Hello. Following pages 342-347 of Pinheiro & Bates, I am trying to
write a self-starting nonlinear function (a non-rectagular hyperbola) to
be used in nonlinear least squares regression (and eventually for a
mixed model). When I use the getInitial function for my self-starting
function I get the following error message:
> getInitial(photo~NRhyperbola(Irr,theta,Am,alpha,Rd),dat)
Error in tapply(y, x, mean, na.rm = TRUE) :
arguments must have same length
Since I do not explicitly call tapply in my function that makes
NRhyperbola a self-starting function (called NRhyperbolaInit, see
below), I assume that the error is coming from within the mCall function
but I can't figure out where or how.
Would someone who has successfully done this be willing to look at my
code and see where the problem arises?
> NRhyperbolaInit
function(mCall,LHS,data)
{
xy<-sortedXyData(mCall[["x"]],LHS,data)
if(nrow(xy)<3){
stop("Too few unique irradiance values")
}
theta<-0.75
Rd<-min(xy[,"y"])
Am<-max(xy[,"y"]) + abs(Rd)
if(sum(xy[,"x"]<50)>3)alpha<-coef(lm(y~x,data=xy,subset=x<50))[2]
if(sum(xy[,"x"]<50)<=3)alpha<-0.07
value<-c(theta,Am,alpha,Rd)
names(value)<-mCall[c("theta","Am","alpha","Rd")]
value
}
Bill Shipley
[EMAIL PROTECTED]
<http://callisto.si.usherb.ca:8080/bshipley/>
http://callisto.si.usherb.ca:8080/bshipley/
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