Problem casting STL complex to fftw_complex

Question

The FFTW manual says that its fftw_complex type is bit compatible to std::complex class in STL. But that doesn\'t work for me:

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Answer 1

The idea behind bit-compatibility of fftw_complex and C99 and C++ complex types is not that they can be easily created from one another, but that all functions in FFTW that take pointers to fftw_complex can also take pointers to c++ std::complex. Therefore the best approach is probably to use std::complex<> throughout your program and only convert pointers to these values when calling FFTW functions:

std::vector > a1, a2;
....
....
fftw_plan_dft(N, reinterpret_cast(&a1[0]),
                 reinterpret_cast(&a2[0]),
                 FFTW_FORWARD, FFTW_ESTIMATE);
....