4.4.3 Advanced Real-to-real Transforms

fftw_plan fftw_plan_many_r2r(int rank, const int *n, int howmany,
                             double *in, const int *inembed,
                             int istride, int idist,
                             double *out, const int *onembed,
                             int ostride, int odist,
                             const fftw_r2r_kind *kind, unsigned flags);

Like fftw_plan_many_dft, this functions adds howmany, nembed, stride, and dist parameters to the fftw_plan_r2r function, but otherwise behave the same as the basic interface. The interpretation of those additional parameters are the same as for fftw_plan_many_dft. (Of course, the stride and dist parameters are now in units of double, not fftw_complex.)

Arrays n, inembed, onembed, and kind are not used after this function returns. You can safely free or reuse them.