What am I failing to understand here?
The script below works fine if the dataset being used is
DNase1 <- DNase[ DNase$Run == 1, ] per the example given in
help(nlrob).
Obviously, I am trying to understand how to use nls and nlrob to fit
curves to data using R.
#package=DAAG
attach(codling)
plot(pobs~dose)
#next command returns 'step factor reduced below min factor error'
m.nls <- nls( pobs ~ a/(1 + exp(( b - log(dose) )/c ) ),
data = codling,
start = list( a = 3, b = 0, c = 1 ),
trace = TRUE )
s<-seq(min(pobs), max(pobs), .01)
p.nls<-predict(m.nls,list(pobs=s))
lines(s,p.nls,col='blue') #generates 'x and y lengths differ' error
Gregory A. Graves, Lead Scientist
Everglades REstoration COoordination and VERification (RECOVER)
Restoration Sciences Department
South Florida Water Management District
Phones: DESK: 561 / 682 - 2429
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