Topic/default/fix issue36
Please check that arr_coarse is created in spectral space with the right shape (cf. https://fluidfft.readthedocs.io/en/latest/ipynb/executed/tuto_fft3d_mpi_domain_decomp.html#summary)
Please check that arr_coarse is created in spectral space with the right shape (cf. https://fluidfft.readthedocs.io/en/latest/ipynb/executed/tuto_fft3d_mpi_domain_decomp.html#summary)