  Some memristors are quite interesting from the point of view of dynamical
systems. When driven by narrow pulses of alternating polarities, their dynamics
has a stable fixed point, which may be useful for future applications. We study
the transient dynamics of two types of memristors characterized by a stable
fixed point using a time-averaged evolution equation. Time-averaged
trajectories of the Biolek window function memristor and resistor-threshold
type memristor circuit (an effective memristor) are determined analytically,
and the times of relaxation to the stable fixed point are found. Our analytical
results are in perfect agreement with the results of numerical simulations.
