 each individual dimension should be able to
operate in place.)
<a name="index-in_002dplace-6"></a>
</p>

<p><code>in</code> and <code>out</code> point to the input and output arrays for r2c
and c2r transforms, respectively.  For split arrays, <code>ri</code> and
<code>ii</code> point to the real and imaginary input arrays for a c2r
transform, and <code>ro</code> and <code>io</code> point to the real and imaginary
output arrays for an r2c transform.  <code>in</code> and <code>ro</code> or
<code>ri</code> an