ce approximation.
    </p>

    <p>
      In particular, if we choose a fixed time step size DT, then a derivative
      such as dPREY/dT is approximated by:
      <pre>
        d PREY / dT = approximately ( PREY(T+DT) - PREY(T) ) / DT
      </pre>
      which means that the first differential equation can be written as
      <pre>
        PREY(T+DT) = PREY(T) + DT * ( 2 * PREY(T) - 0.001 * PREY(T) * PRED(T) ).
      </pre>
    </p>

    <p>
      We can rewrite the equation for PRED as well.  Then, since w