deltaLongitudeAbs function
Returns the shortest longitude angle distance (in degrees) between two
points A and B with longitudes given by longADeg
respectively longBDeg
,
both in degrees.
The result is always positive, in the range of 0..180 (both inclusive).
Implementation
double deltaLongitudeAbs(double longADeg, double longBDeg) {
// Longitude calculations require a bit of care as it's expressed in the
// range -180..180, so LongA=-179 and LongB=179 is just 2 degrees difference,
// not 358 degrees.
var diffLongDeg = (longADeg - longBDeg).abs();
return diffLongDeg <= 180 ? diffLongDeg : 360 - diffLongDeg;
}