Now, you tell me see what we want we want the ship to be stable, what should be the criteria for sigma 1 sigma 2, that is what we have to now look for. Now, no now what we see, now let us take one by one, if sigma 1 is real sigma was imaginary; that means, sigma 1 is now i sigma, then what happens the solution is a sinusoidal then, it goes like that.