83 lines
2.5 KiB
FortranFixed
83 lines
2.5 KiB
FortranFixed
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c****************************************************************
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subroutine latlon_elp(r_a,r_e2,r_v,r_lat,r_lon,r_h,i_type)
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c****************************************************************
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c**
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c** FILE NAME: latlon.f
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c**
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c** DATE WRITTEN:7/22/93
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c**
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c** PROGRAMMER:Scott Hensley
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c**
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c** FUNCTIONAL DESCRIPTION:This program converts a vector to
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c** lat,lon and height above the reference ellipsoid or given a
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c** lat,lon and height produces a geocentric vector.
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c**
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c** ROUTINES CALLED:none
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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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integer i_type !1=lat,lon to vector,2= vector to lat,lon
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real*8 r_a !ellispoid semi-major axis
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real*8 r_e2 !ellipsoid eccentricity squared
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real*8 r_v(3) !geocentric vector (meters)
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real*8 r_lat !latitude (deg -90 to 90)
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real*8 r_lon !longitude (deg -180 to 180)
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real*8 r_h !height above ellipsoid (meters)
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c OUTPUT VARIABLES:see input
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c LOCAL VARIABLES:
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integer i_ft
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real*8 pi,r_dtor,r_re,r_q2,r_q3,r_b,r_q
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real*8 r_p,r_tant,r_theta
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c DATA STATEMENTS:
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data pi /3.141592653589793238d0/
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data r_dtor /1.74532925199d-2/
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data i_ft /0/
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C FUNCTION STATEMENTS:
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c PROCESSING STEPS:
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if(i_type .eq. 1)then !convert lat,lon to vector
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r_re = r_a/sqrt(1.d0 - r_e2*sin(r_lat)**2)
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r_v(1) = (r_re + r_h)*cos(r_lat)*cos(r_lon)
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r_v(2) = (r_re + r_h)*cos(r_lat)*sin(r_lon)
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r_v(3) = (r_re*(1.d0-r_e2) + r_h)*sin(r_lat)
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elseif(i_type .eq. 2)then !convert vector to lat,lon
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r_q2 = 1.d0/(1.d0 - r_e2)
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r_q = sqrt(r_q2)
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r_q3 = r_q2 - 1.d0
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r_b = r_a*sqrt(1.d0 - r_e2)
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r_lon = atan2(r_v(2),r_v(1))
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r_p = sqrt(r_v(1)**2 + r_v(2)**2)
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r_tant = (r_v(3)/r_p)*r_q
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r_theta = atan(r_tant)
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r_tant = (r_v(3) + r_q3*r_b*sin(r_theta)**3)/
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+ (r_p - r_e2*r_a*cos(r_theta)**3)
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r_lat = atan(r_tant)
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r_re = r_a/sqrt(1.d0 - r_e2*sin(r_lat)**2)
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r_h = r_p/cos(r_lat) - r_re
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endif
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end
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