Dear
I have a data.frame, and want to fit a constrained non-linear model:
data:
x
y
-0.08
20.815
-0.065
19.8128
-0.05
19.1824
-0.03
18.7346
-0.015
18.3129
0.015
18.0269
0.03
18.4715
0.05
18.9517
0.065
19.4184
0.08
20.146
0
18.2947
model:
y~exp(a)*(x-m)^4+exp(b)*(x-m)^2+const
I try to use nls() and set start=list(a=1,b=1,c=1,m=1), but which always give
me a error message that " Error in qr.solv(QR.B,cc): singular matrix 'a' in
solve". How can i build a selfStart? or any suggestion!
Thanks&Regards,
Vina
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