use <code>arr</code> as a usual
multidimensional array.

     <li>When you are done using the array, deallocate the memory by <code>call
fftw_free(p)</code> on <code>p</code>.

        </ol>

   <p>For example, here is how we would allocate an L&nbsp;&times;&nbsp;M 2d real array:

<pre class="example">       real(C_DOUBLE), pointer :: arr(:,:)
       type(C_PTR) :: p
       p = fftw_alloc_real(int(L * M, C_SIZE_T))
       call c_f_pointer(p, arr, [L,M])
       <em>...use arr and arr(i,j) as usual...</em>
  