169 



When applied for two wave components of the same wavelength, same amplitude, 

 and opposing directions, the solution is a standing wave. The resulting solution 

 coincides almost exactly with a standing wave solution given by Chen (1988), except 

 for one coefficient. The authors suggest that the slight discrepancy is the result of a 

 typographical error in Chen's paper. 



Ohyama et al. also indicated that they compared their solution with those for 

 short-crested seas (Hsu 1990; Hsu and Chen 1992; Fenton 1985c) and once again 

 found essentially perfect agreement. 



A. 4 Numerical Verification 



The above theoretical verifications indicate that the method is correct when re- 

 duced to two particular simplifications. It remains to verify that the method is 

 accurate when applied to a more complex situation, with a number of intersecting 

 waves of different heights, directions and wavelengths. 



The actual computation of the general solution is quite complicated and contains 

 a very large number of coefiicients that must be computed. Despite this complexity, 

 once the code is written and debugged, it is a trivial matter for modern computers 

 to calculate the full solution. It is not, however, a trivial matter to write the code 

 without errors or, indeed, to find the likely typographical errors in the published 

 paper. A number of these typographical errors have been presented in the published 

 erratum (Ohyama et al. 1995b). 



An additional error has been found and confirmed by personal communication 

 with the authors, pp. 55 Eq. 47 in Ohyama, Jeng, and Hsu (1995a) should read: 



C = \ 8^(3220 + s:'^f^42o\ cos2kx + e'^/344ocos4kx + l2e + £^(33ii> coskxcosut 



+ \ ^^/5222 + £^^422 f cos 2kx COS 2u:t -t- t^/?3i3 cos kx cos 3ujt 



+e /9331 COS 3kx COS ut + s^/Ssss cos 3kx cos 3ut + e^/5424 cos 2kx cos 4ujt 



+e^/?442 COS 4kx cos 2u)t + £^/?444 COS 4kx cos 4Lijt -\- 0{£^} 



As a result of the complexity of the computational code, it is advisable to use numer- 



