public static function Calculate_LatLonAlt($_time, Predict_Vector $pos, Predict_Geodetic $geodetic)
{
/* Reference: The 1992 Astronomical Almanac, page K12. */
/* double r,e2,phi,c; */
$geodetic->theta = Predict_Math::AcTan($pos->y, $pos->x);
/*radians*/
$geodetic->lon = Predict_Math::FMod2p($geodetic->theta - Predict_Time::ThetaG_JD($_time));
/*radians*/
$r = sqrt($pos->x * $pos->x + $pos->y * $pos->y);
$e2 = Predict::__f * (2 - Predict::__f);
$geodetic->lat = Predict_Math::AcTan($pos->z, $r);
/*radians*/
do {
$phi = $geodetic->lat;
$sinPhi = sin($phi);
$c = 1 / sqrt(1 - $e2 * ($sinPhi * $sinPhi));
$geodetic->lat = Predict_Math::AcTan($pos->z + Predict::xkmper * $c * $e2 * $sinPhi, $r);
} while (abs($geodetic->lat - $phi) >= 1.0E-10);
$geodetic->alt = $r / cos($geodetic->lat) - Predict::xkmper * $c;
/*kilometers*/
if ($geodetic->lat > Predict::pio2) {
$geodetic->lat -= Predict::twopi;
}
}
