NaN based implementation: #ifndef PLOTCURVE_H #define PLOTCURVE_H #include <qwt_plot_curve.h> class PlotCurve : public QwtPlotCurve { public: PlotCurve() {} virtual ~PlotCurve() {} protected: virtual void drawCurve(QPainter *p, int style, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasRect, int from, int to) const override { const QwtSeriesData<QPointF> * series = data(); int from_ = from; int to_ = from; bool lineStarted = false; for (int i = from; i <= to; ++i) { const QPointF...