使用fftw库时C ++代码无法运行

Question

I am trying to implement a DFT using the fftw library ( link to FFTW documentation ).

All the libraries have been correctly linked, and the project builds just fine. However, the code doesn't run the moment any function from the fftw library is called.

#include <iostream>
#include <fftw3.h>

using namespace std;

int main() {

    int vectorSize = 100;
    cout << vectorSize << endl;

    fftw_complex vec[vectorSize], vecOut[vectorSize];

    for(int i = 0; i < vectorSize; i++) {
        vec[i][0] = i;
        vec[i][1] = 1;
    }

    // Call to function to create an FFT plan
    fftw_plan plan = fftw_plan_dft_1d(vectorSize, vec, vecOut, FFTW_FORWARD, FFTW_ESTIMATE);

    cout << "test" << endl;

    return 0;
}

If I comment the line where the fftw_plan is instantiated, the code outputs 100 and "test" as expected. There are no issues in the build, as far as I can tell. I haven't really been able to find any post which describes a similar problem.

I am running this on eclipse, using MinGW and the 32 bit version of the pre-compiled binary available for windows ( download link ).

Any help would be really appreciated :)

Answer 1

Fftw requires input/output to be 16-byte aligned. When you declare the arrays on stack, this can't be guaranteed. So you need to call fftw_malloc or other function to allocate the arrays. Also, your code only creates the plan but doesn't execute it, thus no fft is carried out on the input data.