raku-rosettacode/programming_tasks/H/Haversine_formula.md

Haversine formula

class EarthPoint {
        has $.lat; # latitude
        has $.lon; # longitude
 
        has $earth_radius = 6371; # mean earth radius
        has $radian_ratio = pi / 180;
 
        # accessors for radians
        method latR { $.lat * $radian_ratio }
        method lonR { $.lon * $radian_ratio }
 
        method haversine-dist(EarthPoint $p) {
 
                my EarthPoint $arc .= new(
                        lat => $!lat - $p.lat,
                        lon => $!lon - $p.lon );
 
                my $a = sin($arc.latR/2) ** 2 + sin($arc.lonR/2) ** 2
                        * cos($.latR) * cos($p.latR);
                my $c = 2 * asin( sqrt($a) );
 
                return $earth_radius * $c;
        }
}
 
my EarthPoint $BNA .= new(lat => 36.12, lon => -86.67);
my EarthPoint $LAX .= new(lat => 33.94, lon => -118.4);
 
say $BNA.haversine-dist($LAX); # 2886.44444099822