76 lines
1.3 KiB
Fortran
76 lines
1.3 KiB
Fortran
!c****************************************************************
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!c
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!c Various curvature functions
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!c
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!c
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!c****************************************************************
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!c**
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!c** FILE NAME: curvature.f
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!c**
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!c** DATE WRITTEN: 12/02/93
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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 routine computes the curvature for
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!c** of various types required for ellipsoidal or spherical earth
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!c** calculations.
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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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real*8 function reast(r_a,r_e2,r_lat)
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implicit none
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real*8 r_a,r_e2,r_lat
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reast = r_a/sqrt(1.d0 - r_e2*sin(r_lat)**2)
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end
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real*8 function rnorth(r_a,r_e2,r_lat)
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implicit none
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real*8 r_a,r_e2,r_lat
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rnorth = (r_a*(1.d0 - r_e2))/(1.d0 - r_e2*sin(r_lat)**2)**(1.5d0)
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end
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real*8 function rdir(r_a,r_e2,r_hdg,r_lat)
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implicit none
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real*8 r_a,r_e2,r_lat,r_hdg,r_re,r_rn,reast,rnorth
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r_re = reast(r_a,r_e2,r_lat)
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r_rn = rnorth(r_a,r_e2,r_lat)
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rdir = (r_re*r_rn)/(r_re*cos(r_hdg)**2 + r_rn*sin(r_hdg)**2)
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end
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