R nls results different from those of Excel ??
Jeff Newmiller <jdnewmil <at> dcn.davis.ca.us> writes:
Excel definitely does not use nonlinear least squares fitting for power curve fitting. It uses linear LS fitting of the logs of x and y. There should be no surprise in the OP's observation.
May I be allowed to say that the general comments on MS Excel may be alright, in this special case they are not. The Excel Solver -- which is made by an external company, not MS -- has a good reputation for being fast and accurate. And it indeed solves least-squares and nonlinear problems better than some of the solvers available in R. There is a professional version of this solver, not available from Microsoft, that could be called excellent. We, and this includes me, should not be too arrogant towards the outside, non-R world, the 'barbarians' as the ancient Greeks called it. Hans Werner
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