private void ReadPlanetConstants(SEFileData data)
{
foreach (var ipli in data.PlanetNumbers)
{
var pdp = new PlanetData();
pdp.InternalBodyNumber = ipli;
pdp.FileIndexStart = ReadInt32();
pdp.Flags = (PlanetFlags)_stream.ReadByte();
pdp.CoefficientsNumber = _stream.ReadByte();
pdp.NormalizationFactor = ReadInt32() / 1000.0;
var doubles = ReadDoubles(10);
pdp.StartDate = JulianDayNumber.FromRaw(doubles[0]);
pdp.EndDate = JulianDayNumber.FromRaw(doubles[1]);
pdp.SegmentSize = doubles[2];
pdp.IndexEntriesCount = (int)((doubles[1] - doubles[0] + 0.1) / doubles[2]);
pdp.ElementsEpoch = doubles[3];
pdp.Prot = doubles[4];
pdp.Dprot = doubles[5];
pdp.Qrot = doubles[6];
pdp.Dqrot = doubles[7];
pdp.Perigee = doubles[8];
pdp.DPerigee = doubles[9];
if (pdp.Flags.HasFlag(PlanetFlags.Ellipse))
{
pdp.ReferenceEllipseCoefficients = ReadDoubles(2 * pdp.CoefficientsNumber);
}
var index = ipli >= SEConsts.AseroidOffset
? InternalPlanets.AnyBody
: (InternalPlanets)ipli;
data.PlanetsData[index] = pdp;
}
}
/// <summary>
/// start and end epoch of file
/// </summary>
private (JulianDayNumber, JulianDayNumber) ReadFilePeriod()
{
var buff = ReadDoubles(2);
double start = buff[0];
double end = buff[1];
return(JulianDayNumber.FromRaw(start), JulianDayNumber.FromRaw(end));
}
/// <summary>
/// Stephenson & Morrison (2004)
/// </summary>
public static double Calc(JulianDayNumber tjd, double tid_acc)
{
double ans = 0, ans2, ans3;
double p, B, dd;
double tjd0;
int iy;
double Y = tjd.GetGregorianYear();
/* before -1000:
* formula by Stephenson & Morrison (2004; p. 335) but adjusted to fit the
* starting point of table dt2. */
if (Y < DeltaTTabulated.Tab2Start)
{
// before -1000
ans = DeltaTLongtermMorrisonStephenson.Calc(tjd);
ans = TidalAcceleration.AdjustForTidalAcceleration(ans, Y, tid_acc, TidalAccelerationMode.Const26, false);
/* transition from formula to table over 100 years */
if (Y >= DeltaTTabulated.Tab2Start - 100)
{
/* starting value of table dt2: */
ans2 = TidalAcceleration.AdjustForTidalAcceleration(DeltaTTabulated.dt2[0], DeltaTTabulated.Tab2Start, tid_acc, TidalAccelerationMode.Const26, false);
/* value of formula at epoch TAB2_START */
/* B = (TAB2_START - LTERM_EQUATION_YSTART) * 0.01;
* ans3 = -20 + LTERM_EQUATION_COEFF * B * B;*/
tjd0 = (DeltaTTabulated.Tab2Start - 2000) * 365.2425 + (double)JulianDayNumber.J2000;
ans3 = DeltaTLongtermMorrisonStephenson.Calc(JulianDayNumber.FromRaw(tjd0));
ans3 = TidalAcceleration.AdjustForTidalAcceleration(ans3, Y, tid_acc, TidalAccelerationMode.Const26, false);
dd = ans3 - ans2;
B = (Y - (DeltaTTabulated.Tab2Start - 100)) * 0.01;
/* fit to starting point of table dt2. */
ans -= dd * B;
}
}
/* between -1000 and 1600:
* linear interpolation between values of table dt2 (Stephenson & Morrison 2004) */
if (Y >= DeltaTTabulated.Tab2Start && Y < DeltaTTabulated.Tab2End)
{
double Yjul = tjd.GetJulianYear();
p = Math.Floor(Yjul);
iy = (int)((p - DeltaTTabulated.Tab2Start) / DeltaTTabulated.Tab2Step);
dd = (Yjul - (DeltaTTabulated.Tab2Start + DeltaTTabulated.Tab2Step * iy)) / DeltaTTabulated.Tab2Step;
ans = DeltaTTabulated.dt2[iy] + (DeltaTTabulated.dt2[iy + 1] - DeltaTTabulated.dt2[iy]) * dd;
/* correction for tidal acceleration used by our ephemeris */
ans = TidalAcceleration.AdjustForTidalAcceleration(ans, Y, tid_acc, TidalAccelerationMode.Const26, false);
}
ans /= 86400.0;
return(ans);
}
/// <summary>
/// Fetch chebyshew coefficients from sweph file
/// </summary>
/// <param name="pdp">Planet</param>
/// <param name="jd">Time</param>
/// <param name="epsilonJ2000">Epsilon for J2000</param>
/// <see cref="get_new_segment"/>
internal SEFileSegment ReadSegment(PlanetData pdp, JulianDayNumber jd, Epsilon epsilonJ2000)
{
int segmentNumber = (int)((jd - pdp.StartDate).Raw / pdp.SegmentSize);
var segmentStart = pdp.StartDate + JulianDayNumber.FromRaw(pdp.SegmentSize * segmentNumber);
var fpos = pdp.FileIndexStart + segmentNumber * 3;
fpos = ReadInt32From3Bytes(fpos);
_stream.Seek(fpos, SeekOrigin.Begin);
var rmax = pdp.NormalizationFactor;
double[] segp = new double[pdp.CoefficientsNumber * 3];
// read coefficients for 3 coordinates
for (var icoord = 0; icoord < 3; icoord++)
{
var idbl = icoord * pdp.CoefficientsNumber;
// first read header
// first bit indicates number of sizes of packed coefficients
int nco;
int nsizes;
int[] nsize = new int[6];
var c = ReadData(1, 2);
if ((c[0] & 128) > 0)
{
var c2 = ReadData(1, 2);
nsizes = 6;
nsize[0] = c[1] / 16;
nsize[1] = c[1] % 16;
nsize[2] = c2[0] / 16;
nsize[3] = c2[0] % 16;
nsize[4] = c2[1] / 16;
nsize[5] = c2[1] % 16;
nco = nsize[0] + nsize[1] + nsize[2] + nsize[3] + nsize[4] + nsize[5];
}
else
{
nsizes = 4;
nsize[0] = c[0] / 16;
nsize[1] = c[0] % 16;
nsize[2] = c[1] / 16;
nsize[3] = c[1] % 16;
nco = nsize[0] + nsize[1] + nsize[2] + nsize[3];
}
// there may not be more coefficients than interpolation order + 1
if (nco > pdp.CoefficientsNumber)
{
throw new FormatException($"Error in ephemeris file: {nco} coefficients instead of {pdp.CoefficientsNumber}");
}
// now unpack
for (var i = 0; i < nsizes; i++)
{
if (nsize[i] == 0)
{
continue;
}
if (i < 4)
{
int j = 4 - i;
int k = nsize[i];
var longs = ReadUints(j, k);
for (int m = 0; m < k; m++)
{
if ((longs[m] & 1) > 0) // will be negative
{
segp[idbl] = -(((longs[m] + 1) / 2) / 1e+9 * rmax / 2);
}
else
{
segp[idbl] = (longs[m] / 2) / 1e+9 * rmax / 2;
}
idbl++;
}
}
else if (i == 4) // half byte packing
{
int k = (nsize[i] + 1) / 2;
var longs = ReadUints(1, k);
for (int m = 0, j = 0;
m < k && j < nsize[i];
m++)
{
for (int n = 0, o = 16;
n < 2 && j < nsize[i];
n++, j++, idbl++, longs[m] %= (uint)o, o /= 16)
{
if ((longs[m] & o) > 0)
{
segp[idbl] = -(((longs[m] + o) / o / 2) * rmax / 2 / 1e+9);
}
else
{
segp[idbl] = (longs[m] / o / 2) * rmax / 2 / 1e+9;
}
}
}
}
else if (i == 5) // quarter byte packing
{
int k = (nsize[i] + 3) / 4;
var longs = ReadUints(1, k);
for (int m = 0, j = 0;
m < k && j < nsize[i];
m++)
{
for (int n = 0, o = 64;
n < 4 && j < nsize[i];
n++, j++, idbl++, longs[m] %= (uint)o, o /= 4)
{
if ((longs[m] & o) > 0)
{
segp[idbl] = -(((longs[m] + o) / o / 2) * rmax / 2 / 1e+9);
}
else
{
segp[idbl] = (longs[m] / o / 2) * rmax / 2 / 1e+9;
}
}
}
}
}
}
int evaluateCoefficientsCount = pdp.Flags.HasFlag(PlanetFlags.Rotate)
? RotateBack(pdp, segmentStart, segp, epsilonJ2000)
: pdp.CoefficientsNumber;
var segment = new SEFileSegment(segmentStart, JulianDayNumber.FromRaw(pdp.SegmentSize), segp, evaluateCoefficientsCount);
return(segment);
}
