We have learned that if the poles of a system are in the left half of the s plane, the system is stable (i.

We have learned that if the poles of a system are in the left half of the s plane, the system is stable (i.e., the impulse response of the system is either a decaying exponential or a decaying sinusoid). Also, if poles are in the right half of s plane, the impulse response is a growing exponential or sinusoid. What is the waveform of the impulse response if a complex pair of two poles of a system are exactly on the imaginary or jω axis or the dividing line of the left and right half plane? What happens if the poles are on this dividing line and exactly on the origin of the s plane?