        ( 0  0 )

     F = R,  M &gt;= N,   F = ( 0  Z ),  M &lt; N,  if TRANS = 'C'.
                           ( 0  R )

  The transformed equation is then solved for V, from which U is
  obtained via the QR factorization of V*Q**H, if TRANS = 'N', or
  via the RQ factorization of Q*V, if TRANS = 'C'.

</PRE>
<A name="References"><B><FONT SIZE="+1">References</FONT></B></A>
<PRE>
  [1] Bartels, R.H. and Stewart, G.W.
      Solution of the matrix equation  A'X + XB = C.
      Comm. A.C.M., 15, pp. 820-826,