can you iterate a change in odefun for ode45?

Hi, so I am wanting to plot how a solution to a set of coupled odes change as the function changes by some iterated amount. I have something like this so far:

      for ip = 1:length(phi)
          for it = 1:n        
                phii = phi(ip);
                tt = timerangei(it); %defining the integration time start.
                %ttt = timeranger(it);        
                [t,x] = ode45('Et_Field_ODE45_w2w_phiscan',tt:0.001*1e-15:tf,[0,0],phii);  %solving the coupled odes.
                allx{ip,it,1} = x(:,1);                %assigning the traj to cell
                allv{ip,it,1} = x(:,2);                %assigning the velo to cell
                allt{ip,it,1} = t;                     %assigning the time to cell

          end
      end

So as you can see I am changing the time between tt and tf, but also wanting do that for an iterative change of the phase, phi. Is this something you can do or am I looking at a manual job? At the moment, I thought I'd be able to insert the value of phi, but the way ode45 works it reads phii as an option...

Thanks