/// <summary>
/// Compute the eccentric anomaly 'E'
/// </summary>
/// <param name="eccentricity"></param>
/// <param name="meanAnomaly"></param>
/// <returns></returns>
internal static double GetEccentricAnomaly(double eccentricity, DegreeModel meanAnomaly)
{
var iteration = 0;
var maxIterationsiteration = 1000000;
var tolerance = Math.Pow(10, -10);
var eccentricAnomalyDegrees = new DegreeModel(DegreeHelper.RadiansToDegrees(eccentricity));
var result = meanAnomaly.Degrees + (eccentricAnomalyDegrees.Degrees * MathDegrees.Sin(meanAnomaly.Degrees));
while (iteration < maxIterationsiteration)
{
var deltaMeanAnomaly = meanAnomaly.Degrees - (result - (eccentricAnomalyDegrees.Degrees * MathDegrees.Sin(result)));
var deltaEccentricAnomaly = deltaMeanAnomaly / (1 - (eccentricity * MathDegrees.Cos(result)));
result = result + deltaEccentricAnomaly;
if (Math.Abs(deltaEccentricAnomaly) < tolerance)
{
return(result);
}
iteration++;
}
return(result);
}
/// <summary>
/// Compute the eccentric anomaly 'E'
/// </summary>
/// <param name="eccentricity"></param>
/// <param name="meanAnomaly"></param>
/// <param name="tolerance">number of decimal positions</param>
/// <param name="maximumIterations"></param>
/// <returns></returns>
internal static double GetEccentricAnomaly2(double eccentricity, DegreeModel meanAnomaly, double tolerance, double maximumIterations)
{
var delta = Math.Pow(10, -tolerance);
var ma = meanAnomaly.Degrees;
ma = ma / 360.0;
ma = 2 * Math.PI * (ma - Math.Floor(ma));
var eccentricAnomaly = eccentricity < 0.8 ? ma : Math.PI;
var calculateF = eccentricAnomaly - (eccentricity * Math.Sin(ma)) - ma;
double i = 0;
while (Math.Abs(calculateF) > delta && i < maximumIterations)
{
eccentricAnomaly = eccentricAnomaly - (calculateF / (1.0 - (eccentricity * Math.Cos(eccentricAnomaly))));
calculateF = eccentricAnomaly - (eccentricity * Math.Sin(eccentricAnomaly)) - ma;
i++;
}
eccentricAnomaly = DegreeHelper.RadiansToDegrees(eccentricAnomaly);
var result = Math.Round(eccentricAnomaly * Math.Pow(10, tolerance)) / Math.Pow(10, tolerance);
return(result);
}
private static double GetHourHorizon(
this CelestialObjectPositionModel celestialObjectPosition,
double latitudeDegrees,
double h0)
{
if (h0.EqualsWithinTolerance(0, 6))
{
return(DegreeHelper.RadiansToDegrees(
Math.Acos(
-MathDegrees.Tan(latitudeDegrees) *
MathDegrees.Tan(celestialObjectPosition.Declination))));
}
return(DegreeHelper.RadiansToDegrees(Math.Acos(
(MathDegrees.Sin(h0) - (MathDegrees.Sin(latitudeDegrees) * MathDegrees.Sin(celestialObjectPosition.Declination))) /
(MathDegrees.Cos(latitudeDegrees) * MathDegrees.Cos(celestialObjectPosition.Declination)))));
}
internal static SkyPositionModel GetSkyPosition(
double declination,
double latitude,
DateTimeOffset dateTimeOffset,
double siderealTime)
{
var azimuth =
DegreeHelper.RadiansToDegrees(
Math.Atan2(
MathDegrees.Sin(siderealTime),
(MathDegrees.Cos(siderealTime) * MathDegrees.Sin(latitude)) - (MathDegrees.Tan(declination) * MathDegrees.Cos(latitude))));
var height =
DegreeHelper.RadiansToDegrees(
Math.Asin(
(MathDegrees.Sin(latitude) * MathDegrees.Sin(declination)) +
(MathDegrees.Cos(latitude) * MathDegrees.Cos(declination) * MathDegrees.Cos(siderealTime))));
return(new SkyPositionModel(dateTimeOffset, height, azimuth));
}
public void RadiansToDegreesTest(double value, double expected)
{
var actual = DegreeHelper.RadiansToDegrees(value);
Assert.True(expected.EqualsWithinTolerance(actual, 6), $"expected {expected} and actual {actual} are not equal.");
}
