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Output inside function mismatches outside function

JamieAl (236)
Why does my function returns zeros when called in a script but then if I try to print out the output "inside" the function I get the correct results? I am confused!

For example, here's an FFT function I wrote, where the print statements return correct results:
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void r2cfft3d(Eigen::Tensor<double, 3>& rArr, Eigen::Tensor<std::complex<double>, 3> cArr){	
fftw_complex *input_array;
fftw_complex *output_array;

input_array = (fftw_complex*) fftw_malloc(nx*ny*nz * sizeof(fftw_complex));
output_array = (fftw_complex*) fftw_malloc(nx*ny*nz * sizeof(fftw_complex));


for (int i = 0; i < nx; ++i) {

        for (int j = 0; j < ny; ++j) {

            for (int k = 0; k < nz; ++k) {
                {
                    input_array[k + nz * (j + ny * i)][REAL] = rArr(k,i,j);
                    input_array[k + nz * (j + ny * i)][IMAG] = 0;
                }
            }
        }
    }
fftw_plan forward = fftw_plan_dft_3d(nx, ny, nz, input_array, output_array, FFTW_FORWARD, FFTW_ESTIMATE);
fftw_execute(forward);
fftw_destroy_plan(forward);
fftw_cleanup();

     for(int i=0; i < nx; ++i){

        for(int j=0; j < ny; ++j) {

            for(int k=0; k < nz; ++k) {
                cArr(k,i,j).real(output_array[k + nz * (j + ny * i)][REAL]);
                cArr(k,i,j).imag(output_array[k + nz * (j + ny * i)][IMAG]);
                
     }

   }
}
std::cout<<cArr<<endl; //this is correct
	
fftw_free(input_array);
fftw_free(output_array);

}

Then when I call this function in a separate script:
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Eigen::Tensor<double, 3> uFun(nx,ny,nz); 
uFun.setZero(); 
	
for(int i = 0; i< nx; i++){
	for(int j = 0; j< ny; j++){
		for(int k = 0; k< nz; k++){ 
			uFun(k,i,j) = sin(3. * A * eZZ(k,i,j)) * sin(A * eXX(k,i,j)) * cos(A1 * eYY(k,i,j));
                
    }
  }		
}
Eigen::Tensor<std::complex<double>, 3> Test(nx,ny,nz);  
Test.setZero();
r2cfft3d(ne,Test);
std::cout<<Test<<endl; //ZEROS!
Last edited on
JLBorges (13770)
Pass it by reference (to non-cost).
JamieAl (236)
@JLBorges
oh I see. Thanks!
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