These are the equations I am talking about when time permits, you have to sit and derive yourself sufficiently large number of k enables application of central limit theorem to equation 16 and 17 stating that if n is large the waves follow Gaussian distribution are the wave elevation is normally distributed it follows a normal distribution or we say that the wave is a waves are a Gaussian process. Since epsilon suffix are m comma n is uniformly distributed between 0 to 2 pi, that means 0 and 2 pi as stated earlier. We have been seeing this from the beginning from our random 2 D waves and now C m and S m will follow will have a zero mean the variances can automatically be proved to be as a product of frequency interval and vector density in fact we have done this for 2 D waves. Please look at the lecture on two D random waves wherein we have done this.