Hi Matthias, Let me explain a bit about what that final parameter is being used for. But first let me state that if you use circles to draw Venn diagrams, then for three or more circles there are many consistent set relationships that cannot be drawn accurately. An example of this is three equal size sets, A, B, C, where each set overlaps each other set by say 50%, but the intersection of A, B, C is zero. Using circles to draw this, the overlap of A^B^C won't show up in your diagram as zero. This is an example of a very common kind of relationship, and one that can't be drawn perfectly accurately using circles. So what the algorithm does for cases like this is try to come up with a layout that is "pretty good." Where "pretty good" means "not too misleading."
In a nutshell, the algorithm works like this: 1. Figure out the radius for A, B and C. 2. Figure out how far apart the center of A has to be from the center of B to satisfy the pair-wise constraint, and do the same for B & C, and A & C. 3. If distance relationships satisfy the triangle inequality, then it lays them out in a triangle, and then try to further improve the layout taking into account A^B^C by using an optimization technique to try to find a layout that is the least misleading. 4. If the distance relationships do not satisfy the triangle inequality, then the center of C is placed at the intersection of the edges of A and B and the stochastic hill climber is started. In these cases an "ideal" layout is much less likely to occur. Does this help explain what the final parameter is used for? Justin On Dec 10, 12:00 pm, Matthias Kluwe <[email protected]> wrote: > Hi! > > IMHO the seventh parameter of the data v set in cht=v seems to be > redundant. The sizes of the three circles are clearly fixed by the > first three parameters and their relative position by the parameters > four to six. > > It would be helpful for the user if the documentation mentioned > this... The last parameter for the should be optional, a mathematician > would say it should not exist. > > Regards, > Matthias --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Google Chart API" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/google-chart-api?hl=en -~----------~----~----~----~------~----~------~--~---
