>
<A HREF ="#Example"><B>[Example]</B></A>

<P>
<B><FONT SIZE="+1">Purpose</FONT></B>
<PRE>
  To solve for X the continuous-time Sylvester equation

     AX + XB = C,

  with at least one of the matrices A or B in Schur form and the
  other in Hessenberg or Schur form (both either upper or lower);
  A, B, C and X are N-by-N, M-by-M, N-by-M, and N-by-M matrices,
  respectively.

</PRE>
<A name="Specification"><B><FONT SIZE="+1">Specification</FONT></B></A>
<PRE>
      SUBROUTINE SB04ND( ABSCHU, ULA, ULB, N, 