the truncated distribution is given by 



g(x)= 



2X e 



X /E 



dx 



for' 



min. /E ^ 



'min. 



< X <00- 



(21) 



The percent of the low waves omitted simply equals 



100 ( l-e " 4 min./E ) 



(22) 



The average amplitude of all of the waves that are higher than 



e is given by the first moment of equation (21), and the evaluation 



of the' integral yields the following result for ^ * which is defined to 



be the average amplitude of all waves in excess of f 



^ ^ "^ mm. 



-* /'CO „ 2 - xVE _, 



2 x^e dx - xe 



x-l 



xVe 



i E(l-e' "^"li"/^) l-e'^f"'"/ 



min. 



00 



/ 



00 



mm. 



xVE 



i . ^min. '-e 



^minA 



mia J 



e dx 



(23) 



*» min. 



[l-e'Cmin.A] 



The last integral inequation (23) is the integral of the normal distribution 

 between known limits. It can easily be evaluated from tables. 



Equation (23) is a function of three variables, ^ *, ^ min., and E. 

 Any tw^o determine the third. Suppose then that the heights of all waves 

 greater than 4 feet are recorded, and that the significant height of the 

 waves is 8 feet. The significant height determines E, and then ^ * 

 can be computed. Under these conditions the average height of all waves 

 greater than 4 feet is 6.64 feet. The percent of waves omitted can be 

 found from (22) and in this case it equals 39.4 percent. 



22 



