using lsoda() and nls() together

Thanks to Dieter Menne and Spencer Graves I started to get my way through
lsoda()
Now I need to use it in with nls() to assess parameters

I have a go with a basic example

dy/dt = K1*conc

I try to assess the value of K1 from a simulated data set with a K1 close to
2.
Here is (I think) the best code that I've done so far even though it crashes
when I call nls()

--------------------------------------------------------------
x<-seq(0,10,,100)
y<-exp(2*x)
y<-rnorm(y,y,0.3*y)

test.model<-function(t,conc,parms){
	dy.dt = parms["K1"]*conc
	list(dy.dt)
	}

require(deSolve)
foo<-lsoda(c(conc=1),times=seq(0,10,,100),test.model,parms=c(K1=2))
foo
#####################use of nls

func<-function(K1) {
	foo<-lsoda(c(conc=1),times=seq(0,10,,100),test.model,parms=c(K1=K1))
	foo[,"conc"]
	}
nls(foo~func(K1),start=list(K1=1),data=data.frame(foo=y))

##################### have a look on the SSD ##################### y is the
vector of real data
SSD<-function(K1) {
	sum((y-func(K1))^2)
	}
data<-seq(1.5,2.1,,100)
plot(data,sapply(data,SSD),type="l")
--------------------------------------------------------------

Regards/Cordialement

Benoit Boulinguiez 

-----Message d'origine-----
De : spencerg [mailto:spencer.graves at prodsyse.com] 
Envoy? : vendredi 15 mai 2009 05:28
? : Benoit Boulinguiez
Cc : dieter.menne at menne-biomed.de; r-help at r-project.org
Objet : Re: [R] ode first step

      Have you looked at the vignette in the deSolve package? 

           (deS <- vignette('compiledCode')) # opens a "pdf" file
           Stangle(deS$file) # writes an R script file to "getwd()" 

      In spite of the name, this vignette includes an example entirely in R.
By comparing it with your code, I see that you do NOT provide a connection
between y, parms, K1, C0, m, V, K2 and q.  Something like the following
might work: 

kinetic.model<-function(t,y,parms){
	dq.dt = parms['K1']*y['C0'] - (parms['K1']*y['m']/y['V']+
parms['K2'])*y['q']
	list(dq.dt)
	}

      This may not be correct, but I hope the changes will help you see how
to make it work. 

      Bon Chance. 
      Spencer Graves