al_002dto_002dReal-Transforms-1"></span><h4 class="subsection">4.3.5 Real-to-Real Transforms</h4>
<span id="index-r2r-1"></span>

<div class="example">
<pre class="example">fftw_plan fftw_plan_r2r_1d(int n, double *in, double *out,
                           fftw_r2r_kind kind, unsigned flags);
fftw_plan fftw_plan_r2r_2d(int n0, int n1, double *in, double *out,
                           fftw_r2r_kind kind0, fftw_r2r_kind kind1,
                           unsigned flags);
fftw_plan fftw_plan_r2r_3d(int n0, 