title: Drawing smooth curve with Qt C++
body: <p>I have a set of points to plot and their coordinates are stored in </p>
  
  <pre><code>QVector&lt;double&gt; x(200), y(200);
  </code></pre>
  
  <p>I'd like to connect them with some smooth curve, any, say, splines. Or a bigger array of points between knots would also suffice. My try is</p>
  
  <pre><code>    customPlot-&gt;addGraph();
      customPlot-&gt;graph(0)-&gt;setData(x, y);
      customPlot-&gt;graph(0)-&gt;setPen(QPen(Qt::blue));
      customPlot-&gt;xAxis-&gt;setLabel("Index");
      customPlot-&gt;yAxis-&gt;setLabel("Amplitude");
      customPlot-&gt;xAxis-&gt;setRange(0, 200);
      customPlot-&gt;yAxis-&gt;setRange(-3, 3);
  </code></pre>
  
  <p>I tried QPainterPath class, but it didn't work. Please, help me out.</p>
  
  <p>UPD: I'm now looking through QEasingCurve class, these functions might help, but authors provide no examples and I don't know how to use them.</p>