Question

I am performing a project with ITK for processing medical images. After a lot of work there is no further compilation errors, but in the linking process I am having the following info :

1>——Generation started: proyect: prueba_r01, configuration: Debug Win32 ——
1>Linking…
1>Creating library C:\Documents and Settings\GTTS\Mis documentos\Visual Studio 2008\Projects\prueba_r01\Debug\prueba_r01.lib and object C:\Documents and Settings\GTTS\Mis documentos\Visual Studio 2008\Projects\prueba_r01\Debug\prueba_r01.exp

1>prueba_r01.obj : error LNK2019: extern symbol "public: double (* __thiscall prueba_r01::multiply_matrix_2D(double ()[2],double ()[2],int,int))[2]" (?multiply_matrix_2D@prueba_r01@@QAEPAY01NPAY01N0HH@Z) unresolved which is referenced in the function "private: void __thiscall prueba_r01::filtro(void)" (?filtro@prueba_r01@@AAEXXZ)

1>C:\Documents and Settings\GTTS\Mis documentos\Visual Studio 2008\Projects\prueba_r01\Debug\prueba_r01.exe : fatal error LNK1120: 1 externos sin resolver

1>prueba_r01 – 2 errors, 0 warnings
========== Generar: 0 corrects, 1 incorrects, 0 actualized, 0 omited ==========

The method multiply_matrix_2D produces the error when is called inside the private slot “filtro()” (translated as filter)
The header of the file is :

#include <QtGui/QMainWindow>
#include "ui_prueba_r01.h"
#include "vicdef.h"
#include "itkImage.h"
#include "math.h"
#include <complex>
#include "fftw3.h"
using namespace std;

#define PI 3.14159265

class prueba_r01 : public QMainWindow
{
Q_OBJECT

public:
typedef double PixelType;
typedef itk::Image < PixelType, 2> ImageType;
    ImageType::Pointer imagen;

double** H;

prueba_r01(QWidget *parent = 0, Qt::WFlags flags = 0);
~prueba_r01();

void matrix2D_H(int ancho, int alto, double eta, double sigma);
fftw_complex* multiply_matrix_2D(fftw_complex* out, fftw_complex* H,int a, int b);

private slots:
void openRGB();
void filtro();


private:
Ui::prueba_r01Class ui;
};

#endif // PRUEBA_R01_H

And the main part where the problem is located is in the .cpp file and is displayed here:

fftw_complex* res ;
res = (fftw_complex*) fftw_malloc(sizeof(fftw_complex)*a*b);
fftw_complex* H_casted= reinterpret_cast<fftw_complex*> (&H);
res = multiply_matrix_2D(out,H_casted, a, b);

The process of casting a **double pointer to *fftw_complex is done here, because I want to multiply a filter in frequency domain (H(w)) with the result of the fft transform of an image, that’s the reason. Is important to remark that fftw_complex is double[2], the first row for the real part, and the second for the imaginary
And the problematic method is shown below:

 fftw_complex* multiply_matrix_2D(fftw_complex* out, fftw_complex* H, int a ,int b){
/* The matrix out[axb] or [n0x(n1/2)+1] is the image after the FFT , and the           out_H[axb] is the filter in the frequency domain,
both are multiplied POINT TO POINT, it has to be called  twice, one for the imaginary part and another for the normal part
*/
 fftw_complex *res;
 res = (fftw_complex*) fftw_malloc(sizeof(fftw_complex)*a*b);
 for (int i0 = 0; i0<a ; i0++){
for (int i1 = 0; i1<b ; i1++){
 res[i1+a*i0][0] = out[i1+a*i0][0]*(H[0][0]+H[0][1]); // real part          
 res[i1+a*i0][1] = out[i1+a*i0][1]*(H[0][0]+H[0][1]); // imaginary part
    }
 }
 return res;
 }

Any help will be really nice!! I’m quite lost now…
Thanks! Gracias!
Antonio

Answer 1

Change the function header in the cpp file to:

fftw_complex* prueba_r01::multiply_matrix_2D(fftw_complex* out, fftw_complex* H, int a, int b) 

You forgot the class name (prueba_r01::) in the implementation, therefore it doesn’t find the function body