src/org/math/plot/plots/VectorLayerPlot.java

package org.math.plot.plots;

import java.awt.*;

import javax.swing.*;

import org.math.plot.*;
import org.math.plot.render.*;
import org.math.plot.utils.*;

public class VectorLayerPlot extends LayerPlot {

        public static int RADIUS = 5;

        double[][] V;

        public VectorLayerPlot(Plot p, double[][] v) {
                super("Vector of " + p.name, p);
                if (v != null) {
                        Array.checkRowDimension(v, p.getData().length);
                        Array.checkColumnDimension(v, p.getData()[0].length);
                }
                V = v;

        }

        @Override
        public void setData(double[][] v) {
                V = v;
        }

        @Override
        public double[][] getData() {
                return V;
        }

        public void plot(AbstractDrawer draw, Color c) {
                if (!plot.visible)
                        return;

                draw.setColor(c);

                draw.setLineType(AbstractDrawer.CONTINOUS_LINE);

                for (int i = 0; i < plot.getData().length; i++) {
                        double[] d = Array.getRowCopy(plot.getData(), i);
                        for (int j = 0; j < d.length; j++) {
                                d[j] += V[i][j];
                        }
                        draw.drawLine(plot.getData()[i], d);
                        //TODO: draw arrow at position d

                }

        }

        public static void main(String[] args) {
                Plot2DPanel p2 = new Plot2DPanel();
                double[][] XYZ = new double[100][2];
                double[][] dXYZ = new double[100][2];

                for (int j = 0; j < XYZ.length; j++) {
                        XYZ[j][0] = Math.random()*10;
                        XYZ[j][1] = Math.random()*10;
                        dXYZ[j][0] = 1.0/Math.sqrt(1+Math.log(XYZ[j][0])*Math.log(XYZ[j][0]));
                        dXYZ[j][1] = Math.log(XYZ[j][0])/Math.sqrt(1+Math.log(XYZ[j][0])*Math.log(XYZ[j][0]));
                }
                p2.addScatterPlot("toto", XYZ);

                p2.addVectortoPlot(0, dXYZ);
                new FrameView(p2).setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        }
}

---