nces</B>
<PRE>
  TOL     DOUBLE PRECISION
          The tolerance to be used in determining the
          controllability of a single-input system (A,b) or (A',c'),
          where b and c' are columns in B and C' (C transposed). If
          the user sets TOL &gt; 0, then the given value of TOL is used
          as an absolute tolerance; elements with absolute value
          less than TOL are considered neglijible. If the user sets
          TOL &lt;= 0, then an implicitly computed, default tolerance,
   