gistfile1.tcl

proc gc_distance {pos1 pos2} {
	set pi 3.1415926535
	set lat1 [deg2rad [lindex $pos1 0]]
	set lon1 [deg2rad [lindex $pos1 1]]
	set lat2 [deg2rad [lindex $pos2 0]]
	set lon2 [deg2rad [lindex $pos2 1]]
	set theta [expr $lon2 - $lon1]
	set dist [expr acos((sin($lat1) * sin($lat2)) + (cos($lat1) * cos($lat2) * cos($theta)))]
	if {$dist < 0} {
		set dist [expr $dist + $pi]
	}
	expr $dist * 3958.9
}
proc get_coords {icao} {
	set ical [string toupper $icao]
	if [cache exists airport_cache $icao] {
		return [cache get airport_cache $icao]
	}
	set addr "http://maps.google.com/maps/geo?output=csv&oe=utf-8&q=$icao&key=ABQIAAAAdsSAw1O-7omKe7LKXavpFRQh99ZTDzCKrh6sdHmT446MSWVSuhQasqJRpIgMOXXBU7v4pHuaaCd2rA"
	set api_output [split [cwget $addr] ","];
	if {[lindex $api_output 0] != 200} then {error "geo api failed"};
	set coords [lrange $api_output 2 3]
	cache put airport_cache $icao $coords
	return $coords
}
proc airport_distance {icao1 icao2} {
	format "$icao1-$icao2: %.2f miles" [gc_distance [get_coords $icao1] [get_coords $icao2]]
}