20 lines
768 B
R
20 lines
768 B
R
dms_to_rad <- function(d, m, s) (d + m / 60 + s / 3600) * pi / 180
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# Volumetric mean radius is 6371 km, see http://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.html
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# The diameter is thus 12742 km
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great_circle_distance <- function(lat1, long1, lat2, long2) {
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a <- sin(0.5 * (lat2 - lat1))
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b <- sin(0.5 * (long2 - long1))
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12742 * asin(sqrt(a * a + cos(lat1) * cos(lat2) * b * b))
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}
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# Coordinates are found here:
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# http://www.airport-data.com/airport/BNA/
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# http://www.airport-data.com/airport/LAX/
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great_circle_distance(
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dms_to_rad(36, 7, 28.10), dms_to_rad( 86, 40, 41.50), # Nashville International Airport (BNA)
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dms_to_rad(33, 56, 32.98), dms_to_rad(118, 24, 29.05)) # Los Angeles International Airport (LAX)
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# Output: 2886.327
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