Hi On 11/06/2008 at 10:56 a.m., "Ranney, Steven" <[EMAIL PROTECTED]> wrote: > I'm tyring to fit a relatively simple nls model to some data, but keep coming > up against the same error (code follows): > > Oto=nls(Otolith ~ Linf*(1-exp(-k(AGE-to))), > data = ages, > start = list(Linf=1000, k=0.1, to=0.1), > trace = TRUE) > > The error message I keep getting is "Error in eval(expr, envir, enclos) : > could not find function "k"". I've used this line of code for other nls > models (with different data, parameter estimates, etc.), but have never > gotten this error. The data is > > AGE,Otolith,Scale > 1,207.1052632,207.1052632 > 2,329.962963,332.7586207 > 3,401.9473684,406 > 4,422,413.1111111 > 5,452.6785714,458.34375 > 6,510.75,533 > 7,477,674 > 8,643,704 > 9,,615 > 10,695.5, > 12,615, > > Are the missing values (e.g., no value for Otolith, AGE 9) having an effect? > I am using Tinn-R as an editor > > I'm new to R, trying to get away from Rcmdr (though it has been helpful), > and still trying to learn the language with the aid of several books on the > R. A search of the R Archive did not prove fruitful. > > Thanks in advance, > > SR > > Steven H. Ranney
You've made a typo. Check out the formula you passed to nls -- you forget to include a "*" after k. What I think you want is something like Oto <- nls(Otolith ~ Linf * (1 - exp(-k * (AGE - t0) ) ), ...) Cheers, Michael
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