Example usage for org.apache.commons.math3.analysis.interpolation HermiteInterpolator getPolynomials

Introduction

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

Prototype

public PolynomialFunction[] getPolynomials() throws NoDataException 

Source Link

Document

Compute the interpolation polynomials.

Usage

From source file:be.ugent.maf.cellmissy.analysis.singlecell.processing.impl.interpolation.TrackHermiteInterpolator.java

@Override
public InterpolatedTrack interpolateTrack(double[] time, double[] x, double[] y) {
    // create interpolators for X and Y
    HermiteInterpolator xHermite = new HermiteInterpolator();
    HermiteInterpolator yHermite = new HermiteInterpolator();
    int interpolationPoints = PropertiesConfigurationHolder.getInstance().getInt("numberOfInterpolationPoints");

    // create arrays to hold the interpolant time, the interpolated X and the interpolated Y
    double[] interpolantTime = new double[interpolationPoints];
    double[] interpolatedX = new double[interpolationPoints];
    double[] interpolatedY = new double[interpolationPoints];
    // the step used for the interpolation in both direction
    double interpolationStep = (time[time.length - 1] - time[0]) / interpolationPoints;

    // check for monotonicity
    boolean monotonic = MathArrays.isMonotonic(time, MathArrays.OrderDirection.INCREASING, false);
    // in case time is not monotonic, sort in place time, x and y coordinates
    if (!monotonic) {
        MathArrays.sortInPlace(time, x, y);
    }/*from   w  w  w. jav a 2 s  . com*/

    double[] internalPointsDerivativeX = internalPointsDerivative(time, x);
    double[] internalPointsDerivativeY = internalPointsDerivative(time, y);

    double[] endPointsDerivativeX = endPointsDerivative(time, x);
    double[] endPointsDerivativeY = endPointsDerivative(time, y);

    // call the interpolator and add sample points to it
    // we do add only the values, and not their derivatives
    for (int i = 0; i < time.length; i++) {
        if (i == 0) {
            xHermite.addSamplePoint(time[i], new double[] { x[i] }, new double[] { endPointsDerivativeX[0] });
            yHermite.addSamplePoint(time[i], new double[] { y[i] }, new double[] { endPointsDerivativeY[0] });
        } else if (i == time.length - 1) {
            xHermite.addSamplePoint(time[i], new double[] { x[i] }, new double[] { endPointsDerivativeX[1] });
            yHermite.addSamplePoint(time[i], new double[] { y[i] }, new double[] { endPointsDerivativeY[1] });
        } else {
            xHermite.addSamplePoint(time[i], new double[] { x[i] },
                    new double[] { internalPointsDerivativeX[i - 1] });
            yHermite.addSamplePoint(time[i], new double[] { y[i] },
                    new double[] { internalPointsDerivativeY[i - 1] });
        }
    }

    for (int i = 0; i < interpolationPoints; i++) {
        interpolantTime[i] = time[0] + (i * interpolationStep);
        interpolatedX[i] = xHermite.value(interpolantTime[i])[0];
        interpolatedY[i] = yHermite.value(interpolantTime[i])[0];
    }

    // get the polynomial functions in both directions
    PolynomialFunction polynomialFunctionX = xHermite.getPolynomials()[0];
    PolynomialFunction polynomialFunctionY = yHermite.getPolynomials()[0];

    return new InterpolatedTrack(interpolantTime, interpolatedX, interpolatedY, polynomialFunctionX,
            polynomialFunctionY);
}

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