degrees):
Code:
0 +y
|
|
-x 270---------------- 90 +x
|
|
180 -y
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Apr 4, 2014
I am struggling to find a replacement of NtQuerySystemInformation call for 64-bit Windows OS, like on Windows Server 2008 (64-bit). Need getting overall CPU utilization (average) over all CPU cores?
Code:
#include "StdAfx.h"
#include "CpuMuninNodePlugin.h"
#define SystemBasicInformation 0
#define SystemPerformanceInformation 2
#define SystemTimeInformation 3
[Code] ....
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Nov 19, 2013
I need to find out all the possible equations which are same of a given equation. For eg. a+b+c-d and b+c+a-d are same. So if the user inputs a+b+c-d then the output will be all the possible equations that can be formed from the given equation, viz:
a+c+b-d
c+a+b-d
-d+a+c+b
etc
i.e the program should rearrange the operands and operators in such a way that it should give the same result.
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Jan 21, 2013
I am getting "driver could not be loaded due to system error 8" error while connecting to SQL Server 2005 from VC++. Its also throwing out of memory error. Basically i am developing and ISAPI dll. I use the following code to connect to DB.
CDatabase DBConnection;
if(! DBConnection.IsOpen()) {
DBConnection.OpenEx("Driver={SQL Server};Server=10.120.110.30;Database=Test;Trusted_Connection=yes;", CDatabase:penReadOnly | CDatabase::noOdbcDialog);
[Code] .....
for CDatabaseConnection, i can see 2 different method to open the connection, OpenEx and Open. Whats the difference between OpenEx and Open?
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Feb 11, 2013
I wish to add the item 'Website' to an MFC Dialog app System Menu so that it can activate the following method:
Code:
void CMyDlg::OnWebpage()
{
ShellExecute( NULL, NULL, _T("[URL]..."), NULL, NULL, 0 );
}// OnWebpage()
I have tried this:
Code:
#define IDM_WEBSITE (WM_USER + 101)
//..
if (!strAboutMenu.IsEmpty())
{
pSysMenu->AppendMenu(MF_SEPARATOR);
pSysMenu->AppendMenu(MF_STRING, IDM_ABOUTBOX, strAboutMenu);
pSysMenu->AppendMenuW(MF_STRING, IDM_WEBSITE, _T("Website"));
}
[Code]...
The code compiles without error but and the 'website' item appears on the System Menu but it doesnt do anything.
I've inspected the following but don't really understand how it works and it seems to me there should be a simpler way to accomplish my end.
Modifying the System Menu By John Simmons 26 Jan 2007 [URL]....
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Apr 29, 2014
I have a very strange problem with the system() function (on XP).
I have the following code:
Code:
char *text1 = ""A SpaceAction.bat" fred";
char *text2 = ""A SpaceAction.bat" "fred"";
int main(int argc, char *argv[]) {
printf("%s
", text1);
[Code] .....
When I run it where "A Space" is a directory with a space in the name, this is the result:
Code:
"A SpaceAction.bat" fred
F:Test>echo Testing
Testing
"A SpaceAction.bat" "fred"
'A' is not recognized as an internal or external command, operable program or batch file.
It seems that the double quotes round an argument make the parsing of the command fail.
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Dec 19, 2012
I need make a CBitmap or a streamdata from a System.Windows.Controls::Image(rendered out put)in a SDI mfc application (supporting clr). Here is my codes:
Code:
using namespace System;
using namespace System::IO;
using namespace System::Collections::Generic;
using namespace System::Windows;
using namespace System::Windows::Controls;
[Code] .....
By this codes i can read datastream from bitmapSource but in this way somthing goes wrong in most of GIF animations. After debug i found out i need 3 more things too decode a gif animation - (x,y) position and size of each frame and disposal method for each one - finally i just found a way to draw tru images on a form window by this codes:
Code:
System::Windows::Window^ mainWindow;
mainWindow = gcnew System::Windows::Window();
mainWindow->Title = "GIF Imaging Sample";
//ScrollViewer^ mySV = gcnew ScrollViewer();
array<System::Byte>^ pixels = gcnew array<System::Byte>(bitmapSource->PixelHeight * Stride);
[Code] ...
When i change
Code: bitmapSource = decoder->Frames[0];
to
Code: bitmapSource = decoder->Frames[01];
frame[1] has drawn perfectly on window(i think some how Image class takes care about - (x,y) position and size of each frame and disposal method for each one ),so im wonder if how can i make a CBitmap or a data stream from System.Windows.Controls::Image class to use in mfc app.
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Aug 17, 2013
Program which accepts two lines and and determines their intersection point and whether they lie within a circle, also given interactively. I'm racing against time and I've racked my skull to no avail
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