[Proj] Transverse Mercator algorithm
Charles Karney
ckarney at sarnoff.com
Thu Sep 4 15:58:12 EDT 2008
Charles Karney wrote:
> It'll take a day or so to make my macsyma code for the exact transverse
> Mercator transformation presentable.
OK, I've posted the maxima code for the arbitrary precision transversion
Mercator projection. Go to
http://charles.karney.info/geographic/
and download tm.mac and ellint.mac. There's some meager documentation
in tm.mac.
Start maxima and enter
load("tm.mac")$
xya:tm1(0b0,90b0)$
float(xya);
lla:ll1(xya[1],xya[2])$
float(lla);
This converts the point 0N 90E to transverse Mercator (for WGS84) and
back to latitude and longitude.
float(xya) gives
[2.595359284541359E+7, 9997964.943020998, 90.0, 18.40462279198669]
which is [easting(m), northing(m), convergence(deg), scale].
float(lla) gives [- 1.600614476517369E-82, 90.0] which approximates the
starting point.
The precision is 120 digits; so you should be typically getting results
which are good to at least half that many digits.
--
Charles Karney <ckarney at sarnoff.com>
Sarnoff Corporation, Princeton, NJ 08543-5300
URL: http://charles.karney.info
Tel: +1 609 734 2312
Fax: +1 609 734 2662
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