BOXPLOT Display boxplots of a data sample.
    BOXPLOT(X) produces a box and whisker plot with one box for each column
    of X.  The boxes have lines at the lower quartile, median, and upper
    quartile values.  The whiskers are lines extending from each end of the
    boxes to show the extent of the rest of the data.  Outliers are data
    with values beyond the ends of the whiskers.