Example: SplineData Chart

import com.imsl.math.*;
import com.imsl.chart.*;
import com.imsl.stat.Random;
import java.awt.Color;


public class SplineDataEx1 extends javax.swing.JApplet {
    static private final int nData = 21;
    static private final int nSpline = 100;
    
    private JPanelChart panel;
    
    public void init() {
        Chart chart = new Chart(this);
        panel = new JPanelChart(chart);
        getContentPane().add(panel, java.awt.BorderLayout.CENTER);
        setup(chart);
    }
    
    static private void setup(Chart chart) {
        chart.getChartTitle().setTitle(new Text("Smoothed Spline"));
        
        Legend legend = chart.getLegend();
        legend.setTitle(new Text("Legend"));
        legend.setViewport(0.7, 0.9, 0.1, 0.3);
        legend.setPaint(true);

        // Original data
        double xData[] = grid(nData);
        double yData[] = new double[nData];
        for (int k = 0;  k < nData;  k++) {
            yData[k] = f(xData[k]);
        }
        AxisXY axis = new AxisXY(chart);
        Data data = new Data(axis, xData, yData);
        data.setDataType(data.DATA_TYPE_MARKER);
        data.setMarkerType(Data.MARKER_TYPE_HOLLOW_CIRCLE);
        data.setMarkerColor(Color.red);
        data.setTitle("Original Data");
        
        // Noisy data
        Random random = new Random(123457);
        double yNoisy[] = new double[nData];
        for (int k = 0;  k < nData;  k++) {
            yNoisy[k] = yData[k] + (2.*random.nextDouble()-1.);
        }
        data = new Data(axis, xData, yNoisy);
        data.setDataType(data.DATA_TYPE_MARKER);
        data.setMarkerType(Data.MARKER_TYPE_FILLED_SQUARE);
        data.setMarkerSize(0.75);
        data.setMarkerColor(Color.blue);
        data.setTitle("Noisy Data");
        
        chartSpline(axis, new CsSmooth(xData, yData), Color.red, "CsSmooth");
        chartSpline(axis, new CsSmoothC2(xData, yData, nData),
            Color.orange, "CsSmoothC2");
    }
    
    
    static private void chartSpline(AxisXY axis, Spline spline,
    Color color, String title) {
        Data data = new SplineData(axis, spline);
        data.setDataType(data.DATA_TYPE_LINE);
        data.setLineColor(color);
        data.setTitle(title);
    }
    
    
    static private double[] grid(int nData) {
        double xData[] = new double[nData];
        for (int k = 0;  k < nData;  k++) {
            xData[k] = 3.0*k / (double)(nData-1);
        }
        return xData;
    }
    
    static private double f(double x) {
        return 1.0/(0.1+Math.pow(3.0*(x-1.0),4));
    }
    
    
    public static void main(String argv[]) {
        JFrameChart frame = new JFrameChart();
        SplineDataEx1.setup(frame.getChart());
        frame.show();
    }
}

Output

Link to Java source.