bug#20606: Fwd: bug#20414: Fwd: lunar.el

[Nicholas Strauss <nicholas.strauss@gmail.com>]

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---------- Forwarded message ----------
From: Nicholas Strauss <nicholas.strauss@gmail.com>
Date: Mon, May 18, 2015 at 10:59 AM
Subject: Re: bug#20414: Fwd: lunar.el
To: Glenn Morris <rgm@gnu.org>


Hi Glenn,

You are right. I have a bug. Two conditions must be met -- the lunar
latitude must be near 0 AND the phase must be full e.g. longitude.

Code should read,
   (if (or (= phase 0)
            (= phase 2))
        (cond ((< moon-lat 2.42600766e-1)
               (concat "** " phase-name " Eclipse **"))
              ((< moon-lat 0.37)
               (concat "** " phase-name " Eclipse possible **"))
              (t
               "")
              )
      "")
    )
I will send a new patch/diff file.

Here is new listing:
Saturday, April 4, 2015: Full Moon 5:04am (PDT) ** Lunar Eclipse **
Saturday, April 11, 2015: Last Quarter Moon 8:50pm (PDT)
Saturday, April 18, 2015: New Moon 11:59am (PDT) ** Solar Eclipse possible **
Saturday, April 25, 2015: First Quarter Moon 4:57pm (PDT)
Sunday, May 3, 2015: Full Moon 8:41pm (PDT)
Monday, May 11, 2015: Last Quarter Moon 3:42am (PDT)
Sunday, May 17, 2015: New Moon 9:16pm (PDT)
Monday, May 25, 2015: First Quarter Moon 10:21am (PDT)
Tuesday, June 2, 2015: Full Moon 9:18am (PDT)
Tuesday, June 9, 2015: Last Quarter Moon 8:48am (PDT)
Tuesday, June 16, 2015: New Moon 7:08am (PDT)
Wednesday, June 24, 2015: First Quarter Moon 4:04am (PDT)
Wednesday, July 1, 2015: Full Moon 7:18pm (PDT)
Wednesday, July 8, 2015: Last Quarter Moon 1:31pm (PDT)
Wednesday, July 15, 2015: New Moon 6:26pm (PDT)
Thursday, July 23, 2015: First Quarter Moon 9:05pm (PDT)
Friday, July 31, 2015: Full Moon 3:41am (PDT)
Thursday, August 6, 2015: Last Quarter Moon 7:10pm (PDT)
Friday, August 14, 2015: New Moon 7:55am (PDT)
Saturday, August 22, 2015: First Quarter Moon 12:32pm (PDT)
Saturday, August 29, 2015: Full Moon 11:33am (PDT)
Saturday, September 5, 2015: Last Quarter Moon 3:01am (PDT)
Saturday, September 12, 2015: New Moon 11:43pm (PDT) ** Solar Eclipse **
Monday, September 21, 2015: First Quarter Moon 2:00am (PDT)
Sunday, September 27, 2015: Full Moon 7:48pm (PDT) ** Lunar Eclipse **
Sunday, October 4, 2015: Last Quarter Moon 2:12pm (PDT)
Monday, October 12, 2015: New Moon 5:07pm (PDT)
Tuesday, October 20, 2015: First Quarter Moon 1:32pm (PDT)
Tuesday, October 27, 2015: Full Moon 5:02am (PDT)
Tuesday, November 3, 2015: Last Quarter Moon 4:29am (PST)

Nick

On Mon, May 18, 2015 at 12:01 AM, Glenn Morris <rgm@gnu.org> wrote:
>
> Thanks for this.
> What's the difference between "eclipse" and "eclipse possible"?
>
> It predicts eclipses when the moon is quarter-full, which seems wrong?
>
> Tuesday, June 9, 2015: Last Quarter Moon 8:48am (PDT) **  Eclipse possible **
> Tuesday, June 16, 2015: New Moon 7:08am (PDT)
> Wednesday, June 24, 2015: First Quarter Moon 4:04am (PDT) **  Eclipse **

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93a94
> 	 (eclipse (eclipse-check moon-lat phase))
149c150,187
<     (list (car adj) (apply 'solar-time-string (cdr adj)) phase)))
---
>     (list (car adj) (apply 'solar-time-string (cdr adj)) phase eclipse)))
> 
> ;; from "Astronomy with your Personal Computer",
> ;; Subroutine Eclipse Line 7000
> ;; Peter Duffett-Smith Cambridge University Press 1990
> ;; -ncs klas Thu Apr 23 14:34:12 PDT 2015
> (defun eclipse-check (moon-lat phase)
>   (let*
>       ((M_PI                        3.1415926535)
>        (moon-lat (* (/ M_PI 180)
> 		    moon-lat))
>        (moon-lat (abs (- moon-lat
> 			 (*
> 			  (floor
> 			   (/ moon-lat 
> 			      M_PI)
> 			   )
> 			  M_PI)
> 			 )
> 		      )
> 		 )
>        (moon-lat (cond ((> moon-lat 0.37) (- M_PI moon-lat))
> 		       (t moon-lat)))
>        (phase-name (cond ((= phase 0) "Solar")
>                          ((= phase 2) "Lunar")
>                          (t ""))))
>     (if (or (= phase 0)
> 	    (= phase 2))
> 	(cond ((< moon-lat 2.42600766e-1)
> 	       (concat "** " phase-name " Eclipse **"))
> 	      ((< moon-lat 0.37)
> 	       (concat "** " phase-name " Eclipse possible **"))
> 	      (t
> 	       "")
> 	      )
>       "")
>     )
> )
225c263
<             (format "%s: %s %s" (calendar-date-string (car x))
---
>             (format "%s: %s %s %s" (calendar-date-string (car x))
227c265,267
<                     (cadr x)))
---
>                     (cadr x)
> 		    (car (last x))
> 		    ))