public class EpochDerivativesEquations extends Object implements AdditionalDerivativesProvider
Provider computing the partial derivatives
of the state (orbit) with respect to initial state and force models parameters.
This set of equations are automatically added to a numerical propagator
in order to compute partial derivatives of the orbit along with the orbit itself. This is
useful for example in orbit determination applications.
The partial derivatives with respect to initial state can be either dimension 6 (orbit only) or 7 (orbit and mass).
The partial derivatives with respect to force models parameters has a dimension
equal to the number of selected parameters. Parameters selection is implemented at
force models level. Users must retrieve a parameter driver using ParameterDriversProvider.getParameterDriver(String) and then
select it by calling setSelected(true).
If several force models provide different drivers for the
same parameter name, selecting any of these drivers has the side effect of
selecting all the drivers for this shared parameter. In this case, the partial
derivatives will be the sum of the partial derivatives contributed by the
corresponding force models. This case typically arises for central attraction
coefficient, which has an influence on Newtonian attraction, gravity field, and relativity.
| Modifier and Type | Field and Description |
|---|---|
static int |
STATE_DIMENSION
State dimension, fixed to 6.
|
| Constructor and Description |
|---|
EpochDerivativesEquations(String name,
NumericalPropagator propagator)
Simple constructor.
|
| Modifier and Type | Method and Description |
|---|---|
CombinedDerivatives |
combinedDerivatives(SpacecraftState s)
Compute the derivatives related to the additional state (and optionally main state increments).
|
int |
getDimension()
Get the dimension of the generated derivative.
|
String |
getName()
Get the name of the additional derivatives (which will become state once integrated).
|
SpacecraftState |
setInitialJacobians(SpacecraftState s0)
Set the initial value of the Jacobian with respect to state and parameter.
|
SpacecraftState |
setInitialJacobians(SpacecraftState s1,
double[][] dY1dY0,
double[][] dY1dP)
Set the initial value of the Jacobian with respect to state and parameter.
|
void |
setInitialJacobians(SpacecraftState state,
double[][] dY1dY0,
double[][] dY1dP,
double[] p)
Set the Jacobian with respect to state into a one-dimensional additional state array.
|
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, waitinit, yieldspublic static final int STATE_DIMENSION
public EpochDerivativesEquations(String name, NumericalPropagator propagator)
Upon construction, this set of equations is automatically added to
the propagator by calling its AbstractIntegratedPropagator.addAdditionalDerivativesProvider(AdditionalDerivativesProvider) method. So
there is no need to call this method explicitly for these equations.
name - name of the partial derivatives equationspropagator - the propagator that will handle the orbit propagationpublic String getName()
getName in interface AdditionalDerivativesProviderpublic int getDimension()
getDimension in interface AdditionalDerivativesProviderpublic SpacecraftState setInitialJacobians(SpacecraftState s0)
This method is equivalent to call setInitialJacobians(SpacecraftState,
double[][], double[][]) with dYdY0 set to the identity matrix and dYdP set
to a zero matrix.
The force models parameters for which partial derivatives are desired,
must have been selected
before this method is called, so proper matrices dimensions are used.
s0 - initial statepublic SpacecraftState setInitialJacobians(SpacecraftState s1, double[][] dY1dY0, double[][] dY1dP)
The returned state must be added to the propagator (it is not done automatically, as the user may need to add more states to it).
The force models parameters for which partial derivatives are desired,
must have been selected
before this method is called, and the dY1dP matrix dimension must
be consistent with the selection.
s1 - current statedY1dY0 - Jacobian of current state at time t₁ with respect
to state at some previous time t₀ (must be 6x6)dY1dP - Jacobian of current state at time t₁ with respect
to parameters (may be null if no parameters are selected)public void setInitialJacobians(SpacecraftState state, double[][] dY1dY0, double[][] dY1dP, double[] p)
This method converts the Jacobians to Cartesian parameters and put the converted data
in the one-dimensional p array.
state - spacecraft statedY1dY0 - Jacobian of current state at time t₁
with respect to state at some previous time t₀dY1dP - Jacobian of current state at time t₁
with respect to parameters (may be null if there are no parameters)p - placeholder where to put the one-dimensional additional statepublic CombinedDerivatives combinedDerivatives(SpacecraftState s)
combinedDerivatives in interface AdditionalDerivativesProviders - current state information: date, kinematics, attitude, and
additional states this equations depend on (according to the
yields method)Copyright © 2002-2023 CS GROUP. All rights reserved.