java - Flat line instead wave -

i want plot sine wave, instead application generates flat line. when use series random jchartfree example works fine. use debugger check if values good. values different zero

public void createdataset() {     xyseriescollection dataset = new xyseriescollection();     xyseries series1 = new xyseries("object 1");      double = 1;                            double t = 1;                            double fs = 10;                        double f = 200;                          int rozmiar = (int) (t*fs);      double[] x = new double[rozmiar];     (int = 0; < rozmiar; i++)    {         x[i] = * math.sin(2 * math.pi * f * / 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 each series     renderer.setseriespaint(0, color.red);      // sets thickness series (using strokes)     renderer.setseriesstroke(0, new basicstroke(1.0f));      // sets paint color plot outlines     //plot.setoutlinepaint(color.blue);     //plot.setoutlinestroke(new basicstroke(2.0f));      // sets renderer lines     plot.setrenderer(renderer);      // sets plot background     plot.setbackgroundpaint(color.white);      // sets paint color grid lines     plot.setrangegridlinesvisible(true);     plot.setrangegridlinepaint(color.black);      plot.setdomaingridlinesvisible(true);     plot.setdomaingridlinepaint(color.black); } 

you taking sine of values whole multiples of 2 * pi, of these values (approximately) zero, hence graph end appearing flat unless scaled show these tiny values (which floating point errors).

x[i] = * math.sin(2 * math.pi * f * / fs); 

where a = 1 , f/fs = 20 , i integer

for example:

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) 

to see characteristic shape of sine wave, need vary input sin function smaller increments, e.g. pi/10 or less.