Java 平线代替波浪
我想画一个正弦波,但我的应用程序生成一条平线。当我使用带有random fromJava 平线代替波浪,java,jfreechart,trigonometry,Java,Jfreechart,Trigonometry,我想画一个正弦波,但我的应用程序生成一条平线。当我使用带有random fromjchartfree示例的系列时,一切都很好。我还使用调试器检查值是否正确。值不同于零 public void createDataset() { XYSeriesCollection dataset = new XYSeriesCollection(); XYSeries series1 = new XYSeries("Object 1"); double A = 1;
jchartfree
示例的系列时,一切都很好。我还使用调试器检查值是否正确。值不同于零
public void createDataset() {
XYSeriesCollection dataset = new XYSeriesCollection();
XYSeries series1 = new XYSeries("Object 1");
double A = 1;
double T = 1;
double Fs = 10;
double f = 200;
int rozmiar = (int) (T*Fs);
double[] x = new double[rozmiar];
for (int i = 0; i < rozmiar; i++)
{
x[i] = A * Math.sin(2 * Math.PI * f * i / Fs);
series1.add(i, x[i]);
}
dataset.addSeries(series1);
data = dataset;
}
//...
public void createChartPanel() {
//pWykres = new JPanel();
//if(java.util.Arrays.asList(getComponents()).contains(pWykres)){
//getContentPane().remove(pWykres);
//}
if(pWykres != null){
pWykres.removeAll();
pWykres.revalidate();
}
String chartTitle = "Objects Movement Chart";
String xAxisLabel = "X";
String yAxisLabel = "Y";
JFreeChart chart = ChartFactory.createXYLineChart(chartTitle,
xAxisLabel, yAxisLabel, dataset);
customizeChart(chart);
pWykres = new ChartPanel(chart);
getContentPane().add(pWykres, BorderLayout.CENTER);
setSize(620, 460);
//validate();
pWykres.repaint();
}
//endregion
//...
//region
private void customizeChart(JFreeChart chart) {
XYPlot plot = chart.getXYPlot();
XYSplineRenderer renderer;
renderer = new XYSplineRenderer();
renderer.setSeriesShapesVisible(0, false);
// sets paint color for each series
renderer.setSeriesPaint(0, Color.RED);
// sets thickness for series (using strokes)
renderer.setSeriesStroke(0, new BasicStroke(1.0f));
// sets paint color for plot outlines
//plot.setOutlinePaint(Color.BLUE);
//plot.setOutlineStroke(new BasicStroke(2.0f));
// sets renderer for lines
plot.setRenderer(renderer);
// sets plot background
plot.setBackgroundPaint(Color.WHITE);
// sets paint color for the grid lines
plot.setRangeGridlinesVisible(true);
plot.setRangeGridlinePaint(Color.BLACK);
plot.setDomainGridlinesVisible(true);
plot.setDomainGridlinePaint(Color.BLACK);
}
public void createDataset(){
XYSeriesCollection数据集=新的XYSeriesCollection();
XYSeries系列1=新的XYSeries(“对象1”);
双A=1;
双T=1;
双Fs=10;
双f=200;
int rozmiar=(int)(T*Fs);
double[]x=新的double[rozmiar];
对于(int i=0;i
您使用的正弦值始终是2*PI的整数倍,因此所有这些值都将(近似)为零,因此图形将最终显示为平面,除非缩放以显示这些微小值(仅为浮点错误)
其中A
=1和f/Fs
=20和i
为整数
例如:
Math.sin(0) // 0.0
Math.sin(2 * Math.PI) // -2.4492935982947064E-16 (approximately zero)
Math.sin(4 * Math.PI) // -4.898587196589413E-16 (approximately zero)
要查看正弦波的特征形状,您需要以更小的增量改变sin
函数的输入,例如pi/10或更小。您是对的。我没有注意到。我在处理旧C#代码中的公式时犯了错误。我刚刚从公式中删除了f,从现在起一切都很好。
Math.sin(0) // 0.0
Math.sin(2 * Math.PI) // -2.4492935982947064E-16 (approximately zero)
Math.sin(4 * Math.PI) // -4.898587196589413E-16 (approximately zero)