docs: public static void fillWidth(double x0, double y0, double derivateX, double derivateY, double width, PlotOperator plot)
      {
          double halfWidth = width/2.0;
          if (Math.abs(derivateY) <= Double.MIN_VALUE)
          {
              drawLine((int)(x0), (int)(y0+halfWidth), (int)(x0), (int)(y0-halfWidth), plot);
          }
          else
          {
              double s = derivateX/-derivateY;
              double w2 = halfWidth*halfWidth;
              double x1 = Math.sqrt(w2/(s*s+1));
              double y1 = s*x1;
              drawLine((int)(x0+x1), (int)(y0+y1), (int)(x0-x1), (int)(y0-y1), plot);
          }
      }