81 lines
1.9 KiB
FortranFixed
81 lines
1.9 KiB
FortranFixed
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!c****************************************************************
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subroutine getangs(pos,vel,vec,elp,r_az,r_lk)BIND(C, NAME='getangs_C')
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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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use, intrinsic :: iso_c_binding
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use linalg3module
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implicit none
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!c INPUT VARIABLES:
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real(C_DOUBLE), dimension(3) :: pos
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real(C_DOUBLE), dimension(3) :: vel
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real(C_DOUBLE), dimension(3) :: vec
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!c OUTPUT VARIABLES:
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real(C_DOUBLE) :: r_az
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real(C_DOUBLE) :: 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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type (ellipsoidType) elp
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!C FUNCTION STATEMENTS:
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! real(C_DOUBLE) dot
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!c PROCESSING STEPS:
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!c compute a TCN basis vector set
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call latlon(elp,pos,r_llh,XYZ_2_LLH)
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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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r_dd = dot(r_n,vec)
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r_vecnorm = norm(vec)
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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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end subroutine getangs
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