# NavList:

## A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

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Re: Equations for Mercator projections?
From: Herbert Prinz
Date: 2003 Apr 15, 00:10 +0000

```Dear Prof. Kuenning,

The formula can be found in any standard textbook on geodesy, map
projections or the like, in any school library. If these "students"
(doesn't this word come from 'studeo' = to devote oneself ?) have not had
any success in finding the equations on the Web on any of the dozens of
sites that have them, it's probably because they don't know what to look
for. In this case, they should not even try to program the formula. There
are already enough people out there who know all about the difference
between Perl and awk, or what have you, and nothing about the problems
that they are supposed to solve with these tools. I trust that as a
responsible teacher you will steer your students into the right direction.

For your orientation, a google search for 'mercator projection'  brings up

http://www.posc.org/Epicentre.2_2/DataModel/ExamplesofUsage/eu_cs34f.html
http://www.beanpaste.com/BSG/mercator.html
etc., etc.

I hope this helps.

Best regards

Herbert Prinz

P.S.

You should also be aware that the problem, as you state it, is
underdetermined. There is no such thing as "the scale of a Mercator map".

P.P.S.

So, who is Henry Spencer, and what's his relevance to navigation?

geoff@CS.HMC.EDU wrote:

> I have some students who need to be able to convert lat/long into x/y
> coordinates on a Mercator projection.  They know the lat/long of the
> upper-left corner and the scale of the map.  They haven't had any
> success finding equations on the Web.  Does anybody have any pointers?
> --
>     Geoff Kuenning   geoff@cs.hmc.edu   http://www.cs.hmc.edu/~geoff/
>
> Perl is awk with skin cancer.
>                 -- Henry Spencer

```
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