Hi all,

I am running into a problem which can be best descrivbed as below:

I have a QT4 C++ program which calls a matlab created library (compiled with MSVC2008). I am using MSVC2008 as IDE on Windows XP and the program is being compiled with MSVC2008 as well. I followed all the instructions regarding the dll compilation and how to integrate it to my code (MCR installation, etc.). Now, I could compiled and run it but got nothing from the MATLAB routine. The following is the key code.
Qt Code: 
  1. DisplayWidget::DisplayWidget(QWidget *parent)
  2. 	: QWidget(parent)
  3. 	, pointsPerBlock(6400)
  4. {
  5. 	QString titleText;
  6. 	ui = new Ui::DisplayWidget();
  7. 	ui->setupUi(this);
  8.  
  9.        ...
  10.         [COLOR="#FF0000"]
  11.         // I Initialize the mcl application and lib in the constructor
  12.         [/COLOR]
  13. 	if (!mclInitializeApplication(NULL,0))
  14. 	{
  15. 		qDebug() << "Fail to initialize application!";
  16. 		return;
  17. 	}
  18. 	if (!libpulseanalysisInitialize())
  19. 	{
  20. 		qDebug() << "Fail to initialize library!";
  21. 		return;
  22. 	}
  23.  
  24.         ...
  25. }
  26.  
  27. DisplayWidget::~DisplayWidget()
  28. {
  29.         [COLOR="#FF0000"]
  30.         // Terminate application and lib in destroyer
  31.         [/COLOR]
  32. 	libpulseanalysisTerminate();
  33. 	mclTerminateApplication();
  34. 	delete ui;
  35. }
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I tried to call the matlab routine in a slot function
Qt Code: 
  1. void DisplayWidget::analyseData(void)
  2. {
  3. 	QRectF rect(d_display->getZoomerRect());
  4. 	//qDebug() << static_cast<int>(rect.left());
  5. 	//qDebug() << static_cast<int>(rect.width());
  6.     QByteArray data(d_data.mid(static_cast<int>(rect.left()),
  7.         static_cast<int>(rect.width()) * sizeof(double))); 
  8. 	qDebug() << data.size();
  9. 	int dataLength = data.size();
  10. 	qDebug() << dataLength;
  11.     QDataStream dataStream(&data, QIODevice::ReadOnly);
  12.     dataStream.setByteOrder(QDataStream::ByteOrder(QDataStream::LittleEndian));
  13.     dataStream.setFloatingPointPrecision(QDataStream::DoublePrecision);
  14.     double *pData = new double(dataLength);
  15.     for (int i = 0; i < dataLength; i++)
  16.     {
  17.         dataStream >> *(pData + i);
  18.     }
  19.     int downSamplingFactor = 5;
  20.     int windowWidth = 500;
  21.  
  22. 	//mxArray *sig = NULL;
  23. 	//mxArray *downsampling_factor = NULL;
  24. 	//mxArray *window_width = NULL;
  25.  
  26.  
  27. 	//sig = mxCreateDoubleMatrix(1, dataLength, mxREAL);
  28. 	//memcpy(mxGetPr(sig), pData, sizeof(double) * dataLength);
  29.  
  30. 	//downsampling_factor = mxCreateNumericMatrix(1, 1, mxINT32_CLASS, mxREAL);
  31. 	//memcpy(mxGetPr(downsampling_factor), &downSamplingFactor, sizeof(double));
  32.  
  33. 	//window_width = mxCreateNumericMatrix(1, 1, mxINT32_CLASS, mxREAL);
  34. 	//memcpy(mxGetPr(window_width), &window_width, sizeof(double));
  35.  
  36. 	mwArray sig(1, dataLength, mxDOUBLE_CLASS);
  37. 	sig.SetData(pData, dataLength);
  38. 	mwArray downsampling_factor(1, 1, mxINT32_CLASS);
  39. 	downsampling_factor.SetData(&downSamplingFactor, 1);
  40. 	mwArray window_width(1, 1, mxINT32_CLASS);
  41. 	window_width.SetData(&windowWidth, 1);
  42. 	mwArray edge_time;
  43.  
  44. 	pulse_analysis(1, edge_time, sig, downsampling_factor, window_width);
  45.  
  46. 	qDebug() << edge_time.ElementSize();
  47.  
  48. 	//int r = mxGetM(edge_time);
  49. 	//int c = mxGetN(edge_time);
  50.  
  51. 	//qDebug() << r;
  52. 	//qDebug() << c;
  53. }
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I placed a break point on the pulse_analysis function. After the program reached the break point, I press the F10, then the program enter into the
Qt Code: 
  1. QHashData::Node *QHashData::nextNode(Node *node)
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and stopped on the following instruction.
Qt Code: 
  1. int start = (node->h % d->numBuckets) + 1;
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The content in the output window is:
First-chance exception at 0x670a539d (QtCored4.dll) in XXXX.exe: 0xC0000094: Integer division by zero.
Unhandled exception at 0x670a539d (QtCored4.dll) in XXXX.exe: 0xC0000094: Integer division by zero.
I didn't know why the application throw this error message. I wanted to investigate where the error come from, but I didn't know how to debug such an application. Could anybody give me some help?