[R] Multiple logistic curves
danbebber at forestecology.co.uk
Mon Aug 16 17:23:06 CEST 2004
Apologies, I have sent this message before but received no replies so I'm
trying again just in case...
Motivated by the discovery of 'loglet analysis'
(http://phe.rockefeller.edu/LogletLab/) that allows decomposition of growth
curves into a series of logistic equations, I attempted to do the same thing
Time <- 1:200
pop.size <- SSlogis(Time,10,20,5) + SSlogis(Time,20,100,20) +
results <- nls(pop.size ~ SSlogis(Time, Asym1, xmid1, scal1) + SSlogis(Time,
Asym2, xmid2, scal2),
start = list(Asym1=5, xmid1=15, scal1=30, Asym2=25, xmid2=60, scal2=25))
I get the error message:
Error in nls(size ~ SSlogis(Time, Asym1, xmid1, scal1) + SSlogis(Time, :
step factor 0.000488281 reduced below `minFactor' of 0.000976563
Any hints in making this analysis work would be greatly appreciated.
Dr. Daniel P. Bebber
Department of Plant Sciences
University of Oxford
South Parks Road
Tel. 01865 275060
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