Next message: Herbert Prinz: "Re: Uses of almanacs for astrology"
Herbert P wrote:
"I believe you are mistaken. There is no resemblance to Kepler's
equation. The characteristic feature of the latter is that the variable
E (eccentric anomaly) appears as a term E as well as a term sin E,
making it impossible to express E as explicit function of the mean
anomaly. "
Here's the direct equation for the calculation of the true altitude from the
observed altitude and the horizontal parallax:
TA = OA - HP cos TA .
OK? You agree, I hope, that this bears a very STRONG resemblance to Kepler's
equation. Now invert it. Solve for TA. Can't be done in "closed form", right?
See what I mean now?? If you solve this iteratively for TA to, say, one part
in a million and then compare with the Arctan solution, you will get slightly
different results. They are not inverses. They solve slightly different
mathematical problems. That's the "trivia" I was getting at.
Frank R
[ ] Mystic, Connecticut
[X] Chicago, Illinois
