ili coordinates of peak points
http://www.freepatentsonline.com/5131155.html
An apparatus as set forth in claim 3, wherein the third means includes thirteenth means, when the previous value of R is equal to or larger than the other predetermined value, for receiving peak point coordinates (Px, Py) and reference point coordinates (Kx, Ky) and calculating a peak quantity and peak direction using the following equations:

http://www1.hollins.edu/depts/math/hammer/coaster/coastercub...
Enter the x coordinates of your n peak point and valley point using the list syntax ( [x1,x2,...,xn] ) for the xdata variable.