;&gt; 0;
          LDWORK &gt;= 1,          if  beta =  0.

</PRE>
<B>Error Indicator</B>
<PRE>
  INFO    INTEGER
          = 0:  successful exit;
          &lt; 0:  if INFO = -k, the k-th argument had an illegal
                value.

</PRE>
<A name="Method"><B><FONT SIZE="+1">Method</FONT></B></A>
<PRE>
  The matrix expression is efficiently evaluated taking the symmetry
  into account. Specifically, let X = T + T', with T an upper or
  lower triangular matrix, defined by

     T = triu( X ) - (1/2)*diag