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George Huxtable wrote:
>
> Basic on a pocket calculator, ready to test. I have taken heed of Paul's
> warning about a misprint. If he can recall anything about that misprint, or
> in what way the problem showed up, it would be good to learn more.


I have more on this. Following the link Herbert Prinz provided to this
page

http://www.posc.org/Epicentre.2_2/DataModel/ExamplesofUsage/eu_cs34h.html

, I think I've found the typo in the Explanatory Supplement to the
Astronomical Almanac (1992 edition).

The book and Web page both appear to use the same formulas, with
slight differences in the variable names. Look at the variable the Web
page denotes with Greek letter nu (resembles v) in the Easting and
Northing formulas. There's a little problem with the page layout, in
that it doesn't include the formula for nu with the other auxiliary
quantities such as T and C. However, if you read on a bit, it's there.
(Just delete the "1" subscript from nu and phi.)

Now turn to the Explanatory Supplement. It uses N sub phi rather than
nu. The formula for N sub phi is on page 210. But this formula is
quite different from the one for nu on the Web page. In fact, it's
identical to the formula for rho sub 1, immediately below!

Thankfully, we can clear this up because the Web page includes a fully
worked example, including values for auxiliary quantities. (Those who
would post math online, take note.) I was able to confirm that the
formula for nu does yield the stated value. Also, the wrong formula in
the book yields a value fairly close but definitely not right. That
matches my recollection of what I saw several years ago when trying to
code the Explanatory Supplement formulas.

By the way, I used Geotrans to check that Web page's example, which
converts lat/lon to British National Grid. The page is correct.

   

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