I'm trying the different parameters, but don't know what the error is: Error in nlsModel(formula, mf, start, wts) : singular gradient matrix at initial parameter estimates
Thanks for any suggestions. On Tue, Jun 20, 2017 at 7:37 PM, Don Cohen <don-r-h...@isis.cs3-inc.com> wrote: > > If you know the period and want to fit phase and amplitude, this is > equivalent to fitting a * sin + b * cos > > > >>> > I don't know how to set the approximate starting values. > > I'm not sure what you meant by that, but I suspect it's related to > phase and amplitude. > > > >>> > Besides, does the method work for sine curve as well? > > sin is the same as cos with a different phase > Any combination of a and b above = c * sin (theta + d) for > some value of c and d and = e * cos (theta + f) for some value > of e and f. > Also for any c,d and for any e,f there is an a,b. > the c and e are what I'm calling amplitude, the d and f are what > I'm calling phase. > [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.