Hello. I am using the nonlinear least squares function (nls). The
function that I am trying to fit seems to be very sensitive to the
starting values and, if these are not chosen properly, the nls function
stops and gives an error message:
Error in numericDeriv(form[[3]], names(ind), env) :
Missing value or an Infinity produced when evaluating the model
In addition: Warning message:
NaNs produced in: sqrt((quantum.yeild * I + Amax)^2 - 4 * theta *
quantum.yeild *
I want to embed the nls function within a loop so that if it gives an
error message I can automatically adjust the starting value and retry.
To do this I have to be able to test if the function has converged
within the loop. I need something like an �if.error(fit)� function that
will return true if there has been an error. Does such a thing exist?
Bill Shipley
Associate Editor, Ecology
North American Editor, Annals of Botany
D�partement de biologie, Universit� de Sherbrooke,
Sherbrooke (Qu�bec) J1K 2R1 CANADA
[EMAIL PROTECTED]
<http://callisto.si.usherb.ca:8080/bshipley/>
http://callisto.si.usherb.ca:8080/bshipley/
[[alternative HTML version deleted]]
______________________________________________
[EMAIL PROTECTED] mailing list
https://www.stat.math.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
