[Proj] Transverse Mercator algorithm

Gerald I. Evenden geraldi.evenden at gmail.com
Fri Sep 5 12:56:35 EDT 2008

A couple of notes:

1. Of the etmerc, ktmerc and ftmerc extended range versions of TM, etmerc 
appears to be the winner in precision as one approaches 90,0.  When I figure 
out how to get maxima to generate a grid of numbers I will try to make a 
contour plot of precision comparisons.  Thus the combination of highest speed 
and best precision goes to Denmark.

2. I tried out tmerc along the CM which tests my version of M(phi) or meridian 
distance procedure that I revised a couple of years ago against the maxima 
procedure.  Scripts and results follow:

(%i12) xya:tm1(90b0,0b0)$ float(xya);
(%o13)    [0.0, 9997964.943020998, - 6.837286269353478E-119, 0.9996]

gie at charon:~$ lproj +proj=tmerc +ellps=WGS84 +k_0=0.9996 -f %.9f
0 90
0.000000000     9997964.943020998

The whole religious complexion of the modern world is due
to the absence from Jerusalem of a lunatic asylum.
-- Havelock Ellis (1859-1939) British psychologist

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