(9) Frequency-by-frequency modification of wave angles is made 

 assuming linear wave theory, Snell's law, and parallel bottom con- 

 tours offshore. The breaking wave angle, 0, (n) , is calculated from 



C b (n) sin 9 r (n) 



0. (n) = arcsin 



where the subscript r refers to the reference gage location. 



(10) Longshore energy flux is calculated for each frequency 

 component (except the special cases discussed in Sec. II) using the 

 equation 



P £s (n) = y|F n (n)| 2 C gb (n) sin 2© b (n) 



and is summed up to obtain a net longshore energy flux. 



(11) The value of the net longshore energy flux is multiplied by 

 a factor R which scales up the total energy in the spectrum (below 

 the high frequency cutoff) . The equation for scaling factor R is 



R- l 



(1 - RTOT) 



where RTOT = RSODD + RSHFRQ when RSODD is the percent of energy in 

 low frequency bands for which impossible values of the cosine func- 

 tion are calculated, and RSHFRQ is the percent of energy between 

 spacial aliasing frequency and high frequency cutoff. 



The final result of analysis of the two gage records for the 

 net longshore energy flux PLNET is printed out, as well as specific 

 frequencies for which impossible directional results occur and fre- 

 quencies at which more than 2.5 percent of the total wave energy is 

 found . 



IV. SUBROUTINE DOCUMENTATION 



1. FFT Subroutine. 



The sampled time function, f(j), will be expressed as 



N-l 

 f(j) = I F(n) exp(inaJ 1 JAt) 

 n=o 



22 



