Name

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      ELL_LOXODROME

Purpose

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      Deal with loxodromes on ellipsoidal earth.

Category

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Calling Sequence

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      ell_loxodrome, lng1, lat1

Inputs

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      lng1 = Longitude of starting point (P1). in
      lat1 = Latitude of starting point (P1). in
        This point must be a scalar value.

Keyword Parameters

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Keywords

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        LNG2=lng2 Longitude of ending point (P2).
        LAT2=lat2 Latitude of ending point.
        AZI=azi Azimuth (deg) of loxodrome from P1 to P2.
        DIST=dist Distance (m) along loxodrome from P1 to P2.
        /P2 Compute lng2, lat2 from lng1, lat1, azi, and dist.
        /AD Compute azi and dist from P1 and P2.

Outputs

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Common Blocks

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Notes

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      Notes: Algorithms from John Snyder, Map Projections -
        A Working Manual.
        The starting point must be a scalar value. For /P2
        AZI must be a scalar, DIST may be an array (avoid 0 dist).
        For /AD P2 (lng2,lat2) may be an array.
        Be careful, for extreme cases LAT2 may go > 90.
        Use ellipsoid,set=name to set working ellipsoid

Modification History

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      R. Sterner, 2002 Apr 09
      R. Sterner, 2002 Apr 28 --- Cleaned up to allow some array values.
      R. Sterner, 2002 May 01 --- Now calls ellipsoid.
      R. Sterner, 2002 Oct 07 --- Fixed negative range when lat1=lat2,
      found by Rick Chapman when he ported it to the Palm.
      R. Sterner, 2006 Dec 27 --- Fixed the problem of going the wrong
      way around the world found by Rick Chapman in Oct 2002.
      R. Sterner, 2006 Dec 28 --- Cleaned up some lose ends.
      This routine should be split into two:
      ell_lox_rb2ll.pro From range and bearing compute new pt lon, lat.
      ell_lox_ll2rb.pro From point 2 lon, lat compute range and bearing.
      where range and bearing are the loxodromic values.
      Use same calling syntax as ell_rb2ll, ell_ll2rb.
      R. Sterner, 2010 May 04 --- Converted arrays from () to [].
  Copyright (C) 2002, Johns Hopkins University/Applied Physics Laboratory
  This software may be used, copied, or redistributed as long as it is not
  sold and this copyright notice is reproduced on each copy made. This
  routine is provided as is without any express or implied warranties
  whatsoever. Other limitations apply as described in the file disclaimer.txt.