t">
y =

     9
     9
     9

</pre><p>We can also multiply by the adjoint of an operator:</p><pre class="codeinput">w = [1;2;3];
z = C'*w;
</pre><h2>Subset Assignment and Reference<a name="7"></a></h2><p>If we are only interested in applying part of an operator, we can create a new operator that is a restriction of the existing one. The indexing used is the same as in MATLAB matrices; we can specify rows, columns, or individual elements, we can extract rows or columns in reverse, and we can repeat entries