code: def integrate(self,t,pot,method='odeint',dt=None):
          
          if hasattr(self,'_orbInterp'): delattr(self,'_orbInterp')
          self.t= nu.array(t)
          self._pot= pot
          self.orbit= _integrateLinearOrbit(self.vxvv,pot,t,method,dt)
docs: NAME:
             integrate
          PURPOSE:
             integrate the orbit
          INPUT:
             t - list of times at which to output (0 has to be in this!)
             pot - potential instance or list of instances
             method= 'odeint'= scipy's odeint, or 'leapfrog'
             dt= (None) if set, force the integrator to use this basic stepsize; must be an integer divisor of output stepsize (NOT USED FOR LINEAR ORBIT SO FAR)
          OUTPUT:
             (none) (get the actual orbit using getOrbit()
          HISTORY:
             2010-07-13 - Written - Bovy (NYU)