105 lines
2.0 KiB
Fortran
105 lines
2.0 KiB
Fortran
c****************************************************************
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subroutine getangs(pos,vel,vec,r_az,r_lk)
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c****************************************************************
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c**
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c** FILE NAME: getangs.f
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c**
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c** DATE WRITTEN: 4-94
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c**
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c** PROGRAMMER:par
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c**
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c** FUNCTIONAL DESCRIPTION: This subroutine will compute the look
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c** vector given the look angle,azimuth angle, and the position
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c** vector.
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c**
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c** ROUTINES CALLED:cross,unitvec,lincomb
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c**
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c** NOTES: none
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c**
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c** UPDATE LOG:
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c**
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c*****************************************************************
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implicit none
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c INPUT VARIABLES:
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real*8 pos(3), vel(3)
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real*8 vec(3)
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c OUTPUT VARIABLES:
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real*8 r_az, r_lk
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c LOCAL VARIABLES:
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real*8 tvt, tvc,tvn, r_a, r_e2, lat, lon, rad
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real*8 r_temp(3),r_t(3),r_c(3),r_n(3), r_dd
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real*8 r_vecnorm, r_llh(3)
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c structure /ellipsoid/
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c real*8 r_a
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c real*8 r_e2
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c end structure
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c record /ellipsoid/ elp
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type ellipsoid
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sequence
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real (8) r_a
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real (8) r_e2
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end type ellipsoid
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type (ellipsoid) elp
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common /ellipsoid/ r_a, r_e2
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c DATA STATEMENTS:
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integer i_xyztollh,i_llhtoxyz
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parameter(i_xyztollh=2, i_llhtoxyz=1)
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C FUNCTION STATEMENTS:
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real*8 dot
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c PROCESSING STEPS:
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c compute a TCN basis vector set
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elp%r_a = r_a
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elp%r_e2 = r_e2
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call latlon(elp,pos,r_llh,i_xyztollh)
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lat = r_llh(1)
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lon = r_llh(2)
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rad = r_llh(3)
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r_n(1) = -cos(lat)*cos(lon)
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r_n(2) = -cos(lat)*sin(lon)
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r_n(3) = -sin(lat)
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c only good for sphere
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c
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c call unitvec(pos,r_n)
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c do i=1,3
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c r_n(i) = -r_n(i)
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c enddo
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r_dd = dot(r_n,vec)
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call norm(vec,r_vecnorm)
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r_lk = acos(r_dd/r_vecnorm)
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call cross(r_n,vel,r_temp)
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call unitvec(r_temp,r_c)
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call cross(r_c,r_n,r_temp)
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call unitvec(r_temp,r_t)
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c compute the angles
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tvt = dot(r_t,vec)
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tvc = dot(r_c,vec)
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tvn = dot(r_n,vec)
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r_az = atan2(tvc,tvt)
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c r_lk = atan2(tvc,tvn)
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c r_lk = -999999.
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end
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