RosettaCodeData/Task/Haversine-formula/Pascal/haversine-formula.pascal

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Program HaversineDemo(output);
uses
Math;
function haversineDist(th1, ph1, th2, ph2: double): double;
const
diameter = 2 * 6372.8;
var
dx, dy, dz: double;
begin
ph1 := degtorad(ph1 - ph2);
th1 := degtorad(th1);
th2 := degtorad(th2);
dz := sin(th1) - sin(th2);
dx := cos(ph1) * cos(th1) - cos(th2);
dy := sin(ph1) * cos(th1);
haversineDist := arcsin(sqrt(dx**2 + dy**2 + dz**2) / 2) * diameter;
end;
begin
writeln ('Haversine distance: ', haversineDist(36.12, -86.67, 33.94, -118.4):7:2, ' km.');
end.