[R] question about model formula
Michael A. Miller
mmiller3 at iupui.edu
Thu Mar 6 19:32:40 CET 2003
Dear R Gang,
I'm interested in using R and the nls package for fitting kinetic
models. I'm having some difficulty getting a model specified for
nls though. The math for the model that I want to fit is
dg(t)/dt = K1 f(t) - k2 g(t)
where g(t) and f(t) are measured data at a sequence of times t.
K1 and k2 are the parameters of the model. If I solve this, the
g(t) = K1 \int_0^t f(t') \exp(-k2(t-t')) dt'
and I'm not sure how to write a formula in R that I can pass to
nls that will handle both the implicit loop over the data values
of t and the interpolation and numeric integration over t'.
Can anyone help me to get this properly coded for R?
Michael A. Miller mmiller3 at iupui.edu
Imaging Sciences, Department of Radiology, IU School of Medicine
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