On Feb 4, 1:31 am, Eli Brosh <[email protected]> wrote: > I have a scanned digitized graph of a magnetic hysteresis loop. > That is, I have a list of points [(H0,B0),(H1,B1)....(Hn,Bn)] > however, the points are not ordered in any meaningful way. > In order to calculate the hysteresis loss, which is the area enclosed by the > loop, I need to somehow convert the list of points into a polyngon > (clockwise or counterclockwise).
Hmm, that's an interesting problem. Since you know the physical process, how about treating this as a curve fitting exercise, trying to find the hysteresis curve which best fits the data in (say) the least orthogonal squares sense. I am assuming that a hysteresis curve has some well-known parametrization. Just minimize the goodness of fit over the free parameters of the curve. (Treating the endpoints as free parameters is probably going to complicate it, but that's only a practical problem.) I am assuming that for given parameters, it is easy to compute the area inside the loop. As a bonus you'll get estimates of the physical parameters which might be interesting in themselves. Take a look at Seber & Wild, "Nonlinear Regression". Dunno if such a problem is in there but you might get some inspiration. good luck Robert Dodier -- 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/sage-support URL: http://www.sagemath.org
