R help - Jul 2005 - look for help on nlm in R

Hi, 
	I had a hard time in learning nlm in R and appreciate any help. 
	I encounted the following error message from time to time when I tried
different starting parameter values (three parameter values in this case) in
nlm(f=SS.fun,p=c(0.1/40,0.1,2),hessian = FALSE,N.measure=object,h=20)
	Error in f(x, ...) : only 0's may mix with negative subscripts 
	Basically I know the three parameter values should all be positive numbers. So,
how to select appropriate starting parameter values to prevent this kind of
error message?
	Thanks much 
	Sincerely, 
	Maggie Zhu


This communication is for use by the intended recipient and ...{{dropped}}

>>>>> "MaggieZ" == Zhu, Maggie <maggie.zhu at
pioneer.com>
>>>>>     on Thu, 7 Jul 2005 14:40:37 -0500 writes:
    MaggieZ> I had a hard time in learning nlm in R and appreciate any help. 

    MaggieZ> I encounted the following error message from time
    MaggieZ> to time when I tried different starting parameter
    MaggieZ> values (three parameter values in this case) in

     >>  nlm(f=SS.fun,p=c(0.1/40,0.1,2),hessian =
FALSE,N.measure=object,h=20)

     Error in f(x, ...) : only 0's may mix with negative subscripts 

    MaggieZ> Basically I know the three parameter values should all be
positive numbers. So, how to select appropriate starting parameter values to
prevent this kind of error message?

Maggie, it's a bug in the 'SS.fun' function that you are asking
nlm() to minimize.  So it would be best to show us your
SS.fun().

BTW:  "subscripts" are the `` i ''  in  x[i]
      in its the subscripts that become wrong in your SS.fun function.

Regards,
Martin Maechler, ETH Zurich