 than or equal to TOL(2) are ignored for scaling. If the
          user sets TOL(2) &gt;= 0, then the given value of TOL(2) is
          used. If the user sets TOL(2) &lt; 0, then an implicitly
          computed, default threshold, THRESH, is used instead,
          defined by THRESH = 0.1, if MN/MX &lt; EPS, and otherwise,
          THRESH = MIN( 100*(MN/(EPS**0.25*MX))**0.5, 0.1 ), where
          MX and MN are the maximum and the minimum nonzero absolute
          value, respectively, of the elements of