What we have seen in linear wave theory is that according to the linear waves, the individual waves eta t 1 is basically is a cos curve – A 1 cosine of K 1 x minus omega i t plus epsilon i; something like that. Now, eta 2 T – take another way, which is another cos curve – A 2 cosine of K 2 x minus omega I t plus epsilon i. Now, the point is that we have seen according to linear theory, sum of these two waves will simply be given by this sum of the two. Why? Because linear theory allows me to superpose waves. You see if for example, this is a solution the for problem phi 1, this is a solution for the problem phi 2, then we find out that basically, phi is a linear, the system is linear as well as… Therefore, phi 1 plus phi 2 can be added, superpose. In other words, what happened, if I add these two up (Refer Slide Time: 05:58), what I get becomes actually as per the linear theory of the wave, which is sum of the two. This is very important, because what it means that it allows me to superpose waves, which therefore, tells me that supposing I can break it down to this (Refer Slide Time: 06:21)? Yes, the every one of them individually would represent a typical regular wave. In other words, I can think therefore, that an irregular wave of this signal is nothing but a sum of regular waves.