/** {@inheritDoc} */
public void computeShortPeriodicsCoefficients(final SpacecraftState state)
throws OrekitException {
// Initialise the Hansen coefficients
for (int s = -maxDegree; s <= maxDegree; s++) {
// coefficients with j == 0 are always needed
this.hansenObjects[s + maxDegree][0].computeInitValues(e2, chi, chi2);
if (!mDailiesOnly) {
// initialize other objects only if required
for (int j = 1; j <= jMax; j++) {
this.hansenObjects[s + maxDegree][j].computeInitValues(e2, chi, chi2);
}
}
}
// Compute coefficients
tesseralSPCoefs.computeCoefficients(state.getDate());
}
/** {@inheritDoc} */
@Override
public void resetShortPeriodicsCoefficients() {
if (tesseralSPCoefs != null) {
tesseralSPCoefs.resetCoefficients();
}
}
/** {@inheritDoc} */
@Override
public double[] getShortPeriodicVariations(final AbsoluteDate date, final double[] meanElements)
throws OrekitException {
// Initialise the short periodic variations
final double[] shortPeriodicVariation = new double[] {0., 0., 0., 0., 0., 0.};
// Compute only if there is at least one non-resonant tesseral or
// only the m-daily tesseral should be taken into account
if (!nonResOrders.isEmpty() || mDailiesOnly) {
// Build an Orbit object from the mean elements
final Orbit meanOrbit =
OrbitType.EQUINOCTIAL.mapArrayToOrbit(
meanElements, PositionAngle.MEAN, date, provider.getMu(), this.frame);
// Build an auxiliary object
final AuxiliaryElements aux = new AuxiliaryElements(meanOrbit, I);
// Central body rotation angle from equation 2.7.1-(3)(4).
final Transform t = bodyFrame.getTransformTo(aux.getFrame(), aux.getDate());
final Vector3D xB = t.transformVector(Vector3D.PLUS_I);
final Vector3D yB = t.transformVector(Vector3D.PLUS_J);
final double currentTheta =
FastMath.atan2(
-f.dotProduct(yB) + I * g.dotProduct(xB), f.dotProduct(xB) + I * g.dotProduct(yB));
// Add the m-daily contribution
for (int m = 1; m <= maxOrderMdailyTesseralSP; m++) {
// Phase angle
final double jlMmt = -m * currentTheta;
final double sinPhi = FastMath.sin(jlMmt);
final double cosPhi = FastMath.cos(jlMmt);
// compute contribution for each element
for (int i = 0; i < 6; i++) {
shortPeriodicVariation[i] +=
tesseralSPCoefs.getCijm(i, 0, m, date) * cosPhi
+ tesseralSPCoefs.getSijm(i, 0, m, date) * sinPhi;
}
}
// loop through all non-resonant (j,m) pairs
for (final Map.Entry<Integer, List<Integer>> entry : nonResOrders.entrySet()) {
final int m = entry.getKey();
final List<Integer> listJ = entry.getValue();
for (int j : listJ) {
// Phase angle
final double jlMmt = j * meanElements[5] - m * currentTheta;
final double sinPhi = FastMath.sin(jlMmt);
final double cosPhi = FastMath.cos(jlMmt);
// compute contribution for each element
for (int i = 0; i < 6; i++) {
shortPeriodicVariation[i] +=
tesseralSPCoefs.getCijm(i, j, m, date) * cosPhi
+ tesseralSPCoefs.getSijm(i, j, m, date) * sinPhi;
}
}
}
}
return shortPeriodicVariation;
}
