computeTime method
Implementation
double computeTime(var G, double t) {
final D = sunPosition(_JDate + t)['declination']!;
final Z = _computeMidDay(t);
final V = 1 / 15 *
darccos((-dsin(G) - dsin(D) * dsin(_lat)) / (dcos(D) * dcos(_lat)));
return Z + (G > 90 ? -V : V);
}