Projective synchronization, in which the state vectors synchronize up to a
scaling factor, has recently been observed in coupled partially linear chao
tic systems (Lorenz system) under certain conditions. In this Letter, we pr
esent a stability criterion that guarantees the occurrence of the projectiv
e synchronization in three-dimensional systems. By applying the criterion t
o two typical partially linear systems (Lorenz and disk dynamo), it shows t
hat only some parameters play the key role in influencing the stability. Pr
ojective synchronization only happens when sigma > -1 for the Lorenz and mu
> 0 for the disk dynamo. (C) 2001 Elsevier Science B.V. All rights reserve
d.