[Proj] Transverse Mercator algorithm

Charles Karney ckarney at sarnoff.com
Fri Sep 5 17:21:15 EDT 2008

Gerald I. Evenden wrote:
> BTW: have you determined scale error internal to the procedure.  lproj
> can run an option which will return k for the given point.  It is very
> useful when designing new projection areas.  For example, if the
> longitude width of a "zone" were increased, the k_0 factor should also
> be changed so the scale error at the margins somewhat matches the
> error at the CM so that the overall scale error is minimal.

I posted approximate formulas for the k and convergence of the
Transverse Mercator projection in


These approximations are quite good.  Follow the link in the E-mail for
a tabulation of the error.

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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