does reduce
the vector dimension (to a scalar), so the result type for <code>w</code> is
an array of reals. In both cases, the size of the multiple index
(here, 7) determines the size of the result.</p>
</div>
<div id="matrices-1" class="section level3">
<h3 class="unnumbered" number="">Matrices</h3>
<p>Matrices are a bit trickier because they have two dimensions, but the
underlying principle of type inference is the same—multiple indexes
leave dimensions in place, whereas single indexes reduce them. The
