Tide.java
/* Copyright 2002-2021 CS GROUP
* Licensed to CS GROUP (CS) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* CS licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.orekit.models.earth.displacement;
import org.orekit.data.BodiesElements;
/**
* Class representing a tide.
* @since 9.1
* @author Luc Maisonobe
*/
public class Tide {
/** M₂ tide. */
public static final Tide M2 = new Tide(255555);
/** S₂ tide. */
public static final Tide S2 = new Tide(273555);
/** N₂ tide. */
public static final Tide N2 = new Tide(245655);
/** K₂ tide. */
public static final Tide K2 = new Tide(275555);
/** K₁ tide. */
public static final Tide K1 = new Tide(165555);
/** O₁ tide. */
public static final Tide O1 = new Tide(145555);
/** P₁ tide. */
public static final Tide P1 = new Tide(163555);
/** Q₁ tide. */
public static final Tide Q1 = new Tide(135655);
/** Mf tide. */
public static final Tide MF = new Tide(75555);
/** Mm tide. */
public static final Tide MM = new Tide(65455);
/** Ssa tide. */
public static final Tide SSA = new Tide(57555);
/** Doodson number. */
private final int doodsonNumber;
/** Multipliers for Doodson arguments (τ, s, h, p, N', ps). */
private final int[] doodsonMultipliers;
/** Multipliers for Delaunay arguments (l, l', F, D, Ω). */
private final int[] delaunayMultipliers;
/** Simple constructor.
* @param cTau coefficient for mean lunar time
* @param cS coefficient for mean longitude of the Moon
* @param cH coefficient for mean longitude of the Sun
* @param cP coefficient for longitude of Moon mean perigee
* @param cNprime negative of the longitude of the Moon's mean ascending node on the ecliptic
* @param cPs coefficient for longitude of Sun mean perigee
*/
public Tide(final int cTau, final int cS, final int cH, final int cP, final int cNprime, final int cPs) {
doodsonNumber = doodsonMultipliersToDoodsonNumber(cTau, cS, cH, cP, cNprime, cPs);
doodsonMultipliers = new int[] {
cTau, cS, cH, cP, cNprime, cPs
};
this.delaunayMultipliers = doodsonMultipliersToDelaunayMultipliers(doodsonMultipliers);
}
/** Simple constructor.
* @param doodsonNumber Doodson Number
*/
public Tide(final int doodsonNumber) {
this.doodsonNumber = doodsonNumber;
this.doodsonMultipliers = doodsonNumberToDoodsonMultipliers(doodsonNumber);
this.delaunayMultipliers = doodsonMultipliersToDelaunayMultipliers(doodsonMultipliers);
}
/** Convert Doodson number to Doodson mutipliers.
* @param doodsonNumber Doodson number
* @return Doodson multipliers
*/
private static int[] doodsonNumberToDoodsonMultipliers(final int doodsonNumber) {
// CHECKSTYLE: stop Indentation check
return new int[] {
(doodsonNumber / 100000) % 10,
((doodsonNumber / 10000) % 10) - 5,
((doodsonNumber / 1000) % 10) - 5,
((doodsonNumber / 100) % 10) - 5,
((doodsonNumber / 10) % 10) - 5,
(doodsonNumber % 10) - 5
};
// CHECKSTYLE: resume Indentation check
}
/** Convert Doodson mutipliers to Doodson number.
* @param cTau coefficient for mean lunar time
* @param cS coefficient for mean longitude of the Moon
* @param cH coefficient for mean longitude of the Sun
* @param cP coefficient for longitude of Moon mean perigee
* @param cNprime negative of the longitude of the Moon's mean ascending node on the ecliptic
* @param cPs coefficient for longitude of Sun mean perigee
* @return Doodson number
*/
private static int doodsonMultipliersToDoodsonNumber(final int cTau, final int cS, final int cH,
final int cP, final int cNprime, final int cPs) {
return ((((cTau * 10 + (cS + 5)) * 10 + (cH + 5)) * 10 + (cP + 5)) * 10 + (cNprime + 5)) * 10 + (cPs + 5);
}
/** Convert Doodson mutipliers to Delaunay multipliers.
* @param dom Doodson multipliers
* @return Delaunay multipliers
*/
private static int[] doodsonMultipliersToDelaunayMultipliers(final int[] dom) {
return new int[] {
dom[3],
dom[5],
dom[0] - dom[1] - dom[2] - dom[3] - dom[5],
dom[2] + dom[5],
dom[0] - dom[1] - dom[2] - dom[3] + dom[4] - dom[5]
};
}
/** Get the multipliers for Delaunay arguments (l, l', F, D, Ω).
* <p>
* Beware that for tides the multipliers for Delaunay arguments have an opposite
* sign with respect to the convention used for nutation computation! Here, we
* obey the tides convention.
* </p>
* @return multipliers for Delaunay arguments (l, l', F, D, Ω)
*/
public int[] getDelaunayMultipliers() {
return delaunayMultipliers.clone();
}
/** Get the multipliers for Doodson arguments (τ, s, h, p, N', ps).
* @return multipliers for Doodson arguments (τ, s, h, p, N', ps)
*/
public int[] getDoodsonMultipliers() {
return doodsonMultipliers.clone();
}
/** Get the Doodson number.
* @return Doodson number
*/
public int getDoodsonNumber() {
return doodsonNumber;
}
/** Get the multiplier for the τ Doodson argument.
* <p>
* This multiplier identifies semi-diurnal tides (2),
* diurnal tides (1) and long period tides (0)
* </p>
* @return multiplier for the τ Doodson argument
*/
public int getTauMultiplier() {
return doodsonMultipliers[0];
}
/** Get the phase of the tide.
* @param elements elements to use
* @return phase of the tide (radians)
*/
public double getPhase(final BodiesElements elements) {
return doodsonMultipliers[0] * elements.getGamma() -
delaunayMultipliers[0] * elements.getL() -
delaunayMultipliers[1] * elements.getLPrime() -
delaunayMultipliers[2] * elements.getF() -
delaunayMultipliers[3] * elements.getD() -
delaunayMultipliers[4] * elements.getOmega();
}
/** Get the angular rate of the tide.
* @param elements elements to use
* @return angular rate of the tide (radians/second)
*/
public double getRate(final BodiesElements elements) {
return doodsonMultipliers[0] * elements.getGammaDot() -
delaunayMultipliers[0] * elements.getLDot() -
delaunayMultipliers[1] * elements.getLPrimeDot() -
delaunayMultipliers[2] * elements.getFDot() -
delaunayMultipliers[3] * elements.getDDot() -
delaunayMultipliers[4] * elements.getOmegaDot();
}
@Override
public boolean equals(final Object object) {
if (object instanceof Tide) {
return doodsonNumber == ((Tide) object).doodsonNumber;
}
return false;
}
@Override
public int hashCode() {
return doodsonNumber;
}
}