und.
<P>
This function can be invoked after the dense problem has been solved,
to get the residual norm estimate of the associated Ritz pair. In that
case, the relevant information is returned in rnorm.
<P>
For computing eigenvectors, LAPACK's _trevc is used so the matrix must
be in (quasi-)triangular form, or call <A HREF="../DS/DSSolve.html#DSSolve">DSSolve</A>() first.
<P>

<P>
<H3><FONT COLOR="#883300">See Also</FONT></H3>
 <A HREF="../DS/DSSolve.html#DSSolve">DSSolve</A>()
<BR><P><B><FONT COLOR="#88330