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Ocean Color Science Software

ocssw V2022
angles.f
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1  SUBROUTINE angles(M,A,B,CN,SN,TN)
2 C VERSION OF 4/2/87
3 C PURPOSE
4 C COMPUTES COS(M*A), SIN(M*A), M*TAN(B) AND STORE VALUES IN
5 C ARRAYS CN, SN, TN
6 C INPUT
7 C M = ORDER OF SPHERICAL HARMONICS TO BE EVALUATED
8 C A = LONGITUDE FROM GREENWICH (RAD)
9 C B = LATITUDE (RAD)
10 C OUTPUT
11 C CN = M-D ARRAY OF COS VALUES
12 C SN = M-D ARRAY OF SIN VALUES
13 C TN = M-D ARRAY OF TAN VALUES
14 C CALLED BY SUBROUTINES
15 C DER
16 C CALL SUBROUTINES
17 C NONE
18 C REFERENCES
19 C JPL EM 312/87-153, 20 APRIL 1987
20 C ANALYSIS
21 C J. H. KWOK - JPL
22 C PROGRAMMER
23 C J. H. KWOK - JPL
24 C PROGRAM MODIFICATIONS
25 C NONE
26 C COMMENTS
27 C
28  IMPLICIT DOUBLE PRECISION (a-h,o-z)
29  dimension cn(41),sn(41),tn(41)
30  DATA zero,one,two/0.d0,1.d0,2.d0/
31  cn(1)=one
32  sn(1)=zero
33  tn(1)=zero
34  IF (m.EQ.0) RETURN
35  cn(2)=dcos(a)
36  sn(2)=dsin(a)
37  tn(2)=dtan(b)
38  IF (m.EQ.1) RETURN
39  DO 100 i=2,m
40  cn(i+1)=two*cn(2)*cn(i)-cn(i-1)
41  sn(i+1)=two*cn(2)*sn(i)-sn(i-1)
42  100 tn(i+1)=tn(2)+tn(i)
43  RETURN
44  END
45