ss="comment">% Initialize last search step</span>
            <span class="comment">% (large negative value to call searchAll in the 1st step)</span>
            this.last_search = -inf;

            <span class="comment">% Set update frequency</span>
            <span class="keyword">if</span> (this.auto_freq)
                vmax = max(vecnorm([drv.particles.veloc_trl]));
                rmax = max([drv.particles.radius]);
                <span class="keyword">if</span> (vmax == 0)
                    thi