45 



2lT 



b_(o) = z: \ S(a,9) sin nO dG 

 



(4.17) 



The first seven Fourier coefficients in the Fourier series 

 representation of the directional spectrum. Equation A. 14, (i.e., 

 N=3) , are obtainable from the auto- and cross-spectra, (Equations 4.6 

 through 4.13) : 



^0 = 27^n(") 



(4.18) 



^ = Z-1. S (a) 

 1 iTTk nn 



(4.19) 



1^ = — TT [S (a) - S (a)] 



2 2 n n n n 



TTK XX y y 



(4.20) 



, 4- k S (a) + S (a 



3 .34 nn n n 



ITTk ■- X X XX - 



(4.21) 



b, = ^ [S (a)i 



1 mk nn 

 y 



(4.22) 



