ension of array X.  LDX &gt;= MAX(1,N).

</PRE>
<B>Workspace</B>
<PRE>
  DWORK   DOUBLE PRECISION array, dimension (LDWORK)
          On exit, if INFO = 0, the leading M-by-N part of this
          array (with the leading dimension MAX(1,M)) returns the
          matrix product beta*op( A )*T, where T is the triangular
          matrix defined in the Method section.
          This array is not referenced when beta = 0.

  LDWORK  The length of the array DWORK.
          LDWORK &gt;= MAX(1,M*N), if  beta &lt