/* Copyright 2002-2017 CS Systèmes d'Information
* Licensed to CS Systèmes d'Information (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,
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package org.orekit.estimation.measurements;
import java.util.List;
import org.hipparchus.stat.descriptive.rank.Median;
import org.hipparchus.util.FastMath;
import org.junit.Assert;
import org.junit.Test;
import org.orekit.errors.OrekitException;
import org.orekit.estimation.Context;
import org.orekit.estimation.EstimationTestUtils;
import org.orekit.estimation.EstimationUtils;
import org.orekit.estimation.StateFunction;
import org.orekit.orbits.OrbitType;
import org.orekit.orbits.PositionAngle;
import org.orekit.propagation.Propagator;
import org.orekit.propagation.SpacecraftState;
import org.orekit.propagation.conversion.NumericalPropagatorBuilder;
import org.orekit.time.AbsoluteDate;
public class PVTest {
@Test
public void testStateDerivatives() throws OrekitException {
Context context = EstimationTestUtils.eccentricContext();
final NumericalPropagatorBuilder propagatorBuilder =
context.createBuilder(OrbitType.KEPLERIAN, PositionAngle.TRUE, true,
1.0e-6, 60.0, 0.001);
// create perfect range measurements
final Propagator propagator = EstimationTestUtils.createPropagator(context.initialOrbit,
propagatorBuilder);
final List<ObservedMeasurement<?>> measurements =
EstimationTestUtils.createMeasurements(propagator,
new PVMeasurementCreator(),
1.0, 3.0, 300.0);
propagator.setSlaveMode();
double[] errorsP = new double[3 * 6 * measurements.size()];
double[] errorsV = new double[3 * 6 * measurements.size()];
int indexP = 0;
int indexV = 0;
for (final ObservedMeasurement<?> measurement : measurements) {
final AbsoluteDate date = measurement.getDate();
final SpacecraftState state = propagator.propagate(date);
final double[][] jacobian = measurement.estimate(0, 0, state).getStateDerivatives();
// compute a reference value using finite differences
final double[][] finiteDifferencesJacobian =
EstimationUtils.differentiate(new StateFunction() {
public double[] value(final SpacecraftState state) throws OrekitException {
return measurement.estimate(0, 0, state).getEstimatedValue();
}
}, measurement.getDimension(), OrbitType.CARTESIAN,
PositionAngle.TRUE, 1.0, 3).value(state);
Assert.assertEquals(finiteDifferencesJacobian.length, jacobian.length);
Assert.assertEquals(finiteDifferencesJacobian[0].length, jacobian[0].length);
for (int i = 0; i < jacobian.length; ++i) {
for (int j = 0; j < jacobian[i].length; ++j) {
final double relativeError = FastMath.abs((finiteDifferencesJacobian[i][j] - jacobian[i][j]) /
finiteDifferencesJacobian[i][j]);
if (j < 3) {
errorsP[indexP++] = relativeError;
} else {
errorsV[indexV++] = relativeError;
}
}
}
}
// median errors
Assert.assertEquals(0.0, new Median().evaluate(errorsP), 2.1e-10);
Assert.assertEquals(0.0, new Median().evaluate(errorsV), 2.1e-10);
}
}