- 215 - 



21050 

 2 1 100 

 2 1 150 

 2 1200 

 21250 

 2 1300 

 2 1350 

 2 1400 

 2 1450 

 21500 

 21550 

 2 1600 

 2 1650 

 2 1700 

 2 1750 

 21800 

 21850 

 2 1900 

 21950 

 22000 

 22050 

 22100 

 22150 

 22200 

 22250 

 22300 

 22350 

 22400 

 22450 

 22500 

 22550 

 2 2 GOO 

 22650 

 22700 

 22750 

 22800 

 22850 

 22900 

 22950 

 23000 

 23050 

 23100 

 23150 

 23200 

 23250 

 23300 

 23350 

 23400 

 23450 

 23500 

 23550 

 23600 

 23650 

 23700 

 23750 

 23800 

 23850 

 23900 

 23950 

 24000 



twopi = 6.283185 

 N2 = N/2 



DATA sumabk , sum 1 k , sunn2k .sum3k,sum4k.sabsk.s1k,s2k, 

 s3k,s4k/0. .0.,0..0..0..0..0.,0.,0..0./ 



DO 420 J=2 

 SUMABK 

 SUM1K = sum 1k 

 SUM2K 

 SUM3K 

 SUM4K 

 5ABSK 

 S1K = 



icut 

 sumabk + ab( j ) 



d1(j) 

 cl2(j) 

 d3(j ) 

 d4( j) 

 AB(j: 



= sum2k 



= sum3k 



= SUM4K 



= SABSK + AB(j) * freq(j) 



sik + d1( j ) * freq( j ) 

 32K = s2k + d2U) * freq(j) 

 S3K = s3K + d3(j) + freq(j) 



s4k + d4( j ) * f req( j ) 



S4K = 

 Cont i nue 



Tabsk = twopi * sumabk/sabsk 

 T1k = twopi * sum1k/s1k 

 T2k = twopi * sum2k/s2k 

 T3k = twopi * sum3k/s3k 

 T4k = twopi * sura4k/s4k 



Report the effective period from the absolute gage. 

 WRITE(4,929) Tabsk 

 929 Format(' Effective period =',f7.3.' seconds.') 



Return 

 End 



SUBROUTINE SURF ( icut , d1 , d2 . d3 . d4 , dpi , dp2 . dp3 . dp4 , 



1 d1 i ,d2i ,d3i .d4i ,dir1 ,dir2,dir3,dir4,bik. 



2 orient) 



DIMENSION d1(2050) .d2(2050) .d3(2050), 

 1 d4(2050) 



DIMENSION dpi (4 100) ,dp2(4 100) ,dp3(4 100) ,dp4(4 100) . 

 1 d 1 i ( 205O ) , d2 i ( 2050 ) , d3 i ( 2050 ) , d4 i ( 2050 ) 



DIMENSION dir1(400) ,dir2(400) ,dir3(400) ,dir4(400) 



INTEGER bik 



C Generates directional estimate without absolute gage. 

 C DIR1 uses gages DPI and DP2; 

 C DIR2 uses gages DP3 and DP4; 

 C DIR3 uses gages DP2 and DP3; 

 C DIR4 uses gages DPI and DP4 . 



DO 435 d=2, icut 



if (dpK j ) .ne.0.0)tan1=atan2(d1 i(j ).dp1(J )) 



if (dpK j ) .eq.O. )tan1 = 0.0 



1 f ( dp2 ( J ) . ne , . ) t an2 = a t an2 ( d2 1 ( j ) . dp2 ( j ) ) 



if (dp2( j ) .eq.O. )tan2 =0.0 



if (dp3(J ) .ne.0.0)tan3 =atan2(d3i(j ),dp3(J )) 



if (dp3( J ) .sq.O. )tan3 = 0.0 



