public async Task SetDate(Date date, CrdsGeographical geoLocation)
{
await Task.Run(() =>
{
double jd0 = date.ToJulianEphemerisDay();
daysInMonth = Date.DaysInMonth(date.Year, date.Month);
var eL = new PointF[5];
var eB = new PointF[5];
var eR = new PointF[5];
var jL = new PointF[5];
var jB = new PointF[5];
var jR = new PointF[5];
var earth = new CrdsHeliocentrical[5];
var jupiter = new CrdsHeliocentrical[5];
// calculate heliocentrical positions of Earth and Jupiter for 5 instants
// and find least squares approximation model of planets position
// to quick calculation of Galilean moons postions.
for (int i = 0; i < 5; i++)
{
double jd = jd0 + (i / 4.0) * daysInMonth;
earth[i] = PlanetPositions.GetPlanetCoordinates(3, jd);
jupiter[i] = PlanetPositions.GetPlanetCoordinates(5, jd);
}
double[] earthL = earth.Select(x => x.L).ToArray();
double[] earthB = earth.Select(x => x.B).ToArray();
double[] earthR = earth.Select(x => x.R).ToArray();
double[] jupiterL = jupiter.Select(x => x.L).ToArray();
double[] jupiterB = jupiter.Select(x => x.B).ToArray();
double[] jupiterR = jupiter.Select(x => x.R).ToArray();
// it's important to align longitudes (avoid 0 degrees crossing)
// before applying least squares method
earthL = Angle.Align(earthL);
jupiterL = Angle.Align(jupiterL);
for (int i = 0; i < 5; i++)
{
eL[i] = new PointF(i, (float)earthL[i]);
eB[i] = new PointF(i, (float)earthB[i]);
eR[i] = new PointF(i, (float)earthR[i]);
jL[i] = new PointF(i, (float)jupiterL[i]);
jB[i] = new PointF(i, (float)jupiterB[i]);
jR[i] = new PointF(i, (float)jupiterR[i]);
}
Begin = jd0;
End = jd0 + daysInMonth;
GeoLocation = geoLocation;
this.eL = LeastSquares.FindCoeffs(eL, 3);
this.eB = LeastSquares.FindCoeffs(eB, 3);
this.eR = LeastSquares.FindCoeffs(eR, 3);
this.jL = LeastSquares.FindCoeffs(jL, 3);
this.jB = LeastSquares.FindCoeffs(jB, 3);
this.jR = LeastSquares.FindCoeffs(jR, 3);
});
}
