GHmsjPolynomials.java
/* Copyright 2002-2016 CS Systèmes d'Information
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package org.orekit.propagation.semianalytical.dsst.utilities;
import org.apache.commons.math3.util.FastMath;
/** Compute the G<sub>ms</sub><sup>j</sup> and the H<sub>ms</sub><sup>j</sup>
* polynomials in the equinoctial elements h, k and the direction cosines α and β
* and their partial derivatives with respect to k, h, α and β.
* <p>
* The expressions used are equations 2.7.5-(1)(2) from the Danielson paper.
* </p>
* @author Romain Di Costanzo
*/
public class GHmsjPolynomials {
/** C<sub>j</sub>(k, h), S<sub>j</sub>(k, h) coefficient.
* (k, h) are the (x, y) component of the eccentricity vector in equinoctial elements
*/
private final CjSjCoefficient cjsjKH;
/** C<sub>j</sub>(α, β), S<sub>j</sub>(α, β) coefficient.
* (α, β) are the direction cosines
*/
private final CjSjCoefficient cjsjAB;
/** Is the orbit represented as a retrograde orbit.
* I = -1 if yes, +1 otherwise.
*/
private int I;
/** Create a set of G<sub>ms</sub><sup>j</sup> and H<sub>ms</sub><sup>j</sup> polynomials.
* @param k X component of the eccentricity vector
* @param h Y component of the eccentricity vector
* @param alpha direction cosine α
* @param beta direction cosine β
* @param retroFactor -1 if the orbit is represented as retrograde, +1 otherwise
**/
public GHmsjPolynomials(final double k, final double h,
final double alpha, final double beta,
final int retroFactor) {
this.cjsjKH = new CjSjCoefficient(k, h);
this.cjsjAB = new CjSjCoefficient(alpha, beta);
this.I = retroFactor;
}
/** Get the G<sub>ms</sub><sup>j</sup> coefficient.
* @param m m subscript
* @param s s subscript
* @param j order
* @return the G<sub>ms</sub><sup>j</sup>
*/
public double getGmsj(final int m, final int s, final int j) {
final int sMj = FastMath.abs(s - j);
double gms = 0d;
if (FastMath.abs(s) <= m) {
final int mMis = m - I * s;
gms = cjsjKH.getCj(sMj) * cjsjAB.getCj(mMis) -
I * sgn(s - j) * cjsjKH.getSj(sMj) * cjsjAB.getSj(mMis);
} else {
final int sMim = FastMath.abs(s - I * m);
gms = cjsjKH.getCj(sMj) * cjsjAB.getCj(sMim) +
sgn(s - j) * sgn(s - m) * cjsjKH.getSj(sMj) * cjsjAB.getSj(sMim);
}
return gms;
}
/** Get the H<sub>ms</sub><sup>j</sup> coefficient.
* @param m m subscript
* @param s s subscript
* @param j order
* @return the H<sub>ms</sub><sup>j</sup>
*/
public double getHmsj(final int m, final int s, final int j) {
final int sMj = FastMath.abs(s - j);
double hms = 0d;
if (FastMath.abs(s) <= m) {
final int mMis = m - I * s;
hms = I * cjsjKH.getCj(sMj) * cjsjAB.getSj(mMis) + sgn(s - j) *
cjsjKH.getSj(sMj) * cjsjAB.getCj(mMis);
} else {
final int sMim = FastMath.abs(s - I * m);
hms = -sgn(s - m) * cjsjKH.getCj(sMj) * cjsjAB.getSj(sMim) +
sgn(s - j) * cjsjKH.getSj(sMj) * cjsjAB.getCj(sMim);
}
return hms;
}
/** Get the dG<sub>ms</sub><sup>j</sup> / d<sub>k</sub> coefficient.
* @param m m subscript
* @param s s subscript
* @param j order
* @return dG<sub>ms</sub><sup>j</sup> / d<sub>k</sub>
*/
public double getdGmsdk(final int m, final int s, final int j) {
final int sMj = FastMath.abs(s - j);
double dGmsdk = 0d;
if (FastMath.abs(s) <= m) {
final int mMis = m - I * s;
dGmsdk = cjsjKH.getDcjDk(sMj) * cjsjAB.getCj(mMis) -
I * sgn(s - j) * cjsjKH.getDsjDk(sMj) * cjsjAB.getSj(mMis);
} else {
final int sMim = FastMath.abs(s - I * m);
dGmsdk = cjsjKH.getDcjDk(sMj) * cjsjAB.getCj(sMim) +
sgn(s - j) * sgn(s - m) * cjsjKH.getDsjDk(sMj) * cjsjAB.getSj(sMim);
}
return dGmsdk;
}
/** Get the dG<sub>ms</sub><sup>j</sup> / d<sub>h</sub> coefficient.
* @param m m subscript
* @param s s subscript
* @param j order
* @return dG<sub>ms</sub><sup>j</sup> / d<sub>h</sub>
*/
public double getdGmsdh(final int m, final int s, final int j) {
final int sMj = FastMath.abs(s - j);
double dGmsdh = 0d;
if (FastMath.abs(s) <= m) {
final int mMis = m - I * s;
dGmsdh = cjsjKH.getDcjDh(sMj) * cjsjAB.getCj(mMis) -
I * sgn(s - j) * cjsjKH.getDsjDh(sMj) * cjsjAB.getSj(mMis);
} else {
final int sMim = FastMath.abs(s - I * m);
dGmsdh = cjsjKH.getDcjDh(sMj) * cjsjAB.getCj(sMim) +
sgn(s - j) * sgn(s - m) * cjsjKH.getDsjDh(sMj) * cjsjAB.getSj(sMim);
}
return dGmsdh;
}
/** Get the dG<sub>ms</sub><sup>j</sup> / d<sub>α</sub> coefficient.
* @param m m subscript
* @param s s subscript
* @param j order
* @return dG<sub>ms</sub><sup>j</sup> / d<sub>α</sub>
*/
public double getdGmsdAlpha(final int m, final int s, final int j) {
final int sMj = FastMath.abs(s - j);
double dGmsdAl = 0d;
if (FastMath.abs(s) <= m) {
final int mMis = m - I * s;
dGmsdAl = cjsjKH.getCj(sMj) * cjsjAB.getDcjDk(mMis) -
I * sgn(s - j) * cjsjKH.getSj(sMj) * cjsjAB.getDsjDk(mMis);
} else {
final int sMim = FastMath.abs(s - I * m);
dGmsdAl = cjsjKH.getCj(sMj) * cjsjAB.getDcjDk(sMim) +
sgn(s - j) * sgn(s - m) * cjsjKH.getSj(sMj) * cjsjAB.getDsjDk(sMim);
}
return dGmsdAl;
}
/** Get the dG<sub>ms</sub><sup>j</sup> / d<sub>β</sub> coefficient.
* @param m m subscript
* @param s s subscript
* @param j order
* @return dG<sub>ms</sub><sup>j</sup> / d<sub>β</sub>
*/
public double getdGmsdBeta(final int m, final int s, final int j) {
final int sMj = FastMath.abs(s - j);
double dGmsdBe = 0d;
if (FastMath.abs(s) <= m) {
final int mMis = m - I * s;
dGmsdBe = cjsjKH.getCj(sMj) * cjsjAB.getDcjDh(mMis) -
I * sgn(s - j) * cjsjKH.getSj(sMj) * cjsjAB.getDsjDh(mMis);
} else {
final int sMim = FastMath.abs(s - I * m);
dGmsdBe = cjsjKH.getCj(sMj) * cjsjAB.getDcjDh(sMim) +
sgn(s - j) * sgn(s - m) * cjsjKH.getSj(sMj) * cjsjAB.getDsjDh(sMim);
}
return dGmsdBe;
}
/** Get the dH<sub>ms</sub><sup>j</sup> / d<sub>k</sub> coefficient.
* @param m m subscript
* @param s s subscript
* @param j order
* @return dH<sub>ms</sub><sup>j</sup> / d<sub>k</sub>
*/
public double getdHmsdk(final int m, final int s, final int j) {
final int sMj = FastMath.abs(s - j);
double dHmsdk = 0d;
if (FastMath.abs(s) <= m) {
final int mMis = m - I * s;
dHmsdk = I * cjsjKH.getDcjDk(sMj) * cjsjAB.getSj(mMis) +
sgn(s - j) * cjsjKH.getDsjDk(sMj) * cjsjAB.getCj(mMis);
} else {
final int sMim = FastMath.abs(s - I * m);
dHmsdk = -sgn(s - m) * cjsjKH.getDcjDk(sMj) * cjsjAB.getSj(sMim) +
sgn(s - j) * cjsjKH.getDsjDk(sMj) * cjsjAB.getCj(sMim);
}
return dHmsdk;
}
/** Get the dH<sub>ms</sub><sup>j</sup> / d<sub>h</sub> coefficient.
* @param m m subscript
* @param s s subscript
* @param j order
* @return dH<sub>ms</sub><sup>j</sup> / d<sub>h</sub>
*/
public double getdHmsdh(final int m, final int s, final int j) {
final int sMj = FastMath.abs(s - j);
double dHmsdh = 0d;
if (FastMath.abs(s) <= m) {
final int mMis = m - I * s;
dHmsdh = I * cjsjKH.getDcjDh(sMj) * cjsjAB.getSj(mMis) +
sgn(s - j) * cjsjKH.getDsjDh(sMj) * cjsjAB.getCj(mMis);
} else {
final int sMim = FastMath.abs(s - I * m);
dHmsdh = -sgn(s - m) * cjsjKH.getDcjDh(sMj) * cjsjAB.getSj(sMim) +
sgn(s - j) * cjsjKH.getDsjDh(sMj) * cjsjAB.getCj(sMim);
}
return dHmsdh;
}
/** Get the dH<sub>ms</sub><sup>j</sup> / d<sub>α</sub> coefficient.
* @param m m subscript
* @param s s subscript
* @param j order
* @return dH<sub>ms</sub><sup>j</sup> / d<sub>α</sub>
*/
public double getdHmsdAlpha(final int m, final int s, final int j) {
final int sMj = FastMath.abs(s - j);
double dHmsdAl = 0d;
if (FastMath.abs(s) <= m) {
final int mMis = m - I * s;
dHmsdAl = I * cjsjKH.getCj(sMj) * cjsjAB.getDsjDk(mMis) +
sgn(s - j) * cjsjKH.getSj(sMj) * cjsjAB.getDcjDk(mMis);
} else {
final int sMim = FastMath.abs(s - I * m);
dHmsdAl = -sgn(s - m) * cjsjKH.getCj(sMj) * cjsjAB.getDsjDk(sMim) +
sgn(s - j) * cjsjKH.getSj(sMj) * cjsjAB.getDcjDk(sMim);
}
return dHmsdAl;
}
/** Get the dH<sub>ms</sub><sup>j</sup> / d<sub>β</sub> coefficient.
* @param m m subscript
* @param s s subscript
* @param j order
* @return dH<sub>ms</sub><sup>j</sup> / d<sub>β</sub>
*/
public double getdHmsdBeta(final int m, final int s, final int j) {
final int sMj = FastMath.abs(s - j);
double dHmsdBe = 0d;
if (FastMath.abs(s) <= m) {
final int mMis = m - I * s;
dHmsdBe = I * cjsjKH.getCj(sMj) * cjsjAB.getDsjDh(mMis) +
sgn(s - j) * cjsjKH.getSj(sMj) * cjsjAB.getDcjDh(mMis);
} else {
final int sMim = FastMath.abs(s - I * m);
dHmsdBe = -sgn(s - m) * cjsjKH.getCj(sMj) * cjsjAB.getDsjDh(sMim) +
sgn(s - j) * cjsjKH.getSj(sMj) * cjsjAB.getDcjDh(sMim);
}
return dHmsdBe;
}
/** Get the sign of an integer.
* @param i number on which evaluation is done
* @return -1 or +1 depending on sign of i
*/
private int sgn(final int i) {
return (i < 0) ? -1 : 1;
}
}