eulerAPE: Drawing Area-Proportional 3-Venn Diagrams Using Ellipses
(A) The quantitative values in each region indicate the required region areas, for which an area-proportional 3-Venn diagram should be drawn. (B) The first step of the construction whereby the three accurate 2-Venn diagrams are drawn. (C) The second step of the construction whereby the identical copies of the circle labelled c are rotated such that they overlap completely and only one circle labelled c is visible. (D) The instance when only three circles are visible, such that the regions of the 3-Venn diagram are obtained. (E) The actual area of the regions in the constructed diagram D, which, as in most cases when these diagrams are drawn with circles, do not correspond to the desired values in A. The numeric label in each region of this diagram indicates the regions' actual area.