Compilare: main.cpp: In function 'std::vector<std::complex<double> > fft_inv(std::vector<std::complex<double> >&)': main.cpp:97:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0;i<x.size();i++) ~^~~~~~~~~ main.cpp: In function 'int main()': main.cpp:108:31: warning: ignoring return value of 'int fscanf(FILE*, const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] fscanf (fin,"%d%d",&n,&ki); ^ main.cpp:112:29: warning: ignoring return value of 'int fscanf(FILE*, const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] fscanf (fin,"%d",&x); ^ main.cpp:175:25: warning: ignoring return value of 'int fscanf(FILE*, const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] fscanf (fin,"%d",&q); ^ main.cpp:177:29: warning: ignoring return value of 'int fscanf(FILE*, const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] fscanf (fin,"%d",&x); ^