Jonas Stein <news <at> jonasstein.de> writes: > > i have a list of values like this > > x y > 1 3 > 2 2
[snip] > > and need the inflexion points (and all max and min). > Is there a nice way to get the local max, min and inflexion points? diff(y) gives you the first difference, the analogue of the gradient diff(diff(y)) gives the second difference, the analogue of the second derivative. dy <- diff(y) d2y <- diff(dy) which(dy==0) ## critical values sign(s2y)[which(dy==0)] ## test for max/min/saddle which(d2y==0) ## inflection points ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
