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| author | Ulrich Müller <ulm@gentoo.org> | 2023-02-13 15:50:47 +0100 |
|---|---|---|
| committer | Ulrich Müller <ulm@gentoo.org> | 2023-02-13 15:50:47 +0100 |
| commit | 909bd04cf5fd42744ca5f1f34cb42b48b363ee62 (patch) | |
| tree | c4751c7e861cc4ffdaca53488c955e16eea3bc37 | |
| parent | 10f2aedea9a47a9a12b194344504e418a12b26e5 (diff) | |
| download | emacs-909bd04cf5fd42744ca5f1f34cb42b48b363ee62.tar.gz emacs-909bd04cf5fd42744ca5f1f34cb42b48b363ee62.tar.bz2 emacs-909bd04cf5fd42744ca5f1f34cb42b48b363ee62.zip | |
; * lisp/calendar/lunar.el: Add comments. (bug#61460)
| -rw-r--r-- | lisp/calendar/lunar.el | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/lisp/calendar/lunar.el b/lisp/calendar/lunar.el index 70681f42c90..8ced4144105 100644 --- a/lisp/calendar/lunar.el +++ b/lisp/calendar/lunar.el @@ -85,6 +85,9 @@ remainder mod 4 gives the phase: 0 new moon, 1 first quarter, 2 full moon, (* 0.0107306 time time) (* 0.00001236 time time time)) 360.0)) + ;; moon-lat is the argument of latitude, which is the angle + ;; of the moon measured from the ascending node of its orbit + ;; (i.e. argument of perigee + true anomaly). (moon-lat (mod (+ 21.2964 (* 390.67050646 index) @@ -153,9 +156,11 @@ remainder mod 4 gives the phase: 0 new moon, 1 first quarter, 2 full moon, ;; Line 7000 Peter Duffett-Smith Cambridge University Press 1990 (defun eclipse-check (moon-lat phase) (let* ((moon-lat (* (/ float-pi 180) moon-lat)) + ;; For positions near the ascending or descending node, + ;; calculate the absolute angular distance from that node. (moon-lat (abs (- moon-lat (* (floor (/ moon-lat float-pi)) float-pi)))) - (moon-lat (if (> moon-lat 0.37) + (moon-lat (if (> moon-lat 0.37) ; FIXME (* 0.5 float-pi) (- float-pi moon-lat) moon-lat)) (phase-name (cond ((= phase 0) "Solar") |