;;; solar.el --- calendar functions for solar events
-;; Copyright (C) 1992, 1993, 1995, 1997, 2001, 2002, 2003, 2004, 2005,
-;; 2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc.
+;; Copyright (C) 1992-1993, 1995, 1997, 2001-2012
+;; Free Software Foundation, Inc.
;; Author: Edward M. Reingold <reingold@cs.uiuc.edu>
;; Denis B. Roegel <Denis.Roegel@loria.fr>
(st (+ solar-sidereal-time-greenwich-midnight
(* ut 1.00273790935)))
;; Hour angle (in degrees).
- (ah (- (* st 15) (* 15 (car ec)) (* -1 (calendar-longitude))))
+ (ah (- (* st 15) (* 15 (car ec)) (* -1 longitude)))
(de (cadr ec))
(azimuth (solar-atn2 (- (* (solar-cosine-degrees ah)
(solar-sin-degrees latitude))
`calendar-daylight-savings-starts-time', `calendar-daylight-savings-ends',
`calendar-daylight-savings-ends-time', `calendar-daylight-time-offset',
and `calendar-time-zone' are used to interpret local time."
- (let* ((long)
- (start d)
- (start-long (solar-longitude d))
- (next (mod (* l (1+ (floor (/ start-long l)))) 360))
- (end (+ d (* (/ l 360.0) 400)))
- (end-long (solar-longitude end)))
- (while ; bisection search for nearest minute
- (< 0.00001 (- end start))
- ;; start <= d < end
+ (let ((start d)
+ (next (mod (* l (1+ (floor (/ (solar-longitude d) l)))) 360))
+ (end (+ d (* (/ l 360.0) 400)))
+ long)
+ ;; Bisection search for nearest minute.
+ (while (< 0.00001 (- end start))
+ ;; start <= d < end
;; start-long <= next < end-long when next != 0
- ;; when next = 0, we look for the discontinuity (start-long is near 360
- ;; and end-long is small (less than l).
+ ;; when next = 0, look for the discontinuity (start-long is near 360
+ ;; and end-long is small (less than l)).
(setq d (/ (+ start end) 2.0)
long (solar-longitude d))
(if (or (and (not (zerop next)) (< long next))
(and (zerop next) (< l long)))
- (setq start d
- start-long long)
- (setq end d
- end-long long)))
+ (setq start d)
+ (setq end d)))
(/ (+ start end) 2.0)))
;; FIXME but there already is solar-sunrise-sunset.
(defun solar-mean-equinoxes/solstices (k year)
"Julian day of mean equinox/solstice K for YEAR.
K=0, spring equinox; K=1, summer solstice; K=2, fall equinox; K=3, winter
-solstice. These formulae are only to be used between 1000 BC and 3000 AD."
+solstice. These formulas are only to be used between 1000 BC and 3000 AD."
(let ((y (/ year 1000.0))
(z (/ (- year 2000) 1000.0)))
(if (< year 1000) ; actually between -1000 and 1000
(provide 'solar)
-;; arch-tag: bc0ff693-df58-4666-bde4-2a7837ccb8fe
;;; solar.el ends here