Subject: Re: bug#61460: 30.0.50; Calendar shows eclipse for quarter moon

From: Michael Heerdegen <[email-masked]>
Date: Mon, 13 Feb 2023 09:13:00 +0100

Ulrich Mueller <[email-masked]> writes:

> IIUC, the goal is to calculate the angular distance from the ascending
> or descending node, whichever is closer. So one wants this:
>
>      0° ->  0°
>     10° -> 10°
>    ...
>    170° -> 10°
>    180° ->  0°
>    190° -> 10°
>    ...
>    350° -> 10°

Ok, thanks.  So the input value is the longitude?

> The only thing that I don't understand is the constant 0.37. I would
> have expected pi/2 (= 90°) there. Probably it doesn't matter, because
> below it checks for (< moon-lat 0.37), so any larger value will be
> ignored.

Maybe you gained slightly faster code on a really old computer - the
book that is mentioned in the code is quite old.  In theory this allows
you to get rid of one `if' statement (the comparison against 0.37 is
performed anyway).  And yes, it doesn't affect the result.

Michael.