 are only two
kinds of legal lvalues,</p>
<ul>
<li>a variable, or</li>
<li>a variable with one or more indices.</li>
</ul>
<p>To be used as an lvalue, an indexed variable must have at least as
many dimensions as the number of indices provided. An array of real
or integer types has as many dimensions as it is declared for. A
matrix has two dimensions and a vector or row vector one dimension;
this also holds for the constrained types, covariance and correlation
matrices and their Cholesky factors and ordered,