WSJT-X/lib/dcoord.f90
Joe Taylor a9d44f21ce One more
git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@3841 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
2014-03-05 20:19:38 +00:00

41 lines
1.1 KiB
Fortran

SUBROUTINE DCOORD(A0,B0,AP,BP,A1,B1,A2,B2)
implicit real*8 (a-h,o-z)
! Examples:
! 1. From ha,dec to az,el:
! call coord(pi,pio2-lat,0.,lat,ha,dec,az,el)
! 2. From az,el to ha,dec:
! call coord(pi,pio2-lat,0.,lat,az,el,ha,dec)
! 3. From ra,dec to l,b
! call coord(4.635594495,-0.504691042,3.355395488,0.478220215,
! ra,dec,l,b)
! 4. From l,b to ra,dec
! call coord(1.705981071d0,-1.050357016d0,2.146800277d0,
! 0.478220215d0,l,b,ra,dec)
! 5. From ecliptic latitude (eb) and longitude (el) to ra, dec:
! call coord(0.d0,0.d0,-pio2,pio2-23.443*pi/180,ra,dec,el,eb)
SB0=sin(B0)
CB0=cos(B0)
SBP=sin(BP)
CBP=cos(BP)
SB1=sin(B1)
CB1=cos(B1)
SB2=SBP*SB1 + CBP*CB1*cos(AP-A1)
CB2=SQRT(1.D0-SB2**2)
B2=atan(SB2/CB2)
SAA=sin(AP-A1)*CB1/CB2
CAA=(SB1-SB2*SBP)/(CB2*CBP)
CBB=SB0/CBP
SBB=sin(AP-A0)*CB0
SA2=SAA*CBB-CAA*SBB
CA2=CAA*CBB+SAA*SBB
TA2O2=0.0 !Shut up compiler warnings. -db
IF(CA2.LE.0.D0) TA2O2=(1.D0-CA2)/SA2
IF(CA2.GT.0.D0) TA2O2=SA2/(1.D0+CA2)
A2=2.D0*atan(TA2O2)
IF(A2.LT.0.D0) A2=A2+6.2831853071795864D0
RETURN
END SUBROUTINE DCOORD