code: public static PlotCanvas plot(double[] x, double[] y) {
          double[] lowerBound = {Math.min(x), Math.min(y)};
          double[] upperBound = {Math.max(x), Math.max(y)};
          PlotCanvas canvas = new PlotCanvas(lowerBound, upperBound);
          canvas.add(new QQPlot(x, y));
          return canvas;
      }
docs: Create a plot canvas with the two sample Q-Q plot.
  The x-axis is the quantiles of x and the y-axis is the quantiles of y.
  @param x a sample set.
  @param y a sample set.