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Re: distance from Easter Island to Chile
From: |
Emanuel Berg |
Subject: |
Re: distance from Easter Island to Chile |
Date: |
Mon, 21 Apr 2014 04:16:49 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) |
giacomo.boffi@gmail.com writes:
> (progn (defun d2r (x) (/ (* pi x) 180)) ...
Aha, degrees-to-radians is a macro, won't play with
mapcar (?). Did some improvements (I hope) to the
interface:
(defun d2r (d) (/ (* pi d) 180))
(defun spherical-law-of-cosines (p1 p2)
(let ((lat1 (car p1)) (lon1 (cadr p1))
(lat2 (car p2)) (lon2 (cadr p2)))
(acos (+ (* (sin lat1) (sin lat2))
(* (cos lat1) (cos lat2) (cos (- lon2 lon1)))))))
(defun distance-2 (p1 p2)
(let*((from (car p1))
(from-coords-r (mapcar 'd2r (cadr p1)))
(to (car p2))
(to-coords-r (mapcar 'd2r (cadr p2)))
(dist (* 6378.1
(spherical-law-of-cosines from-coords-r
to-coords-r)) ))
(message (format "%s -> %s: %8.2f km" from to dist)) ))
(setq p1 '("Santiago" (33.4500 70.6667)))
(setq p2 '("Easter Island" (27.1167 109.3667)))
(distance-2 p1 p2)
Now we just need a database of locations, then we can
really go nuts...
--
underground experts united:
http://user.it.uu.se/~embe8573
- distance from Easter Island to Chile, Emanuel Berg, 2014/04/19
- Re: distance from Easter Island to Chile, Frank Stutzman, 2014/04/20
- Re: distance from Easter Island to Chile, Emanuel Berg, 2014/04/20
- Re: distance from Easter Island to Chile, giacomo . boffi, 2014/04/20
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- Re: distance from Easter Island to Chile, Emanuel Berg, 2014/04/20
- Re: distance from Easter Island to Chile, Emanuel Berg, 2014/04/20
- Re: distance from Easter Island to Chile, giacomo . boffi, 2014/04/21
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- Re: distance from Easter Island to Chile, Emanuel Berg, 2014/04/21
- Re: distance from Easter Island to Chile, Emanuel Berg, 2014/04/21
- Re: distance from Easter Island to Chile, Emanuel Berg, 2014/04/22
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- Re: distance from Easter Island to Chile,
Emanuel Berg <=
Re: distance from Easter Island to Chile, Barry Margolin, 2014/04/20
Re: distance from Easter Island to Chile, Eli Zaretskii, 2014/04/20
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Re: distance from Easter Island to Chile, Emanuel Berg, 2014/04/20
Re: distance from Easter Island to Chile, Emanuel Berg, 2014/04/21