Area plot of cummulative sum of the columns of y. This shows the contributions of a value to a sum, and is functionally similar to
plot (x, cumsum (y, 2)), except that the area under the curve is shaded.If the x argument is ommitted it is assumed to be given by
1 : rows (y). A value lvl can be defined that determines where the base level of the shading under the curve should be defined.Additional arguments to the
areafunction are passed to thepatch. The optional return value h provides a handle to area series object representing the patches of the areas.