</A>

<P>
<B><FONT SIZE="+1">Purpose</FONT></B>
<PRE>
  To reduce 2*nb columns and rows of a real (k+2n)-by-(k+2n)
  matrix H:

          [ op(A)   G   ]
      H = [             ],
          [  Q    op(B) ]

  so that elements in the first nb columns below the k-th
  subdiagonal of the (k+n)-by-n matrix op(A), in the first nb
  columns and rows of the n-by-n matrix Q and in the first nb rows
  above the diagonal of the n-by-(k+n) matrix op(B) are zero.
  The reduction is performed by orthogonal symplectic
 