Displaying 2 results from an estimated 2 matches for "mitscherlich".
2004 Jul 16
1
specifying a function in nls
...all. Here is the context.
1. If I specify the following command, it works fine:
> fit2<-nls(
+ A~Am*(1-exp(-alpha*(I-LCP))),data=dat1,
+ start=list(Am=3.6,alpha=0.01,LCP=20))
2. Now, I want to be able to specify the function definition
outside of nls. I do the following:
> Mitscherlich<-function(Am,alpha,I,LCP,...){
Am*(1-exp(-alpha*(I-LCP)))
}
and then:
> fit3<-nls(
+ A~Mitscherlich,data=dat1,
+ start=list(Am=2.7,alpha=0.006,LCP=45))
and I get the error message: Error in lhs - rhs : non-numeric argument
to binary operator
What am I doing wrong?
Than...
2003 Feb 04
0
Help with NLME
I am relatively new to NLME, so the solution to the problem I describe here
may be obvious. But I've spent several days trying to get the right syntax
to formulate random effects for this model appropriately. The full model is:
nlme(a ~ a.mitscherlich(a.qe, a.max, lcp, light),
data=light,
fixed = a.max + a.qe + lcp ~ trt,
random = a.max + a.qe + lcp ~ 1 | bench/line,
start = list(fixed=c(17.4305, 0.182444, 0.00928341, -0.00057221,
44.8384, 8.67678)),
method="ML", verbose=T,...