st: nonlinear least squares

[Henrik Andersson <henrik.andersson@tft.lth.se>]

Hi,

I am having problem using nonlinear least squares. It seems to work when I 
do the programming, I do not get any "error message" when running the 
funtion that I have programmed. The problem occure when I try to estimate 
the function.  I even have used one of the examples from the "reference 
guide" to see if it was my function that was the problem, but the result is 
the same, I get an error message. My programming for the example from the 
book looks like, where x is my dependent varialbe:

program define nltest
        version 7.0
        if "`1´" == "?" {
                global S_1 "B0 B1"
                global B0=1
                global B1=.1
                exit
        }
        replace `1´=$B0*(1-exp(-$B1*x))
end

I then give the command,

nl test y

which produces the error message:

nltest refused query, rc=198
r(196);

Under r(196) one can read, "Your nlfunc program did not work properly with 
the nl command."

What do I do wrong?

Henrik Andersson


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