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Re: Lat/lon to UTM coords


Please find attached four files for making forward and inverse LL/UTM conversions
bundled into a ZIP file.   These represent the very-hot-off-the-press (ouch!)
revisions.  Luis reported to me some disappointing results using the
International1924 map datum although I had not had any trouble with the WGS84 and
CLARKE 1866 map datums. .  The conversions involve a number of messy algebraic
twistings of series... I suspect that I had a slipped decimal somewhere.  Since I
could not find the problem directly, I simply rekeyed in the whole business; a
remarkable improvement in my typoing skills seems to have corrected most of the
problem.  These implementations duplicate those used as examples in Snyder's
reference.  These implementations still produce about 1km of drifted from the
expected answer for the International 1924 map datum.  I can't explain why the
drift occurs.  I have added the choice of using any one of the map datums listed
in Snyder's reference (about 10 in all).   I can only confirm that these
conversions work for the CLARKE1866 and WGS84 map datums.   (Is it me or does
datums not sound right?)

David Bowman wrote:

> In article <3969C58D.4877FE1B@seadas.bigelow.org>, Ben Tupper
> <tupper@seadas.bigelow.org> wrote:
> > Hello,
> >
> > The book by Snyder (referenced below) is very much worth the $40US.   I have
> > used the following code to convert Lon/Lat to UTM in meters.
> >
> > Ben
> Many thanks for the lat/on to UTM code....  Not to impinge on your
> generosity, but do you have a similar code for the inverse problem, UTM
> to Lat Lon?  USGS Professional Papers are not easy to come by in
> France...  :-)
> cheers,
> David Bowman
> --
> =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
> David Bowman                       "Smash forehead on keyboard to continue."
> Laboratoire Tectonique
> Institut de Physique du Globe - Paris
> 4 Place Jussieu
> 75252 Paris Cedex 05
> France

Ben Tupper
Pemaquid River Company
248 Lower Round Pond Road
POB 106
Bristol, ME 04539

Tel: (207) 563-1048
Email: PemaquidRiver@tidewater.net