agi.foundation.celestial

(agi.foundation.orbitpropagation-2022r2.jar)

Class SphericalHarmonicGravityCoefficients

java.lang.Object

agi.foundation.celestial.SphericalHarmonicGravityCoefficients

public class SphericalHarmonicGravityCoefficients
extends Object

Contains the coefficient data for a spherical harmonic gravity model.

Constructor Summary

Constructors

Constructor and Description
SphericalHarmonicGravityCoefficients(double[] zonalCoefficients, double[][] cosineCoefficients, double[][] sineCoefficients) Initializes a new instance from the provided coefficients.
SphericalHarmonicGravityCoefficients(int degree, int order) Initializes a new instance according to the provided parameters.

Method Summary

Modifier and Type	Method and Description
static SphericalHarmonicGravityCoefficients	createEarthPermanentTideCoefficients() Creates a set of the default IERS 2003 permanent tide coefficients for Earth.
double[][]	getCosineCoefficients() Gets the list of cosine coefficients (m= [1, L])
int	getDegree() Gets the maximum degree of the gravitation coefficients.
int	getOrder() Gets the maximum order of the gravitation coefficients.
double[][]	getSineCoefficients() Gets the list of sine coefficients (m= [1, L])
double[]	getZonalCoefficients() Gets the list of zonal coefficients (the negative of the cosine coefficients for m=0; J2 = -C20, J3 = -C30, etc.).

Methods inherited from class java.lang.Object

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

Constructor Detail

SphericalHarmonicGravityCoefficients

public SphericalHarmonicGravityCoefficients(int degree,
                                            int order)

Initializes a new instance according to the provided parameters.

Parameters:

degree - The degree of the coefficient set.

order - The order of the coefficient set.

SphericalHarmonicGravityCoefficients

public SphericalHarmonicGravityCoefficients(@Nonnull
                                            double[] zonalCoefficients,
                                            @Nonnull
                                            double[][] cosineCoefficients,
                                            @Nonnull
                                            double[][] sineCoefficients)

Initializes a new instance from the provided coefficients. Degree and order are inferred from the shapes of the gravity coefficient arrays.

An consistent gravity field of degree 2 and order 0 would be inferred from a zonalCoefficients array that is size double[3] with cosineCoefficients array that is size double[3][] with cosineCoefficients[0] a double[1], cosineCoefficients[1] a double[1], and cosineCoefficients[2] a double[1]. The sineCoefficients array must be the same size and shape as the cosineCoefficients array. All of the values inside the cosine and sine coefficient arrays should be 0.0 if the order is 0, but this is not enforced. The cosine coefficients are 0.0 because the zonal coefficients incorporate the order 0 terms as J2 = -C20, J3 = -C30, etc. The sine coefficients S20, S30, etc. are 0.0 by definition.

A consistent gravity field of degree 2 and order 1 would be inferred from a zonalCoefficients array that is size double[3] with cosineCoefficients array that is size double[3][] with cosineCoefficients[0] a double[1], cosineCoefficients[1] a double[2], and cosineCoefficients[2] a double[2]. The sineCoefficients array must be the same size and shape as the cosineCoefficients array. Any gravity field with degree greater than 2 and order 1 would have any cosineCoefficients[3] and higher as double[2] as well. The order 0 terms of the cosine and sine arrays should be 0.0 (e.g. sineCoefficients[2][0] == 0.0), but the higher-order terms are typically non-zero (e.g. cosineCoefficients[2][1] != 0.0).

A consistent gravity field of degree and order 2 would be inferred from a zonalCoefficients array that is size double[3] with cosineCoefficients array that is size double[3][] with cosineCoefficients[0] a double[1], cosineCoefficients[1] a double[2], and cosineCoefficients[2] a double[3]. The sineCoefficients array must be the same size and shape as the cosineCoefficients array. Any gravity field with equal degrees and orders would have linearly increasing sizes of the inner double arrays. For example, a gravity field of degree and order 3 would have its cosineCoefficient[3] a double[4].

Parameters:

zonalCoefficients - The zonal gravity coefficients (J2 = -C20, J3 = -C30, etc.).

cosineCoefficients - The cosine gravity coefficients (C21, C22, C31, etc.).

sineCoefficients - The sine gravity coefficients (S21, S22, S31, etc.).

Throws:

ArgumentNullException - Thrown when zonalCoefficients, cosineCoefficients, or sineCoefficients are null.

ArgumentException - Thrown when the input gravity coefficient arrays have inconsistent sizes or shapes with each other or with the inferred degree and order of the gravity field.

Method Detail

getDegree

public final int getDegree()

Gets the maximum degree of the gravitation coefficients.

getOrder

public final int getOrder()

Gets the maximum order of the gravitation coefficients.

getZonalCoefficients

public final double[] getZonalCoefficients()

Gets the list of zonal coefficients (the negative of the cosine coefficients for m=0; J2 = -C20, J3 = -C30, etc.).

getCosineCoefficients

public final double[][] getCosineCoefficients()

Gets the list of cosine coefficients (m= [1, L])

getSineCoefficients

public final double[][] getSineCoefficients()

Gets the list of sine coefficients (m= [1, L])

createEarthPermanentTideCoefficients

@Nonnull
public static SphericalHarmonicGravityCoefficients createEarthPermanentTideCoefficients()

Creates a set of the default IERS 2003 permanent tide coefficients for Earth. These are identical to those created by the default constructor of PermanentSolidTideModel.

Returns:

The default IERS 2003 permanent tide coefficients for Earth.