GNU bug report logs - #61460
30.0.50; Calendar shows eclipse for quarter moon

Previous Next

Full log

Message #41 received at 61460 <at> debbugs.gnu.org (full text, mbox):

From: Michael Heerdegen <michael_heerdegen <at> web.de>
To: Ulrich Mueller <ulm <at> gentoo.org>
Cc: 61460 <at> debbugs.gnu.org
Subject: Re: bug#61460: 30.0.50; Calendar shows eclipse for quarter moon
Date: Mon, 13 Feb 2023 09:13:00 +0100

Ulrich Mueller <ulm <at> gentoo.org> 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.

Previous Next

GNU bug tracking system
Copyright (C) 1999 Darren O. Benham, 1997,2003 nCipher Corporation Ltd, 1994-97 Ian Jackson.