61 



other two (also separated by 180'^) are associated with minima and 

 separated from the first two roots by 90°. Two of these roots can be 



m 



OJ 



c 



(D 

 •P 



J\ iJ U U 1 



'IJ /^5 |3tr y^Tt IsTf /^|3Tr iTrr /^ '"' 



14 X |i I4 X 1 |4 X |2 ;t/ 



FIGURE lV-4: Four roots of tangent (29) 



eliminated by considering the signs of the numerator and denominator. 

 The remaining two might be resolved by considering the physical 

 environment of the deployment site. One does not expect, for 

 example, incident swell to approach a straight shoreline at angles 

 much greater than 45 degrees to the shore normal. This directional 

 estimate is calculated in the software package and displayed 

 optional ly. 



