org.orekit.orbits

Class OrbitHermiteInterpolator

java.lang.Object

org.orekit.time.AbstractTimeInterpolator<Orbit>

org.orekit.orbits.AbstractOrbitInterpolator

org.orekit.orbits.OrbitHermiteInterpolator

All Implemented Interfaces:

TimeInterpolator<Orbit>

public class OrbitHermiteInterpolator
extends AbstractOrbitInterpolator

Class using a Hermite interpolator to interpolate orbits.

Depending on given sample orbit type, the interpolation may differ :

• For Keplerian, Circular and Equinoctial orbits, the interpolated instance is created by polynomial Hermite interpolation, using derivatives when available.
• For Cartesian orbits, the interpolated instance is created using the cartesian derivatives filter given at instance construction. Hence, it will fall back to Lagrange interpolation if this instance has been designed to not use derivatives.

In any case, it should be used only with small number of interpolation points (about 10-20 points) in order to avoid Runge's phenomenon and numerical problems (including NaN appearing).

Author:

Luc Maisonobe, Vincent Cucchietti

See Also:

Orbit, HermiteInterpolator

Nested Class Summary

Nested classes/interfaces inherited from class org.orekit.time.AbstractTimeInterpolator

AbstractTimeInterpolator.InterpolationData

Field Summary

Fields inherited from class org.orekit.time.AbstractTimeInterpolator

DEFAULT_EXTRAPOLATION_THRESHOLD_SEC, DEFAULT_INTERPOLATION_POINTS

Constructor Summary

Constructors

Constructor and Description
OrbitHermiteInterpolator(Frame outputInertialFrame) Constructor with : Default number of interpolation points of DEFAULT_INTERPOLATION_POINTS Default extrapolation threshold value (DEFAULT_EXTRAPOLATION_THRESHOLD_SEC s) Use of position and two time derivatives during interpolation As this implementation of interpolation is polynomial, it should be used only with small number of interpolation points (about 10-20 points) in order to avoid Runge's phenomenon and numerical problems (including NaN appearing).
OrbitHermiteInterpolator(int interpolationPoints, double extrapolationThreshold, Frame outputInertialFrame, CartesianDerivativesFilter pvaFilter) Constructor.
OrbitHermiteInterpolator(int interpolationPoints, Frame outputInertialFrame) Constructor with : Default extrapolation threshold value (DEFAULT_EXTRAPOLATION_THRESHOLD_SEC s) Use of position and two time derivatives during interpolation As this implementation of interpolation is polynomial, it should be used only with small number of interpolation points (about 10-20 points) in order to avoid Runge's phenomenon and numerical problems (including NaN appearing).
OrbitHermiteInterpolator(int interpolationPoints, Frame outputInertialFrame, CartesianDerivativesFilter pvaFilter) Constructor with default extrapolation threshold value (DEFAULT_EXTRAPOLATION_THRESHOLD_SEC s).

Method Summary

Modifier and Type	Method and Description
CartesianDerivativesFilter	getPVAFilter() Get filter for derivatives from the sample to use in position-velocity-acceleration interpolation.
protected Orbit	interpolate(AbstractTimeInterpolator.InterpolationData interpolationData) Interpolate instance from given interpolation data.

Methods inherited from class org.orekit.orbits.AbstractOrbitInterpolator

checkOrbitsConsistency, getOutputInertialFrame, interpolate

Methods inherited from class org.orekit.time.AbstractTimeInterpolator

addOptionalSubInterpolatorIfDefined, checkInterpolatorCompatibilityWithSampleSize, getCentralDate, getExtrapolationThreshold, getNbInterpolationPoints, getSubInterpolators, getTimeParameter, interpolate

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

OrbitHermiteInterpolator

public OrbitHermiteInterpolator(Frame outputInertialFrame)

Constructor with :

• Default number of interpolation points of DEFAULT_INTERPOLATION_POINTS
• Default extrapolation threshold value (DEFAULT_EXTRAPOLATION_THRESHOLD_SEC s)
• Use of position and two time derivatives during interpolation

As this implementation of interpolation is polynomial, it should be used only with small number of interpolation points (about 10-20 points) in order to avoid Runge's phenomenon and numerical problems (including NaN appearing).

Parameters:

outputInertialFrame - output inertial frame

OrbitHermiteInterpolator

public OrbitHermiteInterpolator(int interpolationPoints,
                                Frame outputInertialFrame)

Constructor with :

• Default extrapolation threshold value (DEFAULT_EXTRAPOLATION_THRESHOLD_SEC s)
• Use of position and two time derivatives during interpolation

As this implementation of interpolation is polynomial, it should be used only with small number of interpolation points (about 10-20 points) in order to avoid Runge's phenomenon and numerical problems (including NaN appearing).

Parameters:

interpolationPoints - number of interpolation points

outputInertialFrame - output inertial frame

OrbitHermiteInterpolator

public OrbitHermiteInterpolator(int interpolationPoints,
                                Frame outputInertialFrame,
                                CartesianDerivativesFilter pvaFilter)

Constructor with default extrapolation threshold value (DEFAULT_EXTRAPOLATION_THRESHOLD_SEC s).

As this implementation of interpolation is polynomial, it should be used only with small number of interpolation points (about 10-20 points) in order to avoid Runge's phenomenon and numerical problems (including NaN appearing).

Parameters:

interpolationPoints - number of interpolation points

outputInertialFrame - output inertial frame

pvaFilter - filter for derivatives from the sample to use in position-velocity-acceleration interpolation. Used only when interpolating Cartesian orbits.

OrbitHermiteInterpolator

public OrbitHermiteInterpolator(int interpolationPoints,
                                double extrapolationThreshold,
                                Frame outputInertialFrame,
                                CartesianDerivativesFilter pvaFilter)

Constructor.

As this implementation of interpolation is polynomial, it should be used only with small number of interpolation points (about 10-20 points) in order to avoid Runge's phenomenon and numerical problems (including NaN appearing).

Parameters:

interpolationPoints - number of interpolation points

extrapolationThreshold - extrapolation threshold beyond which the propagation will fail

outputInertialFrame - output inertial frame

pvaFilter - filter for derivatives from the sample to use in position-velocity-acceleration interpolation. Used only when interpolating Cartesian orbits.

Method Detail

getPVAFilter

public CartesianDerivativesFilter getPVAFilter()

Get filter for derivatives from the sample to use in position-velocity-acceleration interpolation.

Returns:

filter for derivatives from the sample to use in position-velocity-acceleration interpolation

interpolate

protected Orbit interpolate(AbstractTimeInterpolator.InterpolationData interpolationData)

Interpolate instance from given interpolation data.

Depending on given sample orbit type, the interpolation may differ :

• For Keplerian, Circular and Equinoctial orbits, the interpolated instance is created by polynomial Hermite interpolation, using derivatives when available.
• For Cartesian orbits, the interpolated instance is created using the cartesian derivatives filter given at instance construction. Hence, it will fall back to Lagrange interpolation if this instance has been designed to not use derivatives.

If orbit interpolation on large samples is needed, using the Ephemeris class is a better way than using this low-level interpolation. The Ephemeris class automatically handles selection of a neighboring sub-sample with a predefined number of point from a large global sample in a thread-safe way.

Specified by:

interpolate in class AbstractTimeInterpolator<Orbit>

Parameters:

interpolationData - interpolation data

Returns:

interpolated instance at given date