Examples with NormalizedSphericalHarmonics org.orekit.forces.gravity.potential.NormalizedSphericalHarmonicsProvider.NormalizedSphericalHarmonics used on opensource projects

Example 6 with NormalizedSphericalHarmonics

use of org.orekit.forces.gravity.potential.NormalizedSphericalHarmonicsProvider.NormalizedSphericalHarmonics in project Orekit by CS-SI.

the class CachedNormalizedSphericalHarmonicsProviderTest method testInterpolation.

@Test
public void testInterpolation() throws OrekitException {
    // setup
    // generate points on grid with date as the origin
    cache.onDate(date);
    // sample at step/2
    AbsoluteDate sampleDate = date.shiftedBy(step / 2.0);
    // expected values
    NormalizedSphericalHarmonics expected = raw.onDate(sampleDate);
    // action
    NormalizedSphericalHarmonics actual = cache.onDate(sampleDate);
    // verify
    double tol = Precision.EPSILON;
    for (int n = 0; n < raw.getMaxDegree(); n++) {
        for (int m = 0; m < n; m++) {
            Assert.assertEquals(expected.getNormalizedCnm(n, m), actual.getNormalizedCnm(n, m), tol);
            Assert.assertEquals(expected.getNormalizedSnm(n, m), actual.getNormalizedSnm(n, m), tol);
        }
    }
}

Example 7 with NormalizedSphericalHarmonics

use of org.orekit.forces.gravity.potential.NormalizedSphericalHarmonicsProvider.NormalizedSphericalHarmonics in project Orekit by CS-SI.

the class EGMFormatReaderTest method testReadNormalized.

@Test
public void testReadNormalized() throws OrekitException {
    Utils.setDataRoot("potential");
    GravityFieldFactory.addPotentialCoefficientsReader(new EGMFormatReader("egm96_to5.ascii", true));
    NormalizedSphericalHarmonicsProvider provider = GravityFieldFactory.getNormalizedProvider(5, 5);
    NormalizedSphericalHarmonics harmonics = provider.onDate(AbsoluteDate.FUTURE_INFINITY);
    Assert.assertEquals(TideSystem.TIDE_FREE, provider.getTideSystem());
    Assert.assertEquals(0.957254173792E-06, harmonics.getNormalizedCnm(3, 0), 1.0e-15);
    Assert.assertEquals(0.174971983203E-06, harmonics.getNormalizedCnm(5, 5), 1.0e-15);
    Assert.assertEquals(0.0, harmonics.getNormalizedSnm(4, 0), 1.0e-15);
    Assert.assertEquals(0.308853169333E-06, harmonics.getNormalizedSnm(4, 4), 1.0e-15);
    Assert.assertEquals(-0.295301647654E-06, harmonics.getNormalizedCnm(5, 4), 1.0e-15);
    Assert.assertNull(provider.getReferenceDate());
    Assert.assertEquals(0, provider.getOffset(AbsoluteDate.J2000_EPOCH), Precision.SAFE_MIN);
    Assert.assertEquals(0, provider.getOffset(AbsoluteDate.MODIFIED_JULIAN_EPOCH), Precision.SAFE_MIN);
}

Example 8 with NormalizedSphericalHarmonics

use of org.orekit.forces.gravity.potential.NormalizedSphericalHarmonicsProvider.NormalizedSphericalHarmonics in project Orekit by CS-SI.

the class GRGSFormatReaderTest method testRegular05cNormalized.

@Test
public void testRegular05cNormalized() throws OrekitException {
    GravityFieldFactory.addPotentialCoefficientsReader(new GRGSFormatReader("grim5_C1.dat", true));
    NormalizedSphericalHarmonicsProvider provider = GravityFieldFactory.getNormalizedProvider(5, 5);
    Assert.assertEquals(TideSystem.UNKNOWN, provider.getTideSystem());
    AbsoluteDate refDate = new AbsoluteDate("1997-01-01T12:00:00", TimeScalesFactory.getTT());
    Assert.assertEquals(refDate, provider.getReferenceDate());
    AbsoluteDate date = new AbsoluteDate("2011-05-01T01:02:03", TimeScalesFactory.getTT());
    Assert.assertEquals(date.durationFrom(refDate), provider.getOffset(date), Precision.SAFE_MIN);
    double offset = date.durationFrom(refDate);
    double offsetYear = offset / Constants.JULIAN_YEAR;
    NormalizedSphericalHarmonics harmonics = provider.onDate(date);
    Assert.assertEquals(0.95857491635129E-06 + offsetYear * 0.28175700027753E-11, harmonics.getNormalizedCnm(3, 0), 1.0e-15);
    Assert.assertEquals(0.17481512311600E-06, harmonics.getNormalizedCnm(5, 5), 1.0e-15);
    Assert.assertEquals(0.0, harmonics.getNormalizedSnm(4, 0), 1.0e-15);
    Assert.assertEquals(0.30882755318300E-06, harmonics.getNormalizedSnm(4, 4), 1.0e-15);
    Assert.assertEquals(0.3986004415E+15, provider.getMu(), 0);
    Assert.assertEquals(0.6378136460E+07, provider.getAe(), 0);
}

Example 9 with NormalizedSphericalHarmonics

use of org.orekit.forces.gravity.potential.NormalizedSphericalHarmonicsProvider.NormalizedSphericalHarmonics in project Orekit by CS-SI.

the class ICGEMFormatReaderTest method testRegular05cNormalized.

@Test
public void testRegular05cNormalized() throws OrekitException {
    Utils.setDataRoot("potential");
    GravityFieldFactory.addPotentialCoefficientsReader(new ICGEMFormatReader("g007_eigen_05c_coef", false));
    NormalizedSphericalHarmonicsProvider provider = GravityFieldFactory.getNormalizedProvider(5, 5);
    Assert.assertEquals(TideSystem.TIDE_FREE, provider.getTideSystem());
    AbsoluteDate refDate = new AbsoluteDate("2004-10-01T12:00:00", TimeScalesFactory.getTT());
    Assert.assertEquals(refDate, provider.getReferenceDate());
    AbsoluteDate date = new AbsoluteDate("2013-01-08T10:46:53", TimeScalesFactory.getTT());
    NormalizedSphericalHarmonics harmonics = provider.onDate(date);
    Assert.assertEquals(date.durationFrom(refDate), provider.getOffset(date), Precision.SAFE_MIN);
    double offset = date.durationFrom(refDate);
    double offsetYear = offset / Constants.JULIAN_YEAR;
    Assert.assertEquals(0.957212879862e-06 + offsetYear * 0.490000000000e-11, harmonics.getNormalizedCnm(3, 0), 1.0e-15);
    Assert.assertEquals(0.174804558032e-06, harmonics.getNormalizedCnm(5, 5), 1.0e-15);
    Assert.assertEquals(0.0, harmonics.getNormalizedSnm(4, 0), 1.0e-15);
    Assert.assertEquals(0.308816581016e-06, harmonics.getNormalizedSnm(4, 4), 1.0e-15);
    Assert.assertEquals(0.3986004415E+15, provider.getMu(), 1.0e-20);
    Assert.assertEquals(0.6378136460E+07, provider.getAe(), 1.0e-20);
}

Example 10 with NormalizedSphericalHarmonics

use of org.orekit.forces.gravity.potential.NormalizedSphericalHarmonicsProvider.NormalizedSphericalHarmonics in project Orekit by CS-SI.

the class HolmesFeatherstoneAttractionModel method gradientHessian.

/**
 * Compute both the gradient and the hessian of the non-central part of the gravity field.
 * @param date current date
 * @param position position at which gravity field is desired in body frame
 * @param mu central attraction coefficient to use
 * @return gradient and hessian of the non-central part of the gravity field
 * @exception OrekitException if position cannot be converted to central body frame
 */
private GradientHessian gradientHessian(final AbsoluteDate date, final Vector3D position, final double mu) throws OrekitException {
    final int degree = provider.getMaxDegree();
    final int order = provider.getMaxOrder();
    final NormalizedSphericalHarmonics harmonics = provider.onDate(date);
    // allocate the columns for recursion
    double[] pnm0Plus2 = new double[degree + 1];
    double[] pnm0Plus1 = new double[degree + 1];
    double[] pnm0 = new double[degree + 1];
    double[] pnm1Plus1 = new double[degree + 1];
    double[] pnm1 = new double[degree + 1];
    final double[] pnm2 = new double[degree + 1];
    // compute polar coordinates
    final double x = position.getX();
    final double y = position.getY();
    final double z = position.getZ();
    final double x2 = x * x;
    final double y2 = y * y;
    final double z2 = z * z;
    final double r2 = x2 + y2 + z2;
    final double r = FastMath.sqrt(r2);
    final double rho2 = x2 + y2;
    final double rho = FastMath.sqrt(rho2);
    // cos(theta), where theta is the polar angle
    final double t = z / r;
    // sin(theta), where theta is the polar angle
    final double u = rho / r;
    final double tOu = z / rho;
    // compute distance powers
    final double[] aOrN = createDistancePowersArray(provider.getAe() / r);
    // compute longitude cosines/sines
    final double[][] cosSinLambda = createCosSinArrays(position.getX() / rho, position.getY() / rho);
    // outer summation over order
    int index = 0;
    double value = 0;
    final double[] gradient = new double[3];
    final double[][] hessian = new double[3][3];
    for (int m = degree; m >= 0; --m) {
        // compute tesseral terms
        index = computeTesseral(m, degree, index, t, u, tOu, pnm0Plus2, pnm0Plus1, pnm1Plus1, pnm0, pnm1, pnm2);
        if (m <= order) {
            // compute contribution of current order to field (equation 5 of the paper)
            // inner summation over degree, for fixed order
            double sumDegreeS = 0;
            double sumDegreeC = 0;
            double dSumDegreeSdR = 0;
            double dSumDegreeCdR = 0;
            double dSumDegreeSdTheta = 0;
            double dSumDegreeCdTheta = 0;
            double d2SumDegreeSdRdR = 0;
            double d2SumDegreeSdRdTheta = 0;
            double d2SumDegreeSdThetadTheta = 0;
            double d2SumDegreeCdRdR = 0;
            double d2SumDegreeCdRdTheta = 0;
            double d2SumDegreeCdThetadTheta = 0;
            for (int n = FastMath.max(2, m); n <= degree; ++n) {
                final double qSnm = aOrN[n] * harmonics.getNormalizedSnm(n, m);
                final double qCnm = aOrN[n] * harmonics.getNormalizedCnm(n, m);
                final double nOr = n / r;
                final double nnP1Or2 = nOr * (n + 1) / r;
                final double s0 = pnm0[n] * qSnm;
                final double c0 = pnm0[n] * qCnm;
                final double s1 = pnm1[n] * qSnm;
                final double c1 = pnm1[n] * qCnm;
                final double s2 = pnm2[n] * qSnm;
                final double c2 = pnm2[n] * qCnm;
                sumDegreeS += s0;
                sumDegreeC += c0;
                dSumDegreeSdR -= nOr * s0;
                dSumDegreeCdR -= nOr * c0;
                dSumDegreeSdTheta += s1;
                dSumDegreeCdTheta += c1;
                d2SumDegreeSdRdR += nnP1Or2 * s0;
                d2SumDegreeSdRdTheta -= nOr * s1;
                d2SumDegreeSdThetadTheta += s2;
                d2SumDegreeCdRdR += nnP1Or2 * c0;
                d2SumDegreeCdRdTheta -= nOr * c1;
                d2SumDegreeCdThetadTheta += c2;
            }
            // contribution to outer summation over order
            final double sML = cosSinLambda[1][m];
            final double cML = cosSinLambda[0][m];
            value = value * u + sML * sumDegreeS + cML * sumDegreeC;
            gradient[0] = gradient[0] * u + sML * dSumDegreeSdR + cML * dSumDegreeCdR;
            gradient[1] = gradient[1] * u + m * (cML * sumDegreeS - sML * sumDegreeC);
            gradient[2] = gradient[2] * u + sML * dSumDegreeSdTheta + cML * dSumDegreeCdTheta;
            hessian[0][0] = hessian[0][0] * u + sML * d2SumDegreeSdRdR + cML * d2SumDegreeCdRdR;
            hessian[1][0] = hessian[1][0] * u + m * (cML * dSumDegreeSdR - sML * dSumDegreeCdR);
            hessian[2][0] = hessian[2][0] * u + sML * d2SumDegreeSdRdTheta + cML * d2SumDegreeCdRdTheta;
            hessian[1][1] = hessian[1][1] * u - m * m * (sML * sumDegreeS + cML * sumDegreeC);
            hessian[2][1] = hessian[2][1] * u + m * (cML * dSumDegreeSdTheta - sML * dSumDegreeCdTheta);
            hessian[2][2] = hessian[2][2] * u + sML * d2SumDegreeSdThetadTheta + cML * d2SumDegreeCdThetadTheta;
        }
        // rotate the recursion arrays
        final double[] tmp0 = pnm0Plus2;
        pnm0Plus2 = pnm0Plus1;
        pnm0Plus1 = pnm0;
        pnm0 = tmp0;
        final double[] tmp1 = pnm1Plus1;
        pnm1Plus1 = pnm1;
        pnm1 = tmp1;
    }
    // scale back
    value = FastMath.scalb(value, SCALING);
    for (int i = 0; i < 3; ++i) {
        gradient[i] = FastMath.scalb(gradient[i], SCALING);
        for (int j = 0; j <= i; ++j) {
            hessian[i][j] = FastMath.scalb(hessian[i][j], SCALING);
        }
    }
    // apply the global mu/r factor
    final double muOr = mu / r;
    value *= muOr;
    gradient[0] = muOr * gradient[0] - value / r;
    gradient[1] *= muOr;
    gradient[2] *= muOr;
    hessian[0][0] = muOr * hessian[0][0] - 2 * gradient[0] / r;
    hessian[1][0] = muOr * hessian[1][0] - gradient[1] / r;
    hessian[2][0] = muOr * hessian[2][0] - gradient[2] / r;
    hessian[1][1] *= muOr;
    hessian[2][1] *= muOr;
    hessian[2][2] *= muOr;
    // convert gradient and Hessian from spherical to Cartesian
    final SphericalCoordinates sc = new SphericalCoordinates(position);
    return new GradientHessian(sc.toCartesianGradient(gradient), sc.toCartesianHessian(hessian, gradient));
}