Example usage for org.apache.commons.math3.analysis.interpolation FieldHermiteInterpolator addSamplePoint

Introduction

In this page you can find the example usage for org.apache.commons.math3.analysis.interpolation FieldHermiteInterpolator addSamplePoint.

Prototype

public void addSamplePoint(final T x, final T[]... value)
        throws ZeroException, MathArithmeticException, DimensionMismatchException, NullArgumentException 

Source Link

Document

Add a sample point.

Usage

From source file:org.orekit.utils.TimeStampedFieldPVCoordinates.java

/** Interpolate position-velocity.
 * <p>//from  w w w . j  a  va2 s .c  o m
 * The interpolated instance is created by polynomial Hermite interpolation
 * ensuring velocity remains the exact derivative of position.
 * </p>
 * <p>
 * Note that even if first time derivatives (velocities)
 * from sample can be ignored, the interpolated instance always includes
 * interpolated derivatives. This feature can be used explicitly to
 * compute these derivatives when it would be too complex to compute them
 * from an analytical formula: just compute a few sample points from the
 * explicit formula and set the derivatives to zero in these sample points,
 * then use interpolation to add derivatives consistent with the positions.
 * </p>
 * @param date interpolation date
 * @param filter filter for derivatives from the sample to use in interpolation
 * @param sample sample points on which interpolation should be done
 * @param <T> the type of the field elements
 * @return a new position-velocity, interpolated at specified date
 */
@SuppressWarnings("unchecked")
public static <T extends RealFieldElement<T>> TimeStampedFieldPVCoordinates<T> interpolate(
        final AbsoluteDate date, final CartesianDerivativesFilter filter,
        final Collection<TimeStampedFieldPVCoordinates<T>> sample) {

    // get field properties
    final T prototype = sample.iterator().next().getPosition().getX();
    final T zero = prototype.getField().getZero();

    // set up an interpolator taking derivatives into account
    final FieldHermiteInterpolator<T> interpolator = new FieldHermiteInterpolator<T>();

    // add sample points
    switch (filter) {
    case USE_P:
        // populate sample with position data, ignoring velocity
        for (final TimeStampedFieldPVCoordinates<T> datedPV : sample) {
            final FieldVector3D<T> position = datedPV.getPosition();
            interpolator.addSamplePoint(zero.add(datedPV.getDate().durationFrom(date)), position.toArray());
        }
        break;
    case USE_PV:
        // populate sample with position and velocity data
        for (final TimeStampedFieldPVCoordinates<T> datedPV : sample) {
            final FieldVector3D<T> position = datedPV.getPosition();
            final FieldVector3D<T> velocity = datedPV.getVelocity();
            interpolator.addSamplePoint(zero.add(datedPV.getDate().durationFrom(date)), position.toArray(),
                    velocity.toArray());
        }
        break;
    case USE_PVA:
        // populate sample with position, velocity and acceleration data
        for (final TimeStampedFieldPVCoordinates<T> datedPV : sample) {
            final FieldVector3D<T> position = datedPV.getPosition();
            final FieldVector3D<T> velocity = datedPV.getVelocity();
            final FieldVector3D<T> acceleration = datedPV.getAcceleration();
            interpolator.addSamplePoint(zero.add(datedPV.getDate().durationFrom(date)), position.toArray(),
                    velocity.toArray(), acceleration.toArray());
        }
        break;
    default:
        // this should never happen
        throw new OrekitInternalError(null);
    }

    // interpolate
    final T[][] p = interpolator.derivatives(zero, 2);

    // build a new interpolated instance
    return new TimeStampedFieldPVCoordinates<T>(date, new FieldVector3D<T>(p[0]), new FieldVector3D<T>(p[1]),
            new FieldVector3D<T>(p[2]));

}

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